Co-reporter:Stephen T. Liddle and Joris van Slageren
Chemical Society Reviews 2015 vol. 44(Issue 19) pp:6655-6669
Publication Date(Web):09 Jul 2015
DOI:10.1039/C5CS00222B
Ever since the discovery that certain manganese clusters retain their magnetisation for months at low temperatures, there has been intense interest in molecular nanomagnets because of potential applications in data storage, spintronics, quantum computing, and magnetocaloric cooling. In this Tutorial Review, we summarise some key historical developments, and centre our discussion principally on the increasing trend to exploit the large magnetic moments and anisotropies of f-element ions. We focus on the important theme of strategies to improve these systems with the ultimate aim of developing materials for ultra-high-density data storage devices. We present a critical discussion of key parameters to be optimised, as well as of experimental and theoretical techniques to be used to this end.
Co-reporter:Stephen T. Liddle
Coordination Chemistry Reviews 2015 Volumes 293–294() pp:211-227
Publication Date(Web):15 June 2015
DOI:10.1016/j.ccr.2014.09.011
•Cyclobutadienyl complexes of uranium reviewed.•Absence of cyclopentadienyl complexes of uranium noted.•Arene complexes of uranium reviewed.•Cycloheptatrienyl complexes of uranium reviewed.•Cyclooctatetraenyl complexes of uranium reviewed.The chemistry of arene complexes of uranium has for over half a century been an important facet of organoactinide chemistry. Within this extensive and burgeoning field, in the past two decades inverted sandwich complexes have emerged incorporating cyclobutadienyl, arene, cycloheptatrienyl, and cyclooctatetraenyl ligands. Herein, the field is reviewed with an emphasis on well-defined molecular species that have been unambiguously characterised by X-ray crystallography.
Co-reporter:Benedict M. Gardner and Stephen T. Liddle
Chemical Communications 2015 vol. 51(Issue 53) pp:10589-10607
Publication Date(Web):02 Jun 2015
DOI:10.1039/C5CC01360G
Triamidoamine (Tren) complexes of the p- and d-block elements have been well-studied, and they display a diverse array of chemistry of academic, industrial and biological significance. Such in-depth investigations are not as widespread for Tren complexes of uranium, despite the general drive to better understand the chemical behaviour of uranium by virtue of its fundamental position within the nuclear sector. However, the chemistry of Tren–uranium complexes is characterised by the ability to stabilise otherwise reactive, multiply bonded main group donor atom ligands, construct uranium–metal bonds, promote small molecule activation, and support single molecule magnetism, all of which exploit the steric, electronic, thermodynamic and kinetic features of the Tren ligand system. This Feature Article presents a current account of the chemistry of Tren–uranium complexes.
Co-reporter:Erli Lu and Stephen T. Liddle
Dalton Transactions 2015 vol. 44(Issue 29) pp:12924-12941
Publication Date(Web):23 Jun 2015
DOI:10.1039/C5DT00608B
Oxidative addition, and its reverse reaction reductive elimination, constitute two key reactions that underpin organometallic chemistry and catalysis. Although these reactions have been known for decades in main group and transition metal systems, they are exceptionally rare or unknown for the f-block. However, in recent years much progress has been made. In this Perspective article, advances in uranium-mediated oxidative addition/reductive elimination, since the point that this research area was initiated in the early-1980s, are summarised. We principally divide the Perspective into two parts of oxidative addition and reductive elimination, along with a separate section concerning reactions where there is no change of uranium oxidation state in reactant and product but the reaction has the formal appearance of a ‘concerted’ reductive elimination/oxidative addition from the perspective of the net result. This body of work highlights that whilst uranium is capable of performing reactions that to some extent conform to traditional reactivity types, novel reactivity that has no counterpart anywhere else can be performed, thus adding to the rich palate of redox chemistry that uranium can mediate.
Co-reporter:Dipti Patel, Ashley J. Wooles, Emtithal Hashem, Harrison Omorodion, Robert J. Baker and Stephen T. Liddle
New Journal of Chemistry 2015 vol. 39(Issue 10) pp:7559-7562
Publication Date(Web):14 Apr 2015
DOI:10.1039/C5NJ00476D
We report that U3O8, UO2(NO3)2·6H2O, and UO2Cl2 react with hexachloropropene (HCP) to give UCl4 in 60, 100, and 92% yields, respectively, and report a protocol to recycle the HCP. This renders the preparation of UCl4 more accessible and sustainable. 2,5-Dichlorohexachlorofulvene has been identified as a significant by-product from these reactions.
Co-reporter: Stephen T. Liddle
Angewandte Chemie 2015 Volume 127( Issue 30) pp:8726-8764
Publication Date(Web):
DOI:10.1002/ange.201412168
Abstract
Bis zum Jahr 2000 umfasste die nichtwässrige Uranchemie hauptsächlich Metallocen- und klassische Alkyl-, Amid- oder Alkoxidverbindungen sowie bekannte Carben-, Imido- und Oxoderivate. Seither hat das Gebiet einen starken Aufschwung erfahren, einhergehend mit der Entwicklung von Hilfsliganden, mehrfach bindenden Ligandenarten, der Aktivierung niedermolekularer Verbindungen und der Untersuchung magnetischer Eigenschaften. Dieser Aufsatz führt in die theoretischen Grundlagen des Gebiets ein, behandelt wichtige Ausgangsstoffe und untersucht neuere Ligandenklassen für Uran, einschließlich Alkyle, Aryle, Arene, Carbene, Amide, Imide, Nitride, Alkoxide, Aryloxide und Oxoeinheiten. Des Weiteren werden die Fortschritte auf dem Gebiet des Einzelmolekülmagnetismus beschrieben, bevor eine Zusammenfassung der Koordination und Aktivierung niedermolekularer Verbindungen, einschließlich Kohlenmonoxid, Kohlendioxid, Stickstoffmonoxid, Distickstoff, weißem Phosphor und Alkanen, gegeben wird.
Co-reporter:Dr. Benedict M. Gardner;Dr. Floriana Tuna; Eric J. L. McInnes;Dr. Jonathan McMaster;Dr. William Lewis; Alexer J. Blake; Stephen T. Liddle
Angewandte Chemie 2015 Volume 127( Issue 24) pp:7174-7178
Publication Date(Web):
DOI:10.1002/ange.201501728
Abstract
Reaction of [U(TrenTIPS)] [1, TrenTIPS=N(CH2CH2NSiiPr3)3] with 0.25 equivalents of P4 reproducibly affords the unprecedented actinide inverted sandwich cyclo-P5 complex [{U(TrenTIPS)}2(μ-η5:η5-cyclo-P5)] (2). All prior examples of cyclo-P5 are stabilized by d-block metals, so 2 shows that cyclo-P5 does not require d-block ions to be prepared. Although cyclo-P5 is isolobal to cyclopentadienyl, which usually bonds to metals via σ- and π-interactions with minimal δ-bonding, theoretical calculations suggest the principal bonding in the U(P5)U unit is polarized δ-bonding. Surprisingly, the characterization data are overall consistent with charge transfer from uranium to the cyclo-P5 unit to give a cyclo-P5 charge state that approximates to a dianionic formulation. This is ascribed to the larger size and superior acceptor character of cyclo-P5 compared to cyclopentadienyl, the strongly reducing nature of uranium(III), and the availability of uranium δ-symmetry 5f orbitals.
Co-reporter:Dr. Benedict M. Gardner;Dr. Floriana Tuna; Eric J. L. McInnes;Dr. Jonathan McMaster;Dr. William Lewis; Alexer J. Blake; Stephen T. Liddle
Angewandte Chemie International Edition 2015 Volume 54( Issue 24) pp:7068-7072
Publication Date(Web):
DOI:10.1002/anie.201501728
Abstract
Reaction of [U(TrenTIPS)] [1, TrenTIPS=N(CH2CH2NSiiPr3)3] with 0.25 equivalents of P4 reproducibly affords the unprecedented actinide inverted sandwich cyclo-P5 complex [{U(TrenTIPS)}2(μ-η5:η5-cyclo-P5)] (2). All prior examples of cyclo-P5 are stabilized by d-block metals, so 2 shows that cyclo-P5 does not require d-block ions to be prepared. Although cyclo-P5 is isolobal to cyclopentadienyl, which usually bonds to metals via σ- and π-interactions with minimal δ-bonding, theoretical calculations suggest the principal bonding in the U(P5)U unit is polarized δ-bonding. Surprisingly, the characterization data are overall consistent with charge transfer from uranium to the cyclo-P5 unit to give a cyclo-P5 charge state that approximates to a dianionic formulation. This is ascribed to the larger size and superior acceptor character of cyclo-P5 compared to cyclopentadienyl, the strongly reducing nature of uranium(III), and the availability of uranium δ-symmetry 5f orbitals.
Co-reporter: Stephen T. Liddle
Angewandte Chemie International Edition 2015 Volume 54( Issue 30) pp:8604-8641
Publication Date(Web):
DOI:10.1002/anie.201412168
Abstract
Prior to the year 2000, non-aqueous uranium chemistry mainly involved metallocene and classical alkyl, amide, or alkoxide compounds as well as established carbene, imido, and oxo derivatives. Since then, there has been a resurgence of the area, and dramatic developments of supporting ligands and multiply bonded ligand types, small-molecule activation, and magnetism have been reported. This Review 1) introduces the reader to some of the specialist theories of the area, 2) covers all-important starting materials, 3) surveys contemporary ligand classes installed at uranium, including alkyl, aryl, arene, carbene, amide, imide, nitride, alkoxide, aryloxide, and oxo compounds, 4) describes advances in the area of single-molecule magnetism, and 5) summarizes the coordination and activation of small molecules, including carbon monoxide, carbon dioxide, nitric oxide, dinitrogen, white phosphorus, and alkanes.
Co-reporter:Benedict M. Gardner, William Lewis, Alexander J. Blake, and Stephen T. Liddle
Organometallics 2015 Volume 34(Issue 11) pp:2386-2394
Publication Date(Web):January 26, 2015
DOI:10.1021/om501177s
We report the synthesis and characterization of a range of thorium(IV)–halide, −amide, and −alkyl complexes supported by a sterically demanding triamidoamine ligand. Reaction of [ThCl4(THF)3.5] with [Li3(TrenDMBS)(THF)3] (TrenDMBS = N(CH2CH2NSiMe2But)3) gave [Th(TrenDMBS)(Cl)(THF)] (1), which was converted to [Th(TrenDMBS)(I)] (2), with concomitant elimination of Me3SiCl, by treatment with Me3SiI. Treatment of 2 with [LiNEt2] afforded [Th(TrenDMBS)(NEt2)] (3), or treatment with [PhCH2K] produced the dimeric tuck-in–tuck-over alkyl complex [Th{N(CH2CH2NSiMe2But)2(CH2CH2NSiMeBut-μ-CH2)}]2 (4), which features the longest reported Th−σ-alkyl bond distance of 2.875(9) Å. Reaction of 4 with [Et3NH][BPh4] to give the putative separated ion pair complex [Th(TrenDMBS)][BPh4] resulted in an intractable product mixture. In order to furnish a greater understanding of the latter reaction, the solvent-separated ion pair complex [U(TrenDMBS)(NCMe)2][BPh4] (5) was prepared from the monomeric uranium analogue of 4, [U{N(CH2CH2NSiMe2But)2(CH2CH2NSiMeBut-μ-CH2)}] (I), to provide a related model complex and to examine potential routes to useful TrenDMBS–actinide precursors. The nascent reactivity of 4 is suggested by the isolation of a small quantity of the oxo-insertion product [Th{N(CH2CH2NSiMe2But)2(CH2CH2NSiMeButCH2-μ-O)}]2 (6) when 4 is stored in diethyl ether. The complexes have been variously characterized by single-crystal X-ray diffraction, NMR spectroscopy, FTIR spectroscopy, Evans method solution magnetic moment determination, and CHN elemental analyses.
Co-reporter:David M. King ; Jonathan McMaster ; Floriana Tuna ; Eric J. L. McInnes ; William Lewis ; Alexander J. Blake
Journal of the American Chemical Society 2014 Volume 136(Issue 15) pp:5619-5622
Publication Date(Web):April 3, 2014
DOI:10.1021/ja502405e
Deprotonation of [U(TrenTIPS)(NH2)] (1) [TrenTIPS = N(CH2CH2NSiPri3)3] with organoalkali metal reagents MR (M = Li, R = But; M = Na–Cs, R = CH2C6H5) afforded the imido-bridged dimers [{U(TrenTIPS)(μ-N[H]M)}2] [M = Li–Cs (2a–e)]. Treatment of 2c (M = K) with 2 equiv of 15-crown-5 ether (15C5) afforded the uranium terminal parent imido complex [U(TrenTIPS)(NH)][K(15C5)2] (3c), which can also be viewed as a masked uranium(IV) nitride. The uranium–imido linkage was found to be essentially linear, and theoretical calculations suggested σ2π4 polarized U–N multiple bonding. Attempts to oxidize 3c to afford the neutral uranium terminal parent imido complex [U(TrenTIPS)(NH)] (4) resulted in spontaneous disproportionation to give 1 and the uranium–nitride complex [U(TrenTIPS)(N)] (5); this reaction is a new way to prepare the terminal uranium–nitride linkage and was calculated to be exothermic by −3.25 kcal mol–1.
Co-reporter:David M. King, Stephen T. Liddle
Coordination Chemistry Reviews 2014 Volumes 266–267() pp:2-15
Publication Date(Web):May 2014
DOI:10.1016/j.ccr.2013.06.013
•Uranium nitride matrix isolation experiments reviewed.•Aspects of uranium nitride materials chemistry and applications reviewed.•Molecular bridging uranium nitrides reviewed.•Photochemical approaches to terminal uranium nitrides reviewed.•Molecular terminal uranium nitrides reviewed.The coordination, organometallic, and materials chemistry of uranium nitride has long been an important facet of actinide chemistry. Following matrix isolation experiments and computational characterisation, molecular, solution-based uranium chemistry has developed significantly in the last decade or so culminating most recently in the isolation of the first examples of long-sought terminal uranium nitride linkages. Herein, the field is reviewed with an emphasis on well-defined molecular species.The chemistry of molecular uranium nitrides is reviewed.
Co-reporter:Benedict M. Gardner, Peter A. Cleaves, Christos E. Kefalidis, Jian Fang, Laurent Maron, William Lewis, Alexander J. Blake and Stephen T. Liddle
Chemical Science 2014 vol. 5(Issue 6) pp:2489-2497
Publication Date(Web):26 Feb 2014
DOI:10.1039/C4SC00182F
We report on the role of 5f-orbital participation in the unexpected inversion of the σ-bond metathesis reactivity trend of triamidoamine thorium(IV) and uranium(IV) alkyls. Reaction of KCH2Ph with [U(TrenTIPS)(I)] [2a, TrenTIPS = N(CH2CH2NSiPri3)33−] gave the cyclometallate [U{N(CH2CH2NSiPri3)2(CH2CH2NSiPri2C[H]MeCH2)}] (3a) with the intermediate benzyl complex not observable. In contrast, when [Th(TrenTIPS)(I)] (2b) was treated with KCH2Ph, [Th(TrenTIPS)(CH2Ph)] (4) was isolated; which is notable as Tren N-silylalkyl metal alkyls tend to spontaneously cyclometallate. Thermolysis of 4 results in the extrusion of toluene and formation of the cyclometallate [Th{N(CH2CH2NSiPri3)2(CH2CH2NSiPri2C[H]MeCH2)}] (3b). This reactivity is the reverse of what would be predicted. Since the bonding of thorium is mainly electrostatic it would be predicted to undergo facile cyclometallation, whereas the more covalent uranium system might be expected to form an isolable benzyl intermediate. The thermolysis of 4 follows well-defined first order kinetics with an activation energy of 22.3 ± 0.1 kcal mol−1, and Eyring analyses yields ΔH‡ = 21.7 ± 3.6 kcal mol−1 and ΔS‡ = −10.5 ± 3.1 cal K−1 mol−1, which is consistent with a σ-bond metathesis reaction. Computational examination of the reaction profile shows that the inversion of the reactivity trend can be attributed to the greater f-orbital participation of the bonding for uranium facilitating the σ-bond metathesis transition state whereas for thorium the transition state is more ionic resulting in an isolable benzyl complex. The activation barriers are computed to be 19.0 and 22.2 kcal mol−1 for the uranium and thorium cases, respectively, and the latter agrees excellently with the experimental value. Reductive decomposition of “[U(TrenTIPS)(CH2Ph)]” to [U(TrenTIPS)] and bibenzyl followed by cyclometallation to give 3a with elimination of dihydrogen was found to be endergonic by 4 kcal mol−1 which rules out a redox-based cyclometallation route for uranium.
Co-reporter:Oliver J. Cooper, David P. Mills, William Lewis, Alexander J. Blake and Stephen T. Liddle
Dalton Transactions 2014 vol. 43(Issue 38) pp:14275-14283
Publication Date(Web):25 Apr 2014
DOI:10.1039/C4DT00909F
The reactivity of the uranium(IV) carbene complex [U(BIPMTMS)(Cl)(μ-Cl)2Li(THF)2] (1, BIPMTMS = {C(PPh2NSiMe3)2}) towards carbonyl and heteroallene substrates is reported. Reaction of 1 with benzophenone proceeds to give the metallo-Wittig terminal alkene product Ph2CC(PPh2NSiMe3)2 (2); the likely “UOCl2” byproduct could not be isolated. Addition of the bulky ketone PhCOBut to 1 resulted in loss of LiCl, coordination of the ketone, and dimerisation to give [U(BIPMTMS)(Cl)(μ-Cl){OC(Ph)(But)}]2 (3). The reaction of 1 with coumarin resulted in ring opening of the cyclic ester and a metallo-Wittig-type reaction to afford [U{BIPMTMS[C(O)(CHCHC6H4O-2)]-κ3-N,O,O′}(Cl)2(THF)] (4) where the enolate product remains coordinated to uranium. The reaction of PhCOF with 1 resulted in C–F bond activation and oxidation resulting in isolation of [U(O)2(Cl)2(μ-Cl)2{(μ-LiDME)OC(Ph)C(PPh2NSiMe3)(PPh2NHSiMe3)}2] (5) along with [U(Cl)2(F)2(py)4] (6). The reactions of 1 with tert-butylisocyanate or dicyclohexylcarbodiimide resulted in the isolation of the [2 + 2]-cycloaddition products [U{BIPMTMS[C(NBut){OLi(THF)2(μ-Cl)Li(THF)3}]-κ4-C,N,N′,N′′}(Cl)3] (7) and [U{BIPMTMS[C(NCy)2]-κ4-C,N,N′,N′′}(Cl)(μ-Cl)2Li(THF)2] (8). Complexes 2–8 have been variously characterised by single crystal X-ray diffraction, multi-nuclear NMR and FTIR spectroscopies, Evans method solution magnetic moments, variable temperature SQUID magnetometry, and elemental analyses.
Co-reporter:Sarah Robinson, E. Stephen Davies, William Lewis, Alexander J. Blake and Stephen T. Liddle
Dalton Transactions 2014 vol. 43(Issue 11) pp:4351-4360
Publication Date(Web):31 Oct 2013
DOI:10.1039/C3DT52632A
Treatment of the ortho-phenylene diamine C6H4-1,2-{N(H)Tripp}2 (1, PDAH2, Tripp = 2,4,6-triisopropylphenyl) with two equivalents of MR (M = Li, R = Bun; M = Na or K, R = CH2C6H5) afforded the dimetallated alkali metal ortho-phenylene diamide dianion complexes [(PDALi2)(THF)3] (2), [{(PDANa2)(THF)2}2] (3), and [{(PDAK2)(THF)3}2] (4). In contrast, treatment of 2 with two equivalents of rubidium or cesium 2-ethylhexoxide, or treatment of 1 with two equivalents of MR (M = Rb or Cs, R = CH2C6H5) did not afford the anticipated dialkali metal ortho-phenylene diamide dianion derivatives and instead formally afforded the monometallic ortho-diiminosemiquinonate radical anion species [PDAM] (M = Rb, 5; M = Cs, 6). The structure of 2 is monomeric with one lithium coordinated to the two nitrogen centres and the other lithium η4-coordinated to the diazabutadiene portion of the PDA scaffold. Similar structural cores are observed for 3 and 4, except that the larger sodium and potassium ions give dimeric structures linked by multi-hapto interactions from the PDA backbone phenyl ring to an alkali metal centre. Complex 5 was not characterised in the solid state, but the structure of 6 reveals coordination of cesium ions to both PDA amide centres and multi-hapto interactions to a PDA backbone phenyl ring in the next unit to generate a one-dimensional polymer. Complexes 2–6 have been variously characterised by X-ray crystallography, multi-nuclear NMR, FTIR, and EPR spectroscopies, and CHN microanalyses.
Co-reporter:Dr. Erli Lu;Dr. Oliver J. Cooper;Dr. Jonathan McMaster;Dr. Floriana Tuna; Eric J. L. McInnes;Dr. William Lewis; Alexer J. Blake; Stephen T. Liddle
Angewandte Chemie 2014 Volume 126( Issue 26) pp:6814-6818
Publication Date(Web):
DOI:10.1002/ange.201403892
Abstract
We report the uranium(VI) carbene imido oxo complex [U(BIPMTMS)(NMes)(O)(DMAP)2] (5, BIPMTMS=C(PPh2NSiMe3)2; Mes=2,4,6-Me3C6H2; DMAP=4-(dimethylamino)pyridine) which exhibits the unprecedented arrangement of three formal multiply bonded ligands to one metal center where the coordinated heteroatoms derive from different element groups. This complex was prepared by incorporation of carbene, imido, and then oxo groups at the uranium center by salt elimination, protonolysis, and two-electron oxidation, respectively. The oxo and imido groups adopt axial positions in a T-shaped motif with respect to the carbene, which is consistent with an inverse trans-influence. Complex 5 reacts with tert-butylisocyanate at the imido rather than carbene group to afford the uranyl(VI) carbene complex [U(BIPMTMS)(O)2(DMAP)2] (6).
Co-reporter:Dr. Erli Lu;Dr. Oliver J. Cooper;Dr. Jonathan McMaster;Dr. Floriana Tuna; Eric J. L. McInnes;Dr. William Lewis; Alexer J. Blake; Stephen T. Liddle
Angewandte Chemie International Edition 2014 Volume 53( Issue 26) pp:6696-6700
Publication Date(Web):
DOI:10.1002/anie.201403892
Abstract
We report the uranium(VI) carbene imido oxo complex [U(BIPMTMS)(NMes)(O)(DMAP)2] (5, BIPMTMS=C(PPh2NSiMe3)2; Mes=2,4,6-Me3C6H2; DMAP=4-(dimethylamino)pyridine) which exhibits the unprecedented arrangement of three formal multiply bonded ligands to one metal center where the coordinated heteroatoms derive from different element groups. This complex was prepared by incorporation of carbene, imido, and then oxo groups at the uranium center by salt elimination, protonolysis, and two-electron oxidation, respectively. The oxo and imido groups adopt axial positions in a T-shaped motif with respect to the carbene, which is consistent with an inverse trans-influence. Complex 5 reacts with tert-butylisocyanate at the imido rather than carbene group to afford the uranyl(VI) carbene complex [U(BIPMTMS)(O)2(DMAP)2] (6).
Co-reporter:Dr. Erli Lu;Dr. William Lewis; Alexer J. Blake ; Stephen T. Liddle
Angewandte Chemie 2014 Volume 126( Issue 35) pp:9510-9513
Publication Date(Web):
DOI:10.1002/ange.201404898
Abstract
The ketimide anion R2CN− is an important class of chemically robust ligand that binds strongly to metal ions and is considered ideal for supporting reactive metal fragments due to its inert spectator nature; this contrasts with R2N− amides that exhibit a wide range of reactivities. Here, we report the synthesis and characterization of a rare example of an actinide ketimide complex [Th(BIPMTMS){N(SiMe3)2}(NCPh2)] [2, BIPMTMS=C(PPh2NSiMe3)2]. Complex 2 contains ThCcarbene, ThNamide and ThNketimide linkages, thereby presenting the opportunity to probe the preferential reactivity of these linkages. Importantly, reactivity studies of 2 with unsaturated substrates shows that insertion reactions occur preferentially at the ThNketimide bond rather than at the ThCcarbene or ThNamide bonds. This overturns the established view that metal-ketimide linkages are purely inert spectators.
Co-reporter:Dr. Benedict M. Gardner;Dr. Gábor Balázs;Dr. Manfred Scheer;Dr. Floriana Tuna; Eric J. L. McInnes;Dr. Jonathan McMaster;Dr. William Lewis; Alexer J. Blake; Stephen T. Liddle
Angewandte Chemie International Edition 2014 Volume 53( Issue 17) pp:4484-4488
Publication Date(Web):
DOI:10.1002/anie.201400798
Abstract
Reaction of [U(TrenTIPS)(THF)][BPh4] (1; TrenTIPS=N{CH2CH2NSi(iPr)3}3) with NaPH2 afforded the novel f-block terminal parent phosphide complex [U(TrenTIPS)(PH2)] (2; U–P=2.883(2) Å). Treatment of 2 with one equivalent of KCH2C6H5 and two equivalents of benzo-15-crown-5 ether (B15C5) afforded the unprecedented metal-stabilized terminal parent phosphinidene complex [U(TrenTIPS)(PH)][K(B15C5)2] (4; UP=2.613(2) Å). DFT calculations reveal a polarized-covalent UP bond with a Mayer bond order of 1.92.
Co-reporter:Dr. Erli Lu;Dr. William Lewis; Alexer J. Blake ; Stephen T. Liddle
Angewandte Chemie International Edition 2014 Volume 53( Issue 35) pp:9356-9359
Publication Date(Web):
DOI:10.1002/anie.201404898
Abstract
The ketimide anion R2CN− is an important class of chemically robust ligand that binds strongly to metal ions and is considered ideal for supporting reactive metal fragments due to its inert spectator nature; this contrasts with R2N− amides that exhibit a wide range of reactivities. Here, we report the synthesis and characterization of a rare example of an actinide ketimide complex [Th(BIPMTMS){N(SiMe3)2}(NCPh2)] [2, BIPMTMS=C(PPh2NSiMe3)2]. Complex 2 contains ThCcarbene, ThNamide and ThNketimide linkages, thereby presenting the opportunity to probe the preferential reactivity of these linkages. Importantly, reactivity studies of 2 with unsaturated substrates shows that insertion reactions occur preferentially at the ThNketimide bond rather than at the ThCcarbene or ThNamide bonds. This overturns the established view that metal-ketimide linkages are purely inert spectators.
Co-reporter:Peter A. Cleaves;Dr. David M. King;Dr. Christos E. Kefalidis; Laurent Maron;Dr. Floriana Tuna; Eric J. L. McInnes;Dr. Jonathan McMaster;Dr. William Lewis; Alexer J. Blake; Stephen T. Liddle
Angewandte Chemie International Edition 2014 Volume 53( Issue 39) pp:10412-10415
Publication Date(Web):
DOI:10.1002/anie.201406203
Abstract
Two-electron reductive carbonylation of the uranium(VI) nitride [U(TrenTIPS)(N)] (2, TrenTIPS=N(CH2CH2NSiiPr3)3) with CO gave the uranium(IV) cyanate [U(TrenTIPS)(NCO)] (3). KC8 reduction of 3 resulted in cyanate dissociation to give [U(TrenTIPS)] (4) and KNCO, or cyanate retention in [U(TrenTIPS)(NCO)][K(B15C5)2] (5, B15C5=benzo-15-crown-5 ether) with B15C5. Complexes 5 and 4 and KNCO were also prepared from CO and the uranium(V) nitride [{U(TrenTIPS)(N)K}2] (6), with or without B15C5, respectively. Complex 5 can be prepared directly from CO and [U(TrenTIPS)(N)][K(B15C5)2] (7). Notably, 7 reacts with CO much faster than 2. This unprecedented f-block reactivity was modeled theoretically, revealing nucleophilic attack of the π* orbital of CO by the nitride with activation energy barriers of 24.7 and 11.3 kcal mol−1 for uranium(VI) and uranium(V), respectively. A remarkably simple two-step, two-electron cycle for the conversion of azide to nitride to cyanate using 4, NaN3 and CO is presented.
Co-reporter:Dipti Patel, Floriana Tuna, Eric J. L. McInnes, Jonathan McMaster, William Lewis, Alexander J. Blake and Stephen T. Liddle
Dalton Transactions 2013 vol. 42(Issue 15) pp:5224-5227
Publication Date(Web):20 Feb 2013
DOI:10.1039/C3DT50255D
Reduction of [U(TsTol)(Cl)(μ-Cl)U(TsTol)(THF)2] [2, TsTol = HC(SiMe2NAr′)3; Ar′ = 4-MeC6H4)] with KC8 in toluene afforded the new arene-bridged diuranium complex [{U(TsTol)}2(μ–η6:η6-C6H5Me)] (3); combined structural, spectroscopic, magnetic, and computational analyses unambiguously confirm that the uranium centres in 3 are in the +5 oxidation state and the toluene is a 10π-tetraanion.
Co-reporter:Benedict M. Gardner
European Journal of Inorganic Chemistry 2013 Volume 2013( Issue 22-23) pp:3753-3770
Publication Date(Web):
DOI:10.1002/ejic.201300111
Abstract
Over the last 15 years or so, it has been shown that low-valent, electron-rich uranium(III) complexes exhibit a wide variety of reactivity towards small molecules. As a result, the field of uranium-mediated small-molecule activation chemistry has undergone significant development in recent years. The classical organometallic reactivity patterns of oxidative addition and reductive elimination that dominate the chemistry of transition-metal complexes are much less common for uranium. Owing to the invocation of the 5f orbitals for bonding and the highly polarising nature of the actinide centre, the prevalent reactivity observed for non-aqueous uranium compounds is that of migratory insertion, σ-bond metathesis and redox activity, and this can account for the often unexpected chemistry encountered with these species. This microreview focuses on the activation chemistry of trivalent uranium complexes towards the important small molecules dinitrogen (N2), nitric oxide (NO), azide (N3–), carbon monoxide (CO) and carbon dioxide (CO2).
Co-reporter:David P. Mills, William Lewis, Alexander J. Blake, and Stephen T. Liddle
Organometallics 2013 Volume 32(Issue 5) pp:1239-1250
Publication Date(Web):February 12, 2013
DOI:10.1021/om301016j
The yttrium carbene complex [Y(BIPM)(I)(THF)2] (1; BIPM = C(PPh2NSiMe3)2) was reacted with a range of unsaturated substrates. The reaction of 1 with the phosphaalkyne PCBut afforded the [2 + 2] cycloaddition product [Y{C(PPh2NSiMe3)2(PCBut)-κ4C,C′,N,N′}(I)] (2). Similarly, the reactions of 1 with the heteroallenes N,N′-dicyclohexylcarbodiimide and tert-butyl isocyanate gave the [2 + 2] cycloaddition products [Y{C(PPh2NSiMe3)2[C(NCy)2]-κ4C,N,N′,N″}(I)(THF)] (3) and [Y{C(PPh2NSiMe3)2[C(O)(NBut)]-κ4C,N,N′,O}(I)(THF)2] (4), respectively. In contrast, the reaction of 1 with tert-butyl isothiocyanate afforded the ketenimine ButN═C═C(PPh2NSiMe3)2 (5), with the concomitant formal elimination of “YSI(THF)n”. The sterically demanding arylamine 2,6-diisopropylphenylamine reacted with 1 via a 1,2-addition across the Y═C bond to yield the anilide–methanide complex [Y(BIPMH)(NHDipp)(I)(THF)] (6; Dipp = C6H3Pri2-2,6). The reaction of 1 with the benzopyrone coumarin affords the ring-opened dinuclear aryloxide–enolate complex [Y2{C(PPh2NSiMe3)2[C(O)(CHCHC6H4O-2)]-κ2-N,O:μ,κ-O′}2(I)(μ-I)(THF)] (7), which is postulated to form by sequential Y–O, C–C, and C═C bond formation and cleavage of the C–O ester linkage and the C═O and Y═C double bonds. Benzoyl fluoride reacts with 1 to afford 1/2 equiv of the bis-enolate complex [Y{C(PPh2NSiMe3)2[C(O)(Ph)]-κ2N,O}2(I)] (8) with formal elimination of “YF2I(THF)n” by ligand scrambling. Complexes 2–8 have been characterized by X-ray crystallography, multielement NMR spectroscopy, FTIR spectroscopy, and CHN microanalyses.
Co-reporter:Dr. Dipti Patel;Dr. Floriana Tuna; Eric J. L. McInnes;Dr. William Lewis; Alexer J. Blake; Stephen T. Liddle
Angewandte Chemie International Edition 2013 Volume 52( Issue 50) pp:13334-13337
Publication Date(Web):
DOI:10.1002/anie.201306492
Co-reporter:Matthew Gregson;Dr. Erli Lu;Dr. Jonathan McMaster;Dr. William Lewis; Alexer J. Blake ; Stephen T. Liddle
Angewandte Chemie International Edition 2013 Volume 52( Issue 49) pp:13016-13019
Publication Date(Web):
DOI:10.1002/anie.201306984
Co-reporter:Oliver J. Cooper;Dr. David P. Mills;Dr. Jonathan McMaster;Dr. Floriana Tuna; Eric. J. L. McInnes;Dr. William Lewis; Alexer J. Blake;Dr. Stephen T. Liddle
Chemistry - A European Journal 2013 Volume 19( Issue 22) pp:7071-7083
Publication Date(Web):
DOI:10.1002/chem.201300071
Abstract
Treatment of [K(BIPMMesH)] (BIPMMes={C(PPh2NMes)2}2−; Mes=C6H2-2,4,6-Me3) with [UCl4(thf)3] (1 equiv) afforded [U(BIPMMesH)(Cl)3(thf)] (1), which generated [U(BIPMMes)(Cl)2(thf)2] (2), following treatment with benzyl potassium. Attempts to oxidise 2 resulted in intractable mixtures, ligand scrambling to give [U(BIPMMes)2] or the formation of [U(BIPMMesH)(O)2(Cl)(thf)] (3). The complex [U(BIPMDipp)(μ-Cl)4(Li)2(OEt2)(tmeda)] (4) (BIPMDipp={C(PPh2NDipp)2}2−; Dipp=C6H3-2,6-iPr2; tmeda=N,N,N′,N′-tetramethylethylenediamine) was prepared from [Li2(BIPMDipp)(tmeda)] and [UCl4(thf)3] and, following reflux in toluene, could be isolated as [U(BIPMDipp)(Cl)2(thf)2] (5). Treatment of 4 with iodine (0.5 equiv) afforded [U(BIPMDipp)(Cl)2(μ-Cl)2(Li)(thf)2] (6). Complex 6 resists oxidation, and treating 4 or 5 with N-oxides gives [{U(BIPMDippH)(O)2- (μ-Cl)2Li(tmeda)] (7) and [{U(BIPMDippH)(O)2(μ-Cl)}2] (8). Treatment of 4 with tBuOLi (3 equiv) and I2 (1 equiv) gives [U(BIPMDipp)(OtBu)3(I)] (9), which represents an exceptionally rare example of a crystallographically authenticated uranium(VI)–carbon σ bond. Although 9 appears sterically saturated, it decomposes over time to give [U(BIPMDipp)(OtBu)3]. Complex 4 reacts with PhCOtBu and Ph2CO to form [U(BIPMDipp)(μ-Cl)4(Li)2(tmeda)(OCPhtBu)] (10) and [U(BIPMDipp)(Cl)(μ-Cl)2(Li)(tmeda)(OCPh2)] (11). In contrast, complex 5 does not react with PhCOtBu and Ph2CO, which we attribute to steric blocking. However, complexes 5 and 6 react with PhCHO to afford (DippNPPh2)2CC(H)Ph (12). Complex 9 does not react with PhCOtBu, Ph2CO or PhCHO; this is attributed to steric blocking. Theoretical calculations have enabled a qualitative bracketing of the extent of covalency in early-metal carbenes as a function of metal, oxidation state and the number of phosphanyl substituents, revealing modest covalent contributions to UC double bonds.
Co-reporter:Ashley J. Wooles, William Lewis, Alexander J. Blake, and Stephen T. Liddle
Organometallics 2013 Volume 32(Issue 18) pp:5058-5070
Publication Date(Web):September 6, 2013
DOI:10.1021/om400435b
Treatment of [M(Bn)] (M = K, Cs) with [HC{C(But)NDipp}{C(But)NHDipp}] (LButH; Dipp = 2,6-diisopropylphenyl) afforded [K(LBut)(THF)n], 1, and [Cs(LBut)], 2, which were crystallized from hexane or benzene to afford [K(LBut)(THF)3], 1a, and [{Cs(LBut)}{Cs(LBut)(η3-C6D6)}·C6D6]∞, 2a, respectively. Complexes 1 and 2 were utilized in the preparation of the previously reported [U(LBut)Cl3], which was cleanly converted to [U(LBut)I3], 3, via reaction with an excess of Me3SiI. Attempts to prepare U(III) complexes incorporating the LBut ligand proved unsuccessful, but utilizing [HC{C(Me)NDipp}{C(Me)NHDipp}] (LMeH) led to the isolation of [U(LMe)I2(THF)2], 4, via the reaction of [K(LMe)] with [U(I)3(THF)4]. Complex 4 can be derivatized via reaction with [K(Cp*)] (Cp* = η5-C5Me5) or [K{N(SiMe3)2}] to afford [U(LMe)(Cp*)I], 5, and [U(LMe){N(SiMe3)2}I], 6, respectively. The reaction of 4 with two equivalents of [K{N(SiMe3)2}] did not afford [U(LMe){N(SiMe3)2}2] as expected, but instead led to the isolation of the U(IV) species [U{HC[C(Me)NDipp][C(CH2)NDipp]}{N(SiMe3)2}2], 7, via deprotonation of the LMe ligand. The reduction of 4 with KC8 in benzene afforded the diuranium inverse sandwich complex [{U(LMe)I}2(μ-η6:η6-C6H6)], 8, albeit in low yield. Complexes 1–8 have been characterized by single-crystal X-ray diffraction studies, by multielement NMR spectroscopy, and variously by FTIR spectroscopy, elemental analysis, UV/vis/NIR spectroscopy, and solution-state magnetic studies.
Co-reporter:David P. Mills, Lyndsay Soutar, Oliver J. Cooper, William Lewis, Alexander J. Blake, and Stephen T. Liddle
Organometallics 2013 Volume 32(Issue 5) pp:1251-1264
Publication Date(Web):December 18, 2012
DOI:10.1021/om3010178
The yttrium alkyl carbene complex [Y(BIPM)(CH2Ph)(THF)] (1; BIPM = {C(PPh2NSiMe3)2})2–) was treated with a series of unsaturated organic substrates, a bulky primary amine, and a group 1 metal alkyl to gauge and compare the reactivity of the Y═Ccarbene and Y–Calkyl bonds. Treatment of 1 with tert-butyl nitrile and 1-adamantyl azide gave the 1,2-migratory insertion products [Y(BIPM){NC(But)(CH2Ph)}(THF)] (2) and [Y(BIPM){N3Ad-1,Bn-3-κ2N1,3}(THF)] (3), respectively, with no reactivity observed at the Y═C double bond even when an excess of the relevant organic substrate was added. In contrast, the heteroallenes N,N′-dicyclohexylcarbodiimide and tert-butyl isocyanate reacted at both the Y═Ccarbeneand Y–Calkyl bonds of 1 to afford [Y{C(PPh2NSiMe3)2[C(NCy)2]-κ4C,N,N′,N″}{C(NCy)2(CH2Ph)-κ2N,N′}] (4) and [Y{C(PPh2NSiMe3)2[C(O)(NBut)]-κ4C,N,N′,O}{C(O)(NBut)(CH2Ph)-κ2N,O}] (5), respectively. 4 and 5 form regardless of the molar ratio of 1 to heteroallene, with no intermediates observed; thus, it is not clear if the [2 + 2]-cycloaddition or the 1,2-migratory insertion reaction occurs first. The addition of 2 equiv of tert-butyl isothiocyanate to 1 yields dimeric [Y(BIPMH){C(S)2(NBut)-1-κS,2-κN:μ,κS′}]2 (6), benzyl nitrile, and isobutylene by desulfurization and carbene-mediated deprotonation of a tert-butyl group of 1 equiv of heteroallene. The reaction between 1 and the bulky amine DippNH2 (Dipp = C6H3Pri2) gave [Y(BIPM)(NHDipp)(THF)] (7) by alkane elimination, with no reactivity observed at the Y═Ccarbene bond. Finally, the addition of benzylpotassium to 1 afforded the yttriate polymer [Y(BIPM)(μ-η1:η6-CH2Ph)(μ-η1:η2-CH2Ph)K]∞ (8) by a formal carbopotassiation across the Y═Ccarbene bond. Complexes 2–8 have been characterized by X-ray crystallography, multielement NMR spectroscopy, FTIR spectroscopy, and CHN microanalyses.
Co-reporter:Matthew Gregson;Dr. Erli Lu;Dr. Jonathan McMaster;Dr. William Lewis; Alexer J. Blake ; Stephen T. Liddle
Angewandte Chemie 2013 Volume 125( Issue 49) pp:13254-13257
Publication Date(Web):
DOI:10.1002/ange.201306984
Co-reporter:Dr. Dipti Patel;Dr. Floriana Tuna; Eric J. L. McInnes;Dr. William Lewis; Alexer J. Blake; Stephen T. Liddle
Angewandte Chemie 2013 Volume 125( Issue 50) pp:13576-13579
Publication Date(Web):
DOI:10.1002/ange.201306492
Co-reporter:David M. King;Dr. Floriana Tuna;Dr. Jonathan McMaster;Dr. William Lewis; Alexer J. Blake; Eric J. L. McInnes;Dr. Stephen T. Liddle
Angewandte Chemie International Edition 2013 Volume 52( Issue 18) pp:4921-4924
Publication Date(Web):
DOI:10.1002/anie.201301007
Co-reporter:Dr. Fabrizio Moro;Dr. David P. Mills;Dr. Stephen T. Liddle;Dr. Joris vanSlageren
Angewandte Chemie International Edition 2013 Volume 52( Issue 12) pp:3430-3433
Publication Date(Web):
DOI:10.1002/anie.201208015
Co-reporter:Dr. Fabrizio Moro;Dr. David P. Mills;Dr. Stephen T. Liddle;Dr. Joris vanSlageren
Angewandte Chemie 2013 Volume 125( Issue 12) pp:3514-3517
Publication Date(Web):
DOI:10.1002/ange.201208015
Co-reporter:David P. Mills ; Oliver J. Cooper ; Floriana Tuna ; Eric J. L. McInnes ; E. Stephen Davies ; Jonathan McMaster ; Fabrizio Moro ; William Lewis ; Alexander J. Blake
Journal of the American Chemical Society 2012 Volume 134(Issue 24) pp:10047-10054
Publication Date(Web):May 23, 2012
DOI:10.1021/ja301333f
We report attempts to prepare uranyl(VI)- and uranium(VI) carbenes utilizing deprotonation and oxidation strategies. Treatment of the uranyl(VI)-methanide complex [(BIPMH)UO2Cl(THF)] [1, BIPMH = HC(PPh2NSiMe3)2] with benzyl-sodium did not afford a uranyl(VI)-carbene via deprotonation. Instead, one-electron reduction and isolation of di- and trinuclear [UO2(BIPMH)(μ-Cl)UO(μ-O){BIPMH}] (2) and [UO(μ-O)(BIPMH)(μ3-Cl){UO(μ-O)(BIPMH)}2] (3), respectively, with concomitant elimination of dibenzyl, was observed. Complexes 2 and 3 represent the first examples of organometallic uranyl(V), and 3 is notable for exhibiting rare cation–cation interactions between uranyl(VI) and uranyl(V) groups. In contrast, two-electron oxidation of the uranium(IV)-carbene [(BIPM)UCl3Li(THF)2] (4) by 4-morpholine N-oxide afforded the first uranium(VI)-carbene [(BIPM)UOCl2] (6). Complex 6 exhibits a trans-CUO linkage that represents a [R2C═U═O]2+ analogue of the uranyl ion. Notably, treatment of 4 with other oxidants such as Me3NO, C5H5NO, and TEMPO afforded 1 as the only isolable product. Computational studies of 4, the uranium(V)-carbene [(BIPM)UCl2I] (5), and 6 reveal polarized covalent U═C double bonds in each case whose nature is significantly affected by the oxidation state of uranium. Natural Bond Order analyses indicate that upon oxidation from uranium(IV) to (V) to (VI) the uranium contribution to the U═C σ-bond can increase from ca. 18 to 32% and within this component the orbital composition is dominated by 5f character. For the corresponding U═C π-components, the uranium contribution increases from ca. 18 to 26% but then decreases to ca. 24% and is again dominated by 5f contributions. The calculations suggest that as a function of increasing oxidation state of uranium the radial contraction of the valence 5f and 6d orbitals of uranium may outweigh the increased polarizing power of uranium in 6 compared to 5.
Co-reporter:Sarah Robinson, Jonathan McMaster, William Lewis, Alexander J. Blake and Stephen T. Liddle
Chemical Communications 2012 vol. 48(Issue 46) pp:5769-5771
Publication Date(Web):30 Apr 2012
DOI:10.1039/C2CC31758C
Reaction of lithium with PDABBr [PDA = C6H4-1,2-(NTripp)2, Tripp = 2,4,6-Pri3C6H2] and naphthalene afforded 2- and 2,6-borylated naphthalenes; conversely, use of high-sodium lithium (0.5% Na) afforded the lithium boryl [(PDAB)Li(THF)2]; this work establishes that main group reagents can achieve selective borylations of fused polycyclic aromatics under mild conditions in good yields.
Co-reporter:Benedict M. Gardner;John C. Stewart;Adrienne L. Davis;Jonathan McMaster;William Lewis;Alexander J. Blake
PNAS 2012 Volume 109 (Issue 24 ) pp:
Publication Date(Web):2012-06-12
DOI:10.1073/pnas.1203417109
Carbon monoxide (CO) is in principle an excellent resource from which to produce industrial hydrocarbon feedstocks as alternatives
to crude oil; however, CO has proven remarkably resistant to selective homologation, and the few complexes that can effect
this transformation cannot be recycled because liberation of the homologated product destroys the complexes or they are substitutionally
inert. Here, we show that under mild conditions a simple triamidoamine uranium(III) complex can reductively homologate CO
and be recycled for reuse. Following treatment with organosilyl halides, bis(organosiloxy)acetylenes, which readily convert
to furanones, are produced, and this was confirmed by the use of isotopically 13C-labeled CO. The precursor to the triamido uranium(III) complex is formed concomitantly. These findings establish that, under
appropriate conditions, uranium(III) can mediate a complete synthetic cycle for the homologation of CO to higher derivatives.
This work may prove useful in spurring wider efforts in CO homologation, and the simplicity of this system suggests that catalytic
CO functionalization may soon be within reach.
Co-reporter:David M. King;Floriana Tuna;Jonathan McMaster;William Lewis;Eric J. L. McInnes;Alexander J. Blake
Science 2012 Volume 337(Issue 6095) pp:717-720
Publication Date(Web):10 Aug 2012
DOI:10.1126/science.1223488
UN Coordination
Uranium is best known for its radioactivity. From the standpoint of lower-energy chemistry, uranium is also intriguing for its bonding motifs, which involve trinodal f orbitals. King et al. (p. 717, published online 28 June; see the Perspective by Sattelberger and Johnson) synthesized and isolated a molecule bearing a uranium-nitrogen triple bond. Theoretical calculations allowed the mapping of the orbital interactions, distinguishing it from similar motifs in compounds of lighter metals. The preparation required use of a rigid, bulky ligand framework to keep the reactive uranium nitride group from binding to another molecule nearby, a pathway that has plagued prior attempts to prepare this class of compounds.
Co-reporter:Stephen T. Liddle, David P. Mills and Ashley J. Wooles
Chemical Society Reviews 2011 vol. 40(Issue 5) pp:2164-2176
Publication Date(Web):14 Feb 2011
DOI:10.1039/C0CS00135J
Since the discovery of covalently-bound mid- and late-transition metal carbenes there has been a spectacular explosion of interest in their chemistry, but their early metal counterparts have lagged behind. In recent years, bis(phosphorus-stabilised)carbenes have emerged as valuable ligands for metals across the periodic table, and their use has in particular greatly expanded covalently-bound early metal carbene chemistry. In this tutorial review we introduce the reader to bis(phosphorus-stabilised)carbenes, and cover general preparative methods, structure and bonding features, and emerging reactivity studies of early metal derivatives (groups 1–4 and the f-elements).
Co-reporter:Dipti Patel, David M. King, Benedict M. Gardner, Jonathan McMaster, William Lewis, Alexander J. Blake and Stephen T. Liddle
Chemical Communications 2011 vol. 47(Issue 1) pp:295-297
Publication Date(Web):05 Aug 2010
DOI:10.1039/C0CC01387K
Amine-elimination gave the two uranium–rhenium complexes [(TsXy)(THF)nURe(η5-C5H5)2] [TsXy = HC(SiMe2N-3,5-Me2C6H3)3; n = 0 or 1]; structural and theoretical analyses, and comparison to [(TrenTMS)URe(η5-C5H5)2] [TrenTMS = N(CH2CH2NSiMe3)3], reveal an increasing σ-component to the U–Re bond upon removal of dative ancillary ligands from uranium with the π-component remaining essentially invariant.
Co-reporter:Benedict M. Gardner, William Lewis, Alexander J. Blake, and Stephen T. Liddle
Inorganic Chemistry 2011 Volume 50(Issue 19) pp:9631-9641
Publication Date(Web):August 31, 2011
DOI:10.1021/ic201372a
Treatment of the complex [U(TrenTMS)(Cl)(THF)] [1, TrenTMS = N(CH2CH2NSiMe3)3] with Me3SiI at room temperature afforded known crystalline [U(TrenTMS)(I)(THF)] (2), which is reported as a new polymorph. Sublimation of 2 at 160 °C and 10–6 mmHg afforded the solvent-free dimer complex [{U(TrenTMS)(μ-I)}2] (3), which crystallizes in two polymorphic forms. During routine preparations of 1, an additional complex identified as [U(Cl)5(THF)][Li(THF)4] (4) was isolated in very low yield due to the presence of a slight excess of [U(Cl)4(THF)3] in one batch. Reaction of 1 with one equivalent of lithium dicyclohexylamide or bis(trimethylsilyl)amide gave the corresponding amide complexes [U(TrenTMS)(NR2)] (5, R = cyclohexyl; 6, R = trimethylsilyl), which both afforded the cationic, separated ion pair complex [U(TrenTMS)(THF)2][BPh4] (7) following treatment of the respective amides with Et3NH·BPh4. The analogous reaction of 5 with Et3NH·BArf4 [Arf = C6H3-3,5-(CF3)2] afforded, following addition of 1 to give a crystallizable compound, the cationic, separated ion pair complex [{U(TrenTMS)(THF)}2(μ-Cl)][BArf4] (8). Reaction of 7 with K[Mn(CO)5] or 5 or 6 with [HMn(CO)5] in THF afforded [U(TrenTMS)(THF)(μ-OC)Mn(CO)4] (9); when these reactions were repeated in the presence of 1,2-dimethoxyethane (DME), the separated ion pair [U(TrenTMS)(DME)][Mn(CO)5] (10) was isolated instead. Reaction of 5 with [HMn(CO)5] in toluene afforded [{U(TrenTMS)(μ-OC)2Mn(CO)3}2] (11). Similarly, reaction of the cyclometalated complex [U{N(CH2CH2NSiMe2But)2(CH2CH2NSiMeButCH2)}] with [HMn(CO)5] gave [{U(TrenDMSB)(μ-OC)2Mn(CO)3}2] [12, TrenDMSB = N(CH2CH2NSiMe2But)3]. Attempts to prepare the manganocene derivative [U(TrenTMS)MnCp2] from 7 and K[MnCp2] were unsuccessful and resulted in formation of [{U(TrenTMS)}2(μ-O)] (13) and [MnCp2]. Complexes 3–13 have been characterized by X-ray crystallography, 1H NMR spectroscopy, FTIR spectroscopy, Evans method magnetic moment, and CHN microanalyses.
Co-reporter:Benedict M. Gardner;Dr. Jonathan McMaster;Fabrizio Moro;Dr. William Lewis; Alexer J. Blake ;Dr. Stephen T. Liddle
Chemistry - A European Journal 2011 Volume 17( Issue 25) pp:6909-6912
Publication Date(Web):
DOI:10.1002/chem.201100682
Co-reporter:Benedict M. Gardner;Dr. Dipti Patel;Andrew D. Cornish;Dr. Jonathan McMaster;Dr. William Lewis; Alexer J. Blake ;Dr. Stephen T. Liddle
Chemistry - A European Journal 2011 Volume 17( Issue 40) pp:11266-11273
Publication Date(Web):
DOI:10.1002/chem.201101394
Abstract
Four new uranium–ruthenium complexes, [(TrenTMS)URu(η5-C5H5)(CO)2] (9), [(TrenDMSB)URu(η5-C5H5)(CO)2] (10), [(TsTolyl)(THF)URu(η5-C5H5)(CO)2] (11), and [(TsXylyl)(THF)URu(η5-C5H5)(CO)2] (12) [TrenTMS=N(CH2CH2NSiMe3)3; TrenDMSB=N(CH2CH2NSiMe2tBu)3]; TsTolyl=HC(SiMe2NC6H4-4-Me)3; TsXylyl=HC(SiMe2NC6H3-3,5-Me2)3], were prepared by a salt-elimination strategy. Structural, spectroscopic, and computational analyses of 9–12 shows: i) the formation of unsupported uranium–ruthenium bonds with no isocarbonyl linkages in the solid state; ii) ruthenium–carbonyl backbonding in the [Ru(η5-C5H5)(CO)2]− ions that is tempered by polarization of charge within the ruthenium fragments towards uranium; iii) closed-shell uranium–ruthenium interactions that can be classified as predominantly ionic with little covalent character. Comparison of the calculated URu bond interaction energies (BIEs) of 9–12 with the BIE of [(η5-C5H5)3URu(η5-C5H5)(CO)2], for which an experimentally determined URu bond disruption enthalpy (BDE) has been reported, suggests BDEs of approximately 150 kJ mol−1 for 9–12.
Co-reporter:Benedict M. Gardner;Dr. Dipti Patel;Dr. William Lewis; Alexer J. Blake ;Dr. Stephen T. Liddle
Angewandte Chemie International Edition 2011 Volume 50( Issue 44) pp:10440-10443
Publication Date(Web):
DOI:10.1002/anie.201105098
Co-reporter:Benedict M. Gardner;Dr. Dipti Patel;Dr. William Lewis; Alexer J. Blake ;Dr. Stephen T. Liddle
Angewandte Chemie 2011 Volume 123( Issue 44) pp:10624-10627
Publication Date(Web):
DOI:10.1002/ange.201105098
Co-reporter:Oliver J. Cooper;Dr. David P. Mills;Dr. Jonathan McMaster;Dr. Fabrizio Moro;Dr. E. Stephen Davies;Dr. William Lewis; Alexer J. Blake ;Dr. Stephen T. Liddle
Angewandte Chemie 2011 Volume 123( Issue 10) pp:2431-2434
Publication Date(Web):
DOI:10.1002/ange.201007675
Co-reporter:Dr. Dipti Patel;Dr. Fabrizio Moro;Dr. Jonathan McMaster;Dr. William Lewis; Alexer J. Blake ;Dr. Stephen T. Liddle
Angewandte Chemie 2011 Volume 123( Issue 44) pp:10572-10576
Publication Date(Web):
DOI:10.1002/ange.201104110
Co-reporter:Ashley J. Wooles, Matthew Gregson, Sarah Robinson, Oliver J. Cooper, David P. Mills, William Lewis, Alexander J. Blake, and Stephen T. Liddle
Organometallics 2011 Volume 30(Issue 20) pp:5326-5337
Publication Date(Web):September 26, 2011
DOI:10.1021/om200729x
Treatment of H2C(PPh2NMes)2 (Mes = 2,4,6-trimethylphenyl) with 1 equiv of [Na(Bn)] (Bn = CH2C6H5) in THF gave the Lewis base adduct [Na{HC(PPh2NMes)2}(THF)2] (1). The heavy group 1 methanides [Rb{HC(PPh2NMes)2}(DME)2] (2) and [Cs{HC(PPh2NMes)2}]6 (3) were prepared by the reaction of [MOR] (M = Cs, Rb; OR = 2-ethylhexoxide) with [Li{HC(PPh2NMes)2}]. The Lewis base adduct 2 is monomeric, but 3 exists as a novel cyclic 2.9 nm hexamer in the solid state even though it was recrystallized from the strong donor solvent THF. The reaction of H2C(PPh2NDipp)2 (Dipp = 2,6-diisopropylphenyl) with [Na(Bn)] afforded [Na{HC(PPh2NDipp)2}(THF)] (4). The potassium congener [K{HC(PPh2NDipp)2}(THF)2] (5) was prepared by the reaction of the parent methane with KH. In 5, the methanide ligand is bound to potassium through one N center, the methanide center, and an η6-Dipp interaction. However, the THF molecules in 5 are loosely bound, as evidenced by the isolation of dimeric [{K[HC(PPh2NDipp)2](THF)}2] (6) from hexane. In 6, the potassium is bound to the two N centers of one methanide ligand, but no methanide–potassium interaction is observed, and a “loose” dimer is constructed by bridging K···CDipp interactions. The reaction of [MOR] (M = Rb, Cs) with [Li{HC(PPh2NDipp)2}] gave the heavy group 1 methanides [M{HC(PPh2NDipp)2}(THF)3] [M = Rb (7), Cs (8)]. The synthetic utility of these group 1 transfer agents has been demonstrated by the preparation of [Ln{HC(PPh2NMes)2}(I)2(THF)2] [Ln = Ce (9), Pr (10), Nd (11), Sm (12)] from [Ln(I)3(THF)n], employing a salt metathesis methodology. Complexes 1–12 have been characterized by X-ray crystallography, multielement NMR spectroscopy, FTIR spectroscopy, and CHN microanalyses.
Co-reporter:Ashley J. Wooles, Matthew Gregson, Oliver J. Cooper, Amy Middleton-Gear, David P. Mills, William Lewis, Alexander J. Blake, and Stephen T. Liddle
Organometallics 2011 Volume 30(Issue 20) pp:5314-5325
Publication Date(Web):September 26, 2011
DOI:10.1021/om200553s
Treatment of [Li{HC(PPh2NSiMe3)2}]2 with 2 equiv of [MOR] (M = Rb, Cs; OR = 2-ethylhexoxide) afforded the heavy group 1 methanides [Rb{HC(PPh2NSiMe3)2}(THF)2] (1) and [Cs{HC(PPh2NSiMe3)2}(DME)2] (2), which do not exhibit methanide C···M contacts in the solid state. Following a literature procedure, H2C(PPh2)2 was reacted with 2 equiv of AdN3 (Ad = adamantyl) to give H2C(PPh2NAd)2 (3). Reaction of 3 with 1 equiv of ButLi in toluene afforded dimeric [Li{HC(PPh2NAd)2}]2 (4). Treatment of 3 with 1 equiv of [M(Bn)] (M = Na, K; Bn = CH2C6H5) in THF gave the Lewis base adducts [M{HC(PPh2NAd)2}(THF)2] [M = Na (5), K (6)]. The heavy group 1 methanides [Rb{HC(PPh2NAd)2}(THF)2] (7) and [Cs{HC(PPh2NAd)2}(DME)2] (8) were prepared by the reaction of [MOR] (M = Rb, Cs; OR = 2-ethylhexoxide) with 4 or reaction of [Cs(Bn)] with 3. The synthetic utility of these group 1 transfer agents has been demonstrated by the preparation of [La{HC(PPh2NR)2}(I)2(THF)] [R = SiMe3 (9), Ad (10)] from [La(I)3(THF)4], employing a salt metathesis methodology. Complexes 1–10 have been characterized by X-ray crystallography, multielement NMR spectroscopy, FTIR spectroscopy, and CHN microanalyses.
Co-reporter:Oliver J. Cooper;Dr. David P. Mills;Dr. Jonathan McMaster;Dr. Fabrizio Moro;Dr. E. Stephen Davies;Dr. William Lewis; Alexer J. Blake ;Dr. Stephen T. Liddle
Angewandte Chemie International Edition 2011 Volume 50( Issue 10) pp:2383-2386
Publication Date(Web):
DOI:10.1002/anie.201007675
Co-reporter:Dr. Dipti Patel;Dr. Fabrizio Moro;Dr. Jonathan McMaster;Dr. William Lewis; Alexer J. Blake ;Dr. Stephen T. Liddle
Angewandte Chemie International Edition 2011 Volume 50( Issue 44) pp:10388-10392
Publication Date(Web):
DOI:10.1002/anie.201104110
Co-reporter:David P. Mills ; Lyndsay Soutar ; William Lewis ; Alexander J. Blake
Journal of the American Chemical Society 2010 Volume 132(Issue 41) pp:14379-14381
Publication Date(Web):September 27, 2010
DOI:10.1021/ja107958u
Rare earth carbenes exclusively exhibit Wittig-type reactivity with carbonyl compounds to afford alkenes. Here, we report that yttrium carbenes can effect regioselective ortho-C−H activation and sequential C−C and C−O bond formation reactions of aryl ketones to give iso-benzofurans and hydroxymethylbenzophenones. With MeCOPh, cyclotetramerization occurs giving a substituted cyclohexene. This demonstrates new rare earth carbene reactivity which complements existing Wittig-type reactivity.
Co-reporter:Oliver J. Cooper, Jonathan McMaster, William Lewis, Alexander J. Blake and Stephen T. Liddle
Dalton Transactions 2010 vol. 39(Issue 21) pp:5074-5076
Publication Date(Web):19 Apr 2010
DOI:10.1039/C0DT00152J
Treatment of H2C(PPh2NMes)2 (1, Mes = 2,4,6-Me3C6H2) with two equivalents of ButLi afforded the methandiide complex [Li2{C(PPh2NMes)2}2]2 (2); reaction of 2 with [UI3(THF)4] gave [U{C(PPh2NMes)2}2] (3), which is the first homoleptic uranium bis(carbene) complex with two formal UC double bonds.
Co-reporter:Ashley J. Wooles, David P. Mills, William Lewis, Alexander J. Blake and Stephen T. Liddle
Dalton Transactions 2010 vol. 39(Issue 2) pp:500-510
Publication Date(Web):27 Aug 2009
DOI:10.1039/B911717B
Reaction of [Ln(I)3(THF)4] (Ln = Ce, Pr) or [Ln(I)3(THF)3.5] (Ln = Nd, Sm, Gd, Dy, Er) with three equivalents of [KBz] (Bz = CH2C6H5) at 0 °C afforded the corresponding lanthanide tri-benzyl complexes [Ln(Bz)3(THF)3] [Ln = Ce (2), Pr (3), Nd (4), Sm (5), Gd (6), Dy (7), Er (8) La (11)] in 48–75% crystalline yields, with the exception of the redox active samarium complex, which was isolated in poor (20%) yield. Complexes 2–8 were found to adopt distorted octahedral geometries, where the Bz and THF groups are bound in a mutually fac manner in the solid state. Although the series is structurally similar, classification of three structural types can be made on the basis of the lanthanide contraction: (i) complexes which exhibit three η2 Ln⋯Cipso contacts (1–4, 11); (ii) complexes which show one η2 Ln⋯Cipso contact (5); (iii) complexes with no multi-hapto interactions (6–8). For ytterbium, the mixed valence, YbII/YbIII complex [YbII(Bz)(THF)5]+[YbIII(Bz)4(THF)2]− (9) was reproducibly formed at 0 °C and −78 °C as a result of partial (50%) YbIII→ YbII reduction with concomitant formation of half an equivalent of 1,2-diphenylethane by oxidative coupling. Tri-valent [Yb(Bz)3(THF)3] (10) was apparently not formed. The synthetic utility of tri-benzyl lanthanide complexes 2–8 and 11 were tested in reactions with the bis-(iminophosphorano)methane H2C(PPh2NSiMe3)2 (H2-BIPM), which afforded [Ln(BIPM)(H-BIPM)] [Ln = La (12), Ce (13), Pr (14), Nd (15), Sm (16), Gd (17)] and [Ln(BIPM)(Bz)(THF)] [Ln = Dy (18), Er (19)]. Compounds 2–9 and 12–19 have been variously characterised by X-ray crystallography, multi-nuclear NMR spectroscopy, FTIR spectroscopy, room temperature Evans method solution magnetic moments and CHN micro-analyses.
Co-reporter:Dipti Patel, William Lewis, Alexander J. Blake and Stephen T. Liddle
Dalton Transactions 2010 vol. 39(Issue 29) pp:6638-6647
Publication Date(Web):12 Mar 2010
DOI:10.1039/B926018H
Reaction of three equivalents of ArNH2 (Ar = 3,5-Me2C6H3) with HC(SiMe2Br)3 in the presence of the auxiliary base NEt3 afforded the tripodal tris(N-arylamine-dimethylsilyl)methane HC{SiMe2N(H)Ar}3 (1) in 83% yield. Three-fold deprotonation of 1 with n-butyllithium afforded the corresponding tri-lithium tris(N-arylamido-dimethylsilyl)methane etherate [HC{SiMe2N(Li)Ar}3(OEt2)] (2) in 92% yield. Salt elimination reactions between 2 or the known complex [HC{SiMe2N(Li)Ar′}3(OEt2)2] (3) (Ar′ = 4-MeC6H4) with one equivalent of uranium(IV) tetrachloride afforded the corresponding tris(N-arylamido-dimethylsilyl)methane uranium(IV) chloride complexes as monomeric [U(Cl){HC(SiMe2NAr)3}(THF)] (4) and dinuclear [{HC(SiMe2NAr′)3}U(Cl)(μ-Cl)U(THF)2{(Ar′NSiMe2)3CH}] (5) species in 70 and 90% crystalline yields, respectively. Treatment of 4 and 5 with one equivalent of trimethylsilyl iodide resulted in halide exchange and formation of [U(I){HC(SiMe2NAr)3}(THF)2] (6) and [U(I){HC(SiMe2NAr′)3}(THF)] (7) in 85 and 90% yields, respectively. The heteroleptic amide [U(NCy2){HC(SiMe2NAr)3}(THF)] (8) was prepared from the reaction between 4 and one equivalent of lithium dicyclohexylamide and was isolated in 78% yield. Analogous attempts to prepare [U(NCy2){HC(SiMe2NAr′)3}(THF)] (9) from 5 consistently resulted in intractable mixtures of products. Complexes 1–8 have been characterised by X-ray crystallography, NMR spectroscopy, FTIR spectroscopy, room temperature Evans method solution magnetic moments, and CHN micro-analyses.
Co-reporter:Ashley J. Wooles, Oliver J. Cooper, Jonathan McMaster, William Lewis, Alexander J. Blake and Stephen T. Liddle
Organometallics 2010 Volume 29(Issue 10) pp:2315-2321
Publication Date(Web):April 20, 2010
DOI:10.1021/om100104s
Attempts to prepare [Dy{C(PPh2NSiMe3)2}(I)(THF)2] (1) from in situ prepared “[Dy(Bn)2(I)(THF)3]” (“2”; Bn = C6H5CH2) and H2C(PPh2NSiMe3)2 resulted in the isolation of [Dy{CH(PPh2NSiMe3)2}(I)2(THF)] (3) and, on one occasion, a small quantity of [{Dy(CH[PPh2NSiMe3]2)(I)}2(μ-O)] (4). However, attempts to prepare 3 from [K{CH(PPh2NSiMe3)2}(THF)n] and [Dy(I)3(THF)3.5] were unsuccessful. The corresponding reactions with [La(I)3(THF)4] were unsuccessful, and the reaction of [{Li2(C[PPh2NSiMe3]2)}2] and [La(I)3(THF)4] in a 1:1 ratio resulted in the isolation of [{La(μ-I)3Li(THF)2}2{μ-C(PPh2NSiMe3)2}] (5). However, the potassium methanide complex [K{CH(PPh2NMes)2}] (Mes = 2,4,6-Me3C6H2) was found to react with [La(I)3(THF)4] to give [La{CH(PPh2NMes)2}(I)2(THF)2] (6). Complex 6 reacts with 1 equiv of [K(Bn)] to afford the methanediide complex [La{C(PPh2NMes)2}(I)(THF)3] (7). A DFT study of 6 and 7 revealed an increased accumulation of charge at the endocyclic carbon following deprotonation and conversion of 6 to 7, and although the La−C bond indices increase substantially upon a second deprotonation, the bonding remains highly ionic and is dominated by carbon 2p contributions with little orbital contribution from lanthanum. Compounds 1−7 have been variously characterized by X-ray crystallography, NMR spectroscopy, FTIR spectroscopy, CHN microanalyses, room-temperature solution magnetic moments, and, for 6 and 7, DFT calculations.
Co-reporter:Thomas Pell, David P. Mills, Alexander J. Blake, William Lewis, Stephen T. Liddle
Polyhedron 2010 29(1) pp: 120-125
Publication Date(Web):
DOI:10.1016/j.poly.2009.06.011
Co-reporter:OliverJ. Cooper;AshleyJ. Wooles;Jonathan McMaster Dr.;William Lewis Dr.;AlexerJ. Blake ;StephenT. Liddle Dr.
Angewandte Chemie 2010 Volume 122( Issue 32) pp:5702-5705
Publication Date(Web):
DOI:10.1002/ange.201002483
Co-reporter:OliverJ. Cooper;AshleyJ. Wooles;Jonathan McMaster Dr.;William Lewis Dr.;AlexerJ. Blake ;StephenT. Liddle Dr.
Angewandte Chemie International Edition 2010 Volume 49( Issue 32) pp:5570-5573
Publication Date(Web):
DOI:10.1002/anie.201002483
Co-reporter:Benedict M. Gardner ; Jonathan McMaster ; William Lewis ; Alexander J. Blake
Journal of the American Chemical Society 2009 Volume 131(Issue 30) pp:10388-10389
Publication Date(Web):July 8, 2009
DOI:10.1021/ja904459q
The unprecedented formation of a dinuclear tuck-in-tuck-over tuck-over dialkyl Tren-uranium(IV) complex and the first example of double dearylation of BPh4− in a molecular context to give a BPh2-functionalized uranium metallocycle are reported.
Co-reporter:Benedict M. Gardner, Jonathan McMaster, William Lewis and Stephen T. Liddle
Chemical Communications 2009 (Issue 20) pp:2851-2853
Publication Date(Web):24 Apr 2009
DOI:10.1039/B906554G
The first structurally authenticated molecular uranium–transition metal bond is reported; DFT studies show σ- and π-components in the U–Re bond and this is the first time that the latter component has been reported in an unsupported f-element–transition metal bond.
Co-reporter:Stephen T. Liddle, David P. Mills, Benedict M. Gardner, Jonathan McMaster, Cameron Jones and William D. Woodul
Inorganic Chemistry 2009 Volume 48(Issue 8) pp:3520-3522
Publication Date(Web):March 13, 2009
DOI:10.1021/ic900278t
The synthesis and characterization of the first unsupported Ga−Y bond in [Y{Ga(NArCH)2}{C(PPh2NSiMe3)2}(THF)2] (Ar = 2,6-diisopropylphenyl) is described; structural and computational analyses are consistent with a highly polarized covalent Ga−Y bond.
Co-reporter:David P. Mills, Oliver J. Cooper, Jonathan McMaster, William Lewis and Stephen T. Liddle
Dalton Transactions 2009 (Issue 23) pp:4547-4555
Publication Date(Web):24 Apr 2009
DOI:10.1039/B902079A
Reaction of [YI3(THF)3.5] with three equivalents of [KBz] (Bz = CH2C6H5) affords the tri-benzyl complex [Y(Bz)3(THF)3] (2) in excellent yield. Complex 2 reacts with H2C(PPh2NSiMe3)2 (H2BIPM) to afford the yttrium-alkyl-carbene complex [Y(BIPM)(Bz)(THF)] (3, BIPM = {C(PPh2NSiMe3)2}). Compound 3 reacts with one equivalent of benzophenone to give the alkoxy 1,2-migratory insertion product [Y(BIPM)(OCPh2Bz)(THF)] (4) rather than the alkene Wittig-product Ph2CC(PPh2NSiMe3)2. Reaction of 4 with one or more equivalents of benzophenone does not afford any detectable alkene products, rather it apparently catalyses rearrangement of monomeric 4 to afford dimeric [{Y(μ-BIPM)(OCPh2Bz)}2] (5). Investigations reveal that formation of 5 is proportional to the amount of benzophenone added, but the benzophenone is recovered at the end of the reaction. Reaction of 3 with diphenyldiazene affords the 1,2-migratory insertion product [Y(BIPM){N(Ph)N(Ph)(Bz)}(THF)] (6) Compounds 2, 3, 4, 5, and 6 have been variously characterised by X-ray crystallography, multi-nuclear NMR spectroscopy, FTIR spectroscopy, and CHN micro-analyses. Density functional theory calculations on 3 reveal the HOMO to be localised at the Y–Calkyl bond which is commensurate with the observed reactivity.
Co-reporter:Stephen T. Liddle and David P. Mills
Dalton Transactions 2009 (Issue 29) pp:5592-5605
Publication Date(Web):06 May 2009
DOI:10.1039/B904318G
The molecular chemistry of the f-elements is traditionally dominated by the use of carbon-, nitrogen-, oxygen-, or halide-ligands. However, the use of metal-based fragments as ligands is underdeveloped, which contrasts to the fields of d- and p-block metal–metal complexes that have developed extensively over the last fifty years. This perspective outlines the development of compounds, which possess polarised covalent or donor–acceptor f-element–metal bonds. For this review, the f-element is defined as (i) a group 3 or lanthanide metal: scandium, yttrium, lanthanum to lutetium, or (ii) an actinide metal: thorium, or uranium, and the metal is defined as a d-block transition metal, or a group 13 (aluminium or gallium), a group 14 (silicon, germanium, or tin), or a group 15 (antimony, or bismuth) metal. Silicon, germanium, and antimony are traditionally classified as metalloids but they are included for completeness. This review focuses mainly on complexes that have been structurally authenticated by single-crystal X-ray diffraction studies and we highlight novel aspects of their syntheses, properties, and reactivities.
Co-reporter:Benedict M. Gardner, Jonathan McMaster and Stephen T. Liddle
Dalton Transactions 2009 (Issue 35) pp:6924-6926
Publication Date(Web):30 Apr 2009
DOI:10.1039/B906000F
Treatment of UCl4 with one or two equivalents of IPr [IPr = {C(NArCH)2}, Ar = 2,6-diisopropylphenyl] gives [UCl4(IPr)2] as the sole isolable uranium-containing containing product; an X-ray diffraction study showed close Cl⋯Ccarbene contacts, but DFT analysis suggests the contacts are the result of aryl chloride steric repulsions as the Cl⋯C orbital interaction is negligible.
Co-reporter:StephenT. Liddle Dr.;Jonathan McMaster Dr.;DavidP. Mills Dr.;AlexerJ. Blake ;Cameron Jones ;WilliamD. Woodul Dr.
Angewandte Chemie 2009 Volume 121( Issue 6) pp:1097-1100
Publication Date(Web):
DOI:10.1002/ange.200805481
Co-reporter:David P. Mills, Ashley J. Wooles, Jonathan McMaster, William Lewis, Alexander J. Blake and Stephen T. Liddle
Organometallics 2009 Volume 28(Issue 23) pp:6771-6776
Publication Date(Web):October 6, 2009
DOI:10.1021/om9007949
Heteroleptic dibenzyl yttrium and erbium iodides [Ln(Bn)2(I)(THF)3] [Ln = Y (1), Er (2); Bn = CH2C6H5] were prepared in high yields and are remarkable for their thermal stability and inertness toward ligand scrambling in Schlenk-type equilibria. A variable-temperature study of 1 revealed a dynamic process in solution attributed to the presence of three isomers, namely, cis-fac, cis-mer, and trans-mer, which were observed in a 0.11:1:0.05 ratio at 298 K, respectively. Only the isomer attributed as cis-mer was observed at 313 K. The synthetic utility of 1 and 2, which combines the potential benefits of protonolysis and salt elimination chemistry, was demonstrated by the facile synthesis of phosphorus-stabilized yttrium and erbium carbenes [Ln(BIPM)(I)(THF)2] [Ln = Y (3); Er (4); BIPM = {C(PPh2NSiMe3)}2−], which each contain unusual T-shaped carbene centers. DFT calculations on 3, BIPM, and Ph3P═C═PPh3 showed very similar frontier orbital compositions in all three examples. Although 3 and 4 are classified as carbene complexes, and NBO analysis is consistent with the BIPM ligand adopting the dipolar N−-P+-C2−-P+-N− resonance form, the possibility of categorizing 3 and 4 as captodative carbon(0) complexes of yttrium and erbium cannot be ruled out. Complexes 1−4 have been variously characterized by X-ray crystallography, multinuclear NMR spectroscopy, FTIR spectroscopy, room-temperature Evans method solution magnetic moments, and CHN microanalyses.
Co-reporter:StephenT. Liddle Dr.;Jonathan McMaster Dr.;DavidP. Mills Dr.;AlexerJ. Blake ;Cameron Jones ;WilliamD. Woodul Dr.
Angewandte Chemie International Edition 2009 Volume 48( Issue 6) pp:1077-1080
Publication Date(Web):
DOI:10.1002/anie.200805481
Co-reporter:Stephen T. Liddle, Benedict M. Gardner
Journal of Organometallic Chemistry 2009 694(9–10) pp: 1581-1585
Publication Date(Web):
DOI:10.1016/j.jorganchem.2009.01.029
Co-reporter:Stephen T. Liddle, Jonathan McMaster, Jennifer C. Green and Polly L. Arnold
Chemical Communications 2008 (Issue 15) pp:1747-1749
Publication Date(Web):08 Feb 2008
DOI:10.1039/B719633D
The first structurally authenticated yttrium-alkyl-alkylidene is reported; structural, spectroscopic, and theoretical analyses show that whilst the yttrium-alkylidene bond is short, it possesses a bond order less than one and is comparable to the Y–Calkyl single bond within the same molecule.
Co-reporter:Oliver J. Cooper, David P. Mills, William Lewis, Alexander J. Blake and Stephen T. Liddle
Dalton Transactions 2014 - vol. 43(Issue 38) pp:NaN14283-14283
Publication Date(Web):2014/04/25
DOI:10.1039/C4DT00909F
The reactivity of the uranium(IV) carbene complex [U(BIPMTMS)(Cl)(μ-Cl)2Li(THF)2] (1, BIPMTMS = {C(PPh2NSiMe3)2}) towards carbonyl and heteroallene substrates is reported. Reaction of 1 with benzophenone proceeds to give the metallo-Wittig terminal alkene product Ph2CC(PPh2NSiMe3)2 (2); the likely “UOCl2” byproduct could not be isolated. Addition of the bulky ketone PhCOBut to 1 resulted in loss of LiCl, coordination of the ketone, and dimerisation to give [U(BIPMTMS)(Cl)(μ-Cl){OC(Ph)(But)}]2 (3). The reaction of 1 with coumarin resulted in ring opening of the cyclic ester and a metallo-Wittig-type reaction to afford [U{BIPMTMS[C(O)(CHCHC6H4O-2)]-κ3-N,O,O′}(Cl)2(THF)] (4) where the enolate product remains coordinated to uranium. The reaction of PhCOF with 1 resulted in C–F bond activation and oxidation resulting in isolation of [U(O)2(Cl)2(μ-Cl)2{(μ-LiDME)OC(Ph)C(PPh2NSiMe3)(PPh2NHSiMe3)}2] (5) along with [U(Cl)2(F)2(py)4] (6). The reactions of 1 with tert-butylisocyanate or dicyclohexylcarbodiimide resulted in the isolation of the [2 + 2]-cycloaddition products [U{BIPMTMS[C(NBut){OLi(THF)2(μ-Cl)Li(THF)3}]-κ4-C,N,N′,N′′}(Cl)3] (7) and [U{BIPMTMS[C(NCy)2]-κ4-C,N,N′,N′′}(Cl)(μ-Cl)2Li(THF)2] (8). Complexes 2–8 have been variously characterised by single crystal X-ray diffraction, multi-nuclear NMR and FTIR spectroscopies, Evans method solution magnetic moments, variable temperature SQUID magnetometry, and elemental analyses.
Co-reporter:Benedict M. Gardner, Jonathan McMaster and Stephen T. Liddle
Dalton Transactions 2009(Issue 35) pp:NaN6926-6926
Publication Date(Web):2009/04/30
DOI:10.1039/B906000F
Treatment of UCl4 with one or two equivalents of IPr [IPr = {C(NArCH)2}, Ar = 2,6-diisopropylphenyl] gives [UCl4(IPr)2] as the sole isolable uranium-containing containing product; an X-ray diffraction study showed close Cl⋯Ccarbene contacts, but DFT analysis suggests the contacts are the result of aryl chloride steric repulsions as the Cl⋯C orbital interaction is negligible.
Co-reporter:Stephen T. Liddle and Joris van Slageren
Chemical Society Reviews 2015 - vol. 44(Issue 19) pp:NaN6669-6669
Publication Date(Web):2015/07/09
DOI:10.1039/C5CS00222B
Ever since the discovery that certain manganese clusters retain their magnetisation for months at low temperatures, there has been intense interest in molecular nanomagnets because of potential applications in data storage, spintronics, quantum computing, and magnetocaloric cooling. In this Tutorial Review, we summarise some key historical developments, and centre our discussion principally on the increasing trend to exploit the large magnetic moments and anisotropies of f-element ions. We focus on the important theme of strategies to improve these systems with the ultimate aim of developing materials for ultra-high-density data storage devices. We present a critical discussion of key parameters to be optimised, as well as of experimental and theoretical techniques to be used to this end.
Co-reporter:David P. Mills, Oliver J. Cooper, Jonathan McMaster, William Lewis and Stephen T. Liddle
Dalton Transactions 2009(Issue 23) pp:NaN4555-4555
Publication Date(Web):2009/04/24
DOI:10.1039/B902079A
Reaction of [YI3(THF)3.5] with three equivalents of [KBz] (Bz = CH2C6H5) affords the tri-benzyl complex [Y(Bz)3(THF)3] (2) in excellent yield. Complex 2 reacts with H2C(PPh2NSiMe3)2 (H2BIPM) to afford the yttrium-alkyl-carbene complex [Y(BIPM)(Bz)(THF)] (3, BIPM = {C(PPh2NSiMe3)2}). Compound 3 reacts with one equivalent of benzophenone to give the alkoxy 1,2-migratory insertion product [Y(BIPM)(OCPh2Bz)(THF)] (4) rather than the alkene Wittig-product Ph2CC(PPh2NSiMe3)2. Reaction of 4 with one or more equivalents of benzophenone does not afford any detectable alkene products, rather it apparently catalyses rearrangement of monomeric 4 to afford dimeric [{Y(μ-BIPM)(OCPh2Bz)}2] (5). Investigations reveal that formation of 5 is proportional to the amount of benzophenone added, but the benzophenone is recovered at the end of the reaction. Reaction of 3 with diphenyldiazene affords the 1,2-migratory insertion product [Y(BIPM){N(Ph)N(Ph)(Bz)}(THF)] (6) Compounds 2, 3, 4, 5, and 6 have been variously characterised by X-ray crystallography, multi-nuclear NMR spectroscopy, FTIR spectroscopy, and CHN micro-analyses. Density functional theory calculations on 3 reveal the HOMO to be localised at the Y–Calkyl bond which is commensurate with the observed reactivity.
Co-reporter:Oliver J. Cooper, Jonathan McMaster, William Lewis, Alexander J. Blake and Stephen T. Liddle
Dalton Transactions 2010 - vol. 39(Issue 21) pp:NaN5076-5076
Publication Date(Web):2010/04/19
DOI:10.1039/C0DT00152J
Treatment of H2C(PPh2NMes)2 (1, Mes = 2,4,6-Me3C6H2) with two equivalents of ButLi afforded the methandiide complex [Li2{C(PPh2NMes)2}2]2 (2); reaction of 2 with [UI3(THF)4] gave [U{C(PPh2NMes)2}2] (3), which is the first homoleptic uranium bis(carbene) complex with two formal UC double bonds.
Co-reporter:Dipti Patel, Floriana Tuna, Eric J. L. McInnes, Jonathan McMaster, William Lewis, Alexander J. Blake and Stephen T. Liddle
Dalton Transactions 2013 - vol. 42(Issue 15) pp:NaN5227-5227
Publication Date(Web):2013/02/20
DOI:10.1039/C3DT50255D
Reduction of [U(TsTol)(Cl)(μ-Cl)U(TsTol)(THF)2] [2, TsTol = HC(SiMe2NAr′)3; Ar′ = 4-MeC6H4)] with KC8 in toluene afforded the new arene-bridged diuranium complex [{U(TsTol)}2(μ–η6:η6-C6H5Me)] (3); combined structural, spectroscopic, magnetic, and computational analyses unambiguously confirm that the uranium centres in 3 are in the +5 oxidation state and the toluene is a 10π-tetraanion.
Co-reporter:Benedict M. Gardner and Stephen T. Liddle
Chemical Communications 2015 - vol. 51(Issue 53) pp:NaN10607-10607
Publication Date(Web):2015/06/02
DOI:10.1039/C5CC01360G
Triamidoamine (Tren) complexes of the p- and d-block elements have been well-studied, and they display a diverse array of chemistry of academic, industrial and biological significance. Such in-depth investigations are not as widespread for Tren complexes of uranium, despite the general drive to better understand the chemical behaviour of uranium by virtue of its fundamental position within the nuclear sector. However, the chemistry of Tren–uranium complexes is characterised by the ability to stabilise otherwise reactive, multiply bonded main group donor atom ligands, construct uranium–metal bonds, promote small molecule activation, and support single molecule magnetism, all of which exploit the steric, electronic, thermodynamic and kinetic features of the Tren ligand system. This Feature Article presents a current account of the chemistry of Tren–uranium complexes.
Co-reporter:Dipti Patel, William Lewis, Alexander J. Blake and Stephen T. Liddle
Dalton Transactions 2010 - vol. 39(Issue 29) pp:NaN6647-6647
Publication Date(Web):2010/03/12
DOI:10.1039/B926018H
Reaction of three equivalents of ArNH2 (Ar = 3,5-Me2C6H3) with HC(SiMe2Br)3 in the presence of the auxiliary base NEt3 afforded the tripodal tris(N-arylamine-dimethylsilyl)methane HC{SiMe2N(H)Ar}3 (1) in 83% yield. Three-fold deprotonation of 1 with n-butyllithium afforded the corresponding tri-lithium tris(N-arylamido-dimethylsilyl)methane etherate [HC{SiMe2N(Li)Ar}3(OEt2)] (2) in 92% yield. Salt elimination reactions between 2 or the known complex [HC{SiMe2N(Li)Ar′}3(OEt2)2] (3) (Ar′ = 4-MeC6H4) with one equivalent of uranium(IV) tetrachloride afforded the corresponding tris(N-arylamido-dimethylsilyl)methane uranium(IV) chloride complexes as monomeric [U(Cl){HC(SiMe2NAr)3}(THF)] (4) and dinuclear [{HC(SiMe2NAr′)3}U(Cl)(μ-Cl)U(THF)2{(Ar′NSiMe2)3CH}] (5) species in 70 and 90% crystalline yields, respectively. Treatment of 4 and 5 with one equivalent of trimethylsilyl iodide resulted in halide exchange and formation of [U(I){HC(SiMe2NAr)3}(THF)2] (6) and [U(I){HC(SiMe2NAr′)3}(THF)] (7) in 85 and 90% yields, respectively. The heteroleptic amide [U(NCy2){HC(SiMe2NAr)3}(THF)] (8) was prepared from the reaction between 4 and one equivalent of lithium dicyclohexylamide and was isolated in 78% yield. Analogous attempts to prepare [U(NCy2){HC(SiMe2NAr′)3}(THF)] (9) from 5 consistently resulted in intractable mixtures of products. Complexes 1–8 have been characterised by X-ray crystallography, NMR spectroscopy, FTIR spectroscopy, room temperature Evans method solution magnetic moments, and CHN micro-analyses.
Co-reporter:Sarah Robinson, Jonathan McMaster, William Lewis, Alexander J. Blake and Stephen T. Liddle
Chemical Communications 2012 - vol. 48(Issue 46) pp:NaN5771-5771
Publication Date(Web):2012/04/30
DOI:10.1039/C2CC31758C
Reaction of lithium with PDABBr [PDA = C6H4-1,2-(NTripp)2, Tripp = 2,4,6-Pri3C6H2] and naphthalene afforded 2- and 2,6-borylated naphthalenes; conversely, use of high-sodium lithium (0.5% Na) afforded the lithium boryl [(PDAB)Li(THF)2]; this work establishes that main group reagents can achieve selective borylations of fused polycyclic aromatics under mild conditions in good yields.
Co-reporter:Benedict M. Gardner, Peter A. Cleaves, Christos E. Kefalidis, Jian Fang, Laurent Maron, William Lewis, Alexander J. Blake and Stephen T. Liddle
Chemical Science (2010-Present) 2014 - vol. 5(Issue 6) pp:NaN2497-2497
Publication Date(Web):2014/02/26
DOI:10.1039/C4SC00182F
We report on the role of 5f-orbital participation in the unexpected inversion of the σ-bond metathesis reactivity trend of triamidoamine thorium(IV) and uranium(IV) alkyls. Reaction of KCH2Ph with [U(TrenTIPS)(I)] [2a, TrenTIPS = N(CH2CH2NSiPri3)33−] gave the cyclometallate [U{N(CH2CH2NSiPri3)2(CH2CH2NSiPri2C[H]MeCH2)}] (3a) with the intermediate benzyl complex not observable. In contrast, when [Th(TrenTIPS)(I)] (2b) was treated with KCH2Ph, [Th(TrenTIPS)(CH2Ph)] (4) was isolated; which is notable as Tren N-silylalkyl metal alkyls tend to spontaneously cyclometallate. Thermolysis of 4 results in the extrusion of toluene and formation of the cyclometallate [Th{N(CH2CH2NSiPri3)2(CH2CH2NSiPri2C[H]MeCH2)}] (3b). This reactivity is the reverse of what would be predicted. Since the bonding of thorium is mainly electrostatic it would be predicted to undergo facile cyclometallation, whereas the more covalent uranium system might be expected to form an isolable benzyl intermediate. The thermolysis of 4 follows well-defined first order kinetics with an activation energy of 22.3 ± 0.1 kcal mol−1, and Eyring analyses yields ΔH‡ = 21.7 ± 3.6 kcal mol−1 and ΔS‡ = −10.5 ± 3.1 cal K−1 mol−1, which is consistent with a σ-bond metathesis reaction. Computational examination of the reaction profile shows that the inversion of the reactivity trend can be attributed to the greater f-orbital participation of the bonding for uranium facilitating the σ-bond metathesis transition state whereas for thorium the transition state is more ionic resulting in an isolable benzyl complex. The activation barriers are computed to be 19.0 and 22.2 kcal mol−1 for the uranium and thorium cases, respectively, and the latter agrees excellently with the experimental value. Reductive decomposition of “[U(TrenTIPS)(CH2Ph)]” to [U(TrenTIPS)] and bibenzyl followed by cyclometallation to give 3a with elimination of dihydrogen was found to be endergonic by 4 kcal mol−1 which rules out a redox-based cyclometallation route for uranium.
Co-reporter:Sarah Robinson, E. Stephen Davies, William Lewis, Alexander J. Blake and Stephen T. Liddle
Dalton Transactions 2014 - vol. 43(Issue 11) pp:NaN4360-4360
Publication Date(Web):2013/10/31
DOI:10.1039/C3DT52632A
Treatment of the ortho-phenylene diamine C6H4-1,2-{N(H)Tripp}2 (1, PDAH2, Tripp = 2,4,6-triisopropylphenyl) with two equivalents of MR (M = Li, R = Bun; M = Na or K, R = CH2C6H5) afforded the dimetallated alkali metal ortho-phenylene diamide dianion complexes [(PDALi2)(THF)3] (2), [{(PDANa2)(THF)2}2] (3), and [{(PDAK2)(THF)3}2] (4). In contrast, treatment of 2 with two equivalents of rubidium or cesium 2-ethylhexoxide, or treatment of 1 with two equivalents of MR (M = Rb or Cs, R = CH2C6H5) did not afford the anticipated dialkali metal ortho-phenylene diamide dianion derivatives and instead formally afforded the monometallic ortho-diiminosemiquinonate radical anion species [PDAM] (M = Rb, 5; M = Cs, 6). The structure of 2 is monomeric with one lithium coordinated to the two nitrogen centres and the other lithium η4-coordinated to the diazabutadiene portion of the PDA scaffold. Similar structural cores are observed for 3 and 4, except that the larger sodium and potassium ions give dimeric structures linked by multi-hapto interactions from the PDA backbone phenyl ring to an alkali metal centre. Complex 5 was not characterised in the solid state, but the structure of 6 reveals coordination of cesium ions to both PDA amide centres and multi-hapto interactions to a PDA backbone phenyl ring in the next unit to generate a one-dimensional polymer. Complexes 2–6 have been variously characterised by X-ray crystallography, multi-nuclear NMR, FTIR, and EPR spectroscopies, and CHN microanalyses.
Co-reporter:Ashley J. Wooles, David P. Mills, William Lewis, Alexander J. Blake and Stephen T. Liddle
Dalton Transactions 2010 - vol. 39(Issue 2) pp:NaN510-510
Publication Date(Web):2009/08/27
DOI:10.1039/B911717B
Reaction of [Ln(I)3(THF)4] (Ln = Ce, Pr) or [Ln(I)3(THF)3.5] (Ln = Nd, Sm, Gd, Dy, Er) with three equivalents of [KBz] (Bz = CH2C6H5) at 0 °C afforded the corresponding lanthanide tri-benzyl complexes [Ln(Bz)3(THF)3] [Ln = Ce (2), Pr (3), Nd (4), Sm (5), Gd (6), Dy (7), Er (8) La (11)] in 48–75% crystalline yields, with the exception of the redox active samarium complex, which was isolated in poor (20%) yield. Complexes 2–8 were found to adopt distorted octahedral geometries, where the Bz and THF groups are bound in a mutually fac manner in the solid state. Although the series is structurally similar, classification of three structural types can be made on the basis of the lanthanide contraction: (i) complexes which exhibit three η2 Ln⋯Cipso contacts (1–4, 11); (ii) complexes which show one η2 Ln⋯Cipso contact (5); (iii) complexes with no multi-hapto interactions (6–8). For ytterbium, the mixed valence, YbII/YbIII complex [YbII(Bz)(THF)5]+[YbIII(Bz)4(THF)2]− (9) was reproducibly formed at 0 °C and −78 °C as a result of partial (50%) YbIII→ YbII reduction with concomitant formation of half an equivalent of 1,2-diphenylethane by oxidative coupling. Tri-valent [Yb(Bz)3(THF)3] (10) was apparently not formed. The synthetic utility of tri-benzyl lanthanide complexes 2–8 and 11 were tested in reactions with the bis-(iminophosphorano)methane H2C(PPh2NSiMe3)2 (H2-BIPM), which afforded [Ln(BIPM)(H-BIPM)] [Ln = La (12), Ce (13), Pr (14), Nd (15), Sm (16), Gd (17)] and [Ln(BIPM)(Bz)(THF)] [Ln = Dy (18), Er (19)]. Compounds 2–9 and 12–19 have been variously characterised by X-ray crystallography, multi-nuclear NMR spectroscopy, FTIR spectroscopy, room temperature Evans method solution magnetic moments and CHN micro-analyses.
Co-reporter:Dipti Patel, David M. King, Benedict M. Gardner, Jonathan McMaster, William Lewis, Alexander J. Blake and Stephen T. Liddle
Chemical Communications 2011 - vol. 47(Issue 1) pp:NaN297-297
Publication Date(Web):2010/08/05
DOI:10.1039/C0CC01387K
Amine-elimination gave the two uranium–rhenium complexes [(TsXy)(THF)nURe(η5-C5H5)2] [TsXy = HC(SiMe2N-3,5-Me2C6H3)3; n = 0 or 1]; structural and theoretical analyses, and comparison to [(TrenTMS)URe(η5-C5H5)2] [TrenTMS = N(CH2CH2NSiMe3)3], reveal an increasing σ-component to the U–Re bond upon removal of dative ancillary ligands from uranium with the π-component remaining essentially invariant.
Co-reporter:Stephen T. Liddle, David P. Mills and Ashley J. Wooles
Chemical Society Reviews 2011 - vol. 40(Issue 5) pp:NaN2176-2176
Publication Date(Web):2011/02/14
DOI:10.1039/C0CS00135J
Since the discovery of covalently-bound mid- and late-transition metal carbenes there has been a spectacular explosion of interest in their chemistry, but their early metal counterparts have lagged behind. In recent years, bis(phosphorus-stabilised)carbenes have emerged as valuable ligands for metals across the periodic table, and their use has in particular greatly expanded covalently-bound early metal carbene chemistry. In this tutorial review we introduce the reader to bis(phosphorus-stabilised)carbenes, and cover general preparative methods, structure and bonding features, and emerging reactivity studies of early metal derivatives (groups 1–4 and the f-elements).
Co-reporter:Erli Lu and Stephen T. Liddle
Dalton Transactions 2015 - vol. 44(Issue 29) pp:NaN12941-12941
Publication Date(Web):2015/06/23
DOI:10.1039/C5DT00608B
Oxidative addition, and its reverse reaction reductive elimination, constitute two key reactions that underpin organometallic chemistry and catalysis. Although these reactions have been known for decades in main group and transition metal systems, they are exceptionally rare or unknown for the f-block. However, in recent years much progress has been made. In this Perspective article, advances in uranium-mediated oxidative addition/reductive elimination, since the point that this research area was initiated in the early-1980s, are summarised. We principally divide the Perspective into two parts of oxidative addition and reductive elimination, along with a separate section concerning reactions where there is no change of uranium oxidation state in reactant and product but the reaction has the formal appearance of a ‘concerted’ reductive elimination/oxidative addition from the perspective of the net result. This body of work highlights that whilst uranium is capable of performing reactions that to some extent conform to traditional reactivity types, novel reactivity that has no counterpart anywhere else can be performed, thus adding to the rich palate of redox chemistry that uranium can mediate.
Co-reporter:Benedict M. Gardner, Jonathan McMaster, William Lewis and Stephen T. Liddle
Chemical Communications 2009(Issue 20) pp:NaN2853-2853
Publication Date(Web):2009/04/24
DOI:10.1039/B906554G
The first structurally authenticated molecular uranium–transition metal bond is reported; DFT studies show σ- and π-components in the U–Re bond and this is the first time that the latter component has been reported in an unsupported f-element–transition metal bond.
Co-reporter:Stephen T. Liddle, Jonathan McMaster, Jennifer C. Green and Polly L. Arnold
Chemical Communications 2008(Issue 15) pp:NaN1749-1749
Publication Date(Web):2008/02/08
DOI:10.1039/B719633D
The first structurally authenticated yttrium-alkyl-alkylidene is reported; structural, spectroscopic, and theoretical analyses show that whilst the yttrium-alkylidene bond is short, it possesses a bond order less than one and is comparable to the Y–Calkyl single bond within the same molecule.
Co-reporter:Stephen T. Liddle and David P. Mills
Dalton Transactions 2009(Issue 29) pp:NaN5605-5605
Publication Date(Web):2009/05/06
DOI:10.1039/B904318G
The molecular chemistry of the f-elements is traditionally dominated by the use of carbon-, nitrogen-, oxygen-, or halide-ligands. However, the use of metal-based fragments as ligands is underdeveloped, which contrasts to the fields of d- and p-block metal–metal complexes that have developed extensively over the last fifty years. This perspective outlines the development of compounds, which possess polarised covalent or donor–acceptor f-element–metal bonds. For this review, the f-element is defined as (i) a group 3 or lanthanide metal: scandium, yttrium, lanthanum to lutetium, or (ii) an actinide metal: thorium, or uranium, and the metal is defined as a d-block transition metal, or a group 13 (aluminium or gallium), a group 14 (silicon, germanium, or tin), or a group 15 (antimony, or bismuth) metal. Silicon, germanium, and antimony are traditionally classified as metalloids but they are included for completeness. This review focuses mainly on complexes that have been structurally authenticated by single-crystal X-ray diffraction studies and we highlight novel aspects of their syntheses, properties, and reactivities.
![Silanamine,N,N'-[methylenebis(diphenylphosphoranylidyne)]bis[1,1,1-trimethyl-,ion(1-), potassium](/data/chemimg/1811300/373387-05-4.png)
![Silanamine,N,N'-[methylenebis(diphenylphosphoranylidyne)]bis[1,1,1-trimethyl-,ion(1-), potassium](/data/chemimg/1811300/373387-05-4_b.png)
![Heptaphosphatricyclo[2.2.1.02,6]heptane, tris(trimethylsilyl)-](http://img.cochemist.com/ccimg/58000/57990-97-3.png)
![Heptaphosphatricyclo[2.2.1.02,6]heptane, tris(trimethylsilyl)-](http://img.cochemist.com/ccimg/58000/57990-97-3_b.png)
![2H-Imidazol-2-ylidene, 1-[2-[(1,1-dimethylethyl)amino]ethyl]-3-methyl-](http://img.cochemist.com/ccimg/852700/852677-07-7.png)
![2H-Imidazol-2-ylidene, 1-[2-[(1,1-dimethylethyl)amino]ethyl]-3-methyl-](http://img.cochemist.com/ccimg/852700/852677-07-7_b.png)
![2(5H)-Furanone, 3,4-bis[(trimethylsilyl)oxy]-](http://img.cochemist.com/ccimg/478700/478618-90-5.png)
![2(5H)-Furanone, 3,4-bis[(trimethylsilyl)oxy]-](http://img.cochemist.com/ccimg/478700/478618-90-5_b.png)
![[(U(N(CH2CH2NSiMe3)3))2(μ-O)]](http://img.cochemist.com/ccimg/1333300/1333241-14-7.png)
![[(U(N(CH2CH2NSiMe3)3))2(μ-O)]](http://img.cochemist.com/ccimg/1333300/1333241-14-7_b.png)
![[U(N(CH2CH2NSiMe3)3)(THF)2][BPh4]](http://img.cochemist.com/ccimg/1333300/1333241-09-0.png)
![[U(N(CH2CH2NSiMe3)3)(THF)2][BPh4]](http://img.cochemist.com/ccimg/1333300/1333241-09-0_b.png)
![Tricyclo[3.3.1.13,7]decane, 1-azido-](/data/chemimg/409500/24886-73-5.png)
![Tricyclo[3.3.1.13,7]decane, 1-azido-](/data/chemimg/409500/24886-73-5_b.png)
![Methanone, [2-(hydroxydiphenylmethyl)phenyl]phenyl-](http://img.cochemist.com/ccimg/62800/62761-89-1.png)
![Methanone, [2-(hydroxydiphenylmethyl)phenyl]phenyl-](http://img.cochemist.com/ccimg/62800/62761-89-1_b.png)
![Potassium, [(trimethylsilyl)methyl]-](http://img.cochemist.com/ccimg/53200/53127-82-5.png)
![Potassium, [(trimethylsilyl)methyl]-](http://img.cochemist.com/ccimg/53200/53127-82-5_b.png)
![[1,2-Bis(diphenyphosphino)ethane]dichloroiron(II)](http://img.cochemist.com/ccimg/41600/41536-18-9.png)
![[1,2-Bis(diphenyphosphino)ethane]dichloroiron(II)](http://img.cochemist.com/ccimg/41600/41536-18-9_b.png)
![Potassium, [1-(trimethylsilyl)-2,4-cyclopentadien-1-yl]-](http://img.cochemist.com/ccimg/101700/101630-43-7.png)
![Potassium, [1-(trimethylsilyl)-2,4-cyclopentadien-1-yl]-](http://img.cochemist.com/ccimg/101700/101630-43-7_b.png)
![4,7,13,16,21,24-Hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane](http://img.cochemist.com/ccimg/24000/23978-09-8.png)
![4,7,13,16,21,24-Hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane](http://img.cochemist.com/ccimg/24000/23978-09-8_b.png)
![Potassium, [bis(diphenylphosphino)methyl]-](http://img.cochemist.com/ccimg/103900/103835-33-2.png)
![Potassium, [bis(diphenylphosphino)methyl]-](http://img.cochemist.com/ccimg/103900/103835-33-2_b.png)
