Co-reporter:S. J. Lancaster
Applied Organometallic Chemistry 2014 Volume 28( Issue 10) pp:
Publication Date(Web):
DOI:10.1002/aoc.3197
Co-reporter:Elizabeth A. Jacobs, Renukadevi Chandrasekar, Dan A. Smith, Callum M. White, Manfred Bochmann, Simon J. Lancaster
Journal of Organometallic Chemistry 2013 730() pp: 44-48
Publication Date(Web):
DOI:10.1016/j.jorganchem.2012.07.012
Co-reporter:Anna-Marie Fuller, David L. Hughes, Garth A. Jones and Simon J. Lancaster
Dalton Transactions 2012 vol. 41(Issue 18) pp:5599-5609
Publication Date(Web):10 Feb 2012
DOI:10.1039/C2DT00056C
Treatment of TiCl(NMe2)3 with H3N·B(C6F5)3 results in N–H activation and ligand exchange to yield the structurally characterised salt [TiCl(NMe2)2(NMe2H)2]+[TiNB(C6F5)3(Cl)2(NMe2H)2]−. Cation exchange with [Me4N]Cl, [Ph4P]Cl and [(PhCH2)Ph3P]Cl yields the respective ammonium and phosphonium salts of the [TiNB(C6F5)3(Cl)2(NMe2H)2]− anion. X-ray crystallography reveals that the essential trigonal bipyramidal geometry and composition of the anion is retained in each of these salts despite some minor variations in the Ti–N–B angle and the nature of the interionic interactions. Electronic investigation by DFT calculations confirmed the Ti–N triple bond character implied by the experimentally determined bond length, with the HOMO and HOMO-1 having Ti–N π-bonding character. The dimethylamine ligands of the anion resist substitution by moderate bases but can be displaced by pyridine to give a pentacoordinate anion. In contrast, addition of 2,2′-bipyridyl gives a neutral octahedral complex. Treatment of the pyridine complex with TlCp results in the formation of a four coordinate anionic cyclopentadienyl complex.
Co-reporter:Elizabeth A. Jacobs;Anna Fuller;Simon J. Coles;Garth A. Jones;Graham J. Tizzard;Joseph A. Wright
Chemistry - A European Journal 2012 Volume 18( Issue 28) pp:8647-8658
Publication Date(Web):
DOI:10.1002/chem.201200704
Abstract
Treatment of Me2S⋅B(C6F5)nH3−n (n=1 or 2) with ammonia yields the corresponding adducts. H3N⋅B(C6F5)H2 dimerises in the solid state through NH⋅⋅⋅HB dihydrogen interactions. The adducts can be deprotonated to give lithium amidoboranes Li[NH2B(C6F5)nH3−n]. Reaction of the n=2 reagent with [Cp2ZrCl2] leads to disubstitution, but [Cp2Zr{NH2B(C6F5)2H}2] is in equilibrium with the product of β-hydride elimination [Cp2Zr(H){NH2B(C6F5)2H}], which proves to be the major isolated solid. The analogous reaction with [Cp2HfCl2] gives a mixture of [Cp2Hf{NH2B(C6F5)2H}2] and the NH activation product [Cp2Hf{NHB(C6F5)2H}]. [Cp2Zr{NH2B(C6F5)2H}2]⋅PhMe and [Cp2Hf{NH2B(C6F5)2H}2]⋅4(thf) exhibit β-B-agostic chelate bonding of one of the two amidoborane ligands in the solid state. The agostic hydride is invariably coordinated to the outside of the metallocene wedge. Exceptionally, [Cp2Hf{NH2B(C6F5)2H}2]⋅PhMe has a structure in which the two amidoborane ligands adopt an intermediate coordination mode, in which neither is definitively agostic. [Cp2Hf{NHB(C6F5)2H}] has a formally dianionic imidoborane ligand chelating through an agostic interaction, but the bond-length distribution suggests a contribution from a zwitterionic amidoborane resonance structure. Treatment of the zwitterions [Cp2MMe(μ-Me)B(C6F5)3] (M=Zr, Hf) with Li[NH2B(C6F5)nH3−n] (n=2) results in [Cp2MMe{NH2B(C6F5)2H}] complexes, for which the spectroscopic data, particularly 1J(B,H), again suggest β-B-agostic interactions. The reactions proceed similarly for the structurally encumbered [Cp′′2ZrMe(μ-Me)B(C6F5)3] precursor (Cp′′=1,3-C5H3(SiMe3)2, n=1 or 2) to give [Cp′′2ZrMe{NH2B(C6F5)nH3−n}], both of which have been structurally characterised and show chelating, agostic amidoborane coordination. In contrast, the analogous hafnium chemistry leads to the recovery of [Cp′′2HfMe2] and the formation of Li[HB(C6F5)3] through hydride abstraction.
Co-reporter:Elizabeth A. Jacobs, Anna-Marie Fuller, Simon J. Lancaster and Joseph A. Wright
Chemical Communications 2011 vol. 47(Issue 20) pp:5870-5872
Publication Date(Web):18 Apr 2011
DOI:10.1039/C1CC11320H
Treatment of Cp2HfCl2 with two equivalents of LiNH2BH(C6F5)2 in toluene solution yields Cp2Hf{NHBH(C6F5)2}, which has been crystallographically characterised. The otherwise base-free [NHBH(C6F5)2] complex is stabilised by an agostic interaction.
Co-reporter:Anna-Marie Fuller, David L. Hughes and Simon J. Lancaster
Dalton Transactions 2011 vol. 40(Issue 28) pp:7434-7441
Publication Date(Web):20 Jun 2011
DOI:10.1039/C1DT10709G
Treatment of the tris(pyrazolyl)borate metal triamides Tp′M(NMe2)3, where Tp′ = (C3H3N2)3BH (Tp) or (3,5-Me2C3HN2)3BH (Tp*) and M = Ti, Zr and Hf, with the Brønsted acidic Lewis adduct (C6F5)3B·NH3 in toluene solution leads to the formation of Tp′M(NMe2)2{NH2B(C6F5)3} complexes. The exception to this was the attempted preparation of Tp*Ti(NMe2)2{NH2B(C6F5)3} which was unsuccessful. Where Tp′ = Tp and M = Ti and Zr and where Tp′ = Tp* and M = Zr the complexes have been characterized by single crystal X-ray diffraction methods, revealing the first examples of octahedral amidoborane complexes of the group 4 metals. Attempts to drive the reactions to completion resulted in competing preferential hydrolysis of the amidoborane group, regenerating (C6F5)3B·NH3.
Co-reporter:Anna-Marie Fuller, David L. Hughes, George E. Kostakis, Simon J. Lancaster, Annie K. Powell
Inorganica Chimica Acta 2011 Volume 366(Issue 1) pp:380-383
Publication Date(Web):30 January 2011
DOI:10.1016/j.ica.2010.10.022
Treatment of the ammonia adduct of tris(pentafluorophenyl)borane with 1.5 equivalents of pyrimidine affords a crystalline supramolecular complex. The solid state structure of the chloroform solvate has been determined by X-ray crystallography and is composed of two interpenetrating chiral (10,3)-a (srs) nets assembled through N–H⋯N hydrogen bonding interactions.Graphical abstractTreatment of the ammonia adduct of tris(pentafluorophenyl)borane with 1.5 equivalents of pyrimidine affords a crystalline supramolecular complex. The solid state structure of the chloroform solvate has been determined by X-ray crystallography and is composed of two interpenetrating chiral (10,3)-a (srs) nets assembled through N–H⋯N hydrogen bonding interactions.Research highlights► Tris(pentafluorophenyl)borane and pyrimidine form a hydrogen bonded network. ► Network consists of two interpenetrating chiral (10,3)-a (srs) nets. ► Supramolecular architecture is largely independent of solvent.
Co-reporter:Eddy Martin, David L. Hughes, Simon J. Lancaster
Inorganica Chimica Acta 2010 Volume 363(Issue 1) pp:275-278
Publication Date(Web):4 January 2010
DOI:10.1016/j.ica.2009.09.013
Treatment of LiC6F5 with B(C6F5)3 in equal volumes of light petroleum and diethyl ether at low temperature followed by slow warming to room temperature precipitates a microcrystalline solid which dries under vacuum to a material with the composition [Li(OEt2)3][B(C6F5)4]. Crystallization from diethyl ether yields solvent dependent [Li(OEt2)4][B(C6F5)4], which has been crystallographically characterised.Treatment of LiC6F5 with B(C6F5)3 in light petroleum and diethyl ether at low temperature followed by crystallization yields solvent dependent [Li(OEt2)4][B(C6F5)4] which is readily converted to a material with the composition [Li(OEt2)3][B(C6F5)4].
Co-reporter:Eddy Martin, William Clegg, Ross W. Harrington, David L. Hughes, Michael B. Hursthouse, Louise Male, Simon J. Lancaster
Polyhedron 2010 29(1) pp: 405-413
Publication Date(Web):
DOI:10.1016/j.poly.2009.06.018
Co-reporter:Anna-Marie Fuller, David L. Hughes, Simon J. Lancaster and Callum M. White
Organometallics 2010 Volume 29(Issue 9) pp:2194-2197
Publication Date(Web):April 14, 2010
DOI:10.1021/om100152v
The borane dimethyl sulfide adduct H3B·SMe2 and the diethyl ether adduct of tris(pentafluorophenyl)borane, (C6F5)3B·OEt2, undergo facile exchange of hydride and pentafluorophenyl ligands, yielding (C6F5)2HB·SMe2 (1) and (C6F5)H2B·SMe2 (2) depending upon the ratio of reagents used. In the presence of excess dimethyl sulfide, both compounds can be isolated as colorless crystals, which have been structurally characterized.
Co-reporter:Anna-Marie Fuller ; Andrew J. Mountford ; Matthew L. Scott ; Simon J. Coles ; Peter N. Horton ; David L. Hughes ; Michael B. Hursthouse
Inorganic Chemistry 2009 Volume 48(Issue 23) pp:11474-11482
Publication Date(Web):October 28, 2009
DOI:10.1021/ic901799q
The phosphinoborane adduct H3P·B(C6F5)3 can be deprotonated using LiN(SiMe3)2 to give the phosphidoborate salt Li[H2PB(C6F5)3], which was converted to the phosphidodiborates Li[H2P{B(C6F5)3}2] and Li[H2P{B(C6F5)3}{BH3}] by treatment with an equivalent of B(C6F5)3 or Me2S·BH3, respectively. A series of anions of the form [RR′P{M(C6F5)3}{BH3}]−, where R = R′ = Ph or R= tBu, R′ = H, and M = B or Al, were prepared (through treatment of salts Li[RR′P(BH3)] with the corresponding Lewis acid) and characterized using multinuclear NMR, elemental analysis and X-ray crystallography. The solid state structures of [Li(Et2O)x][Ph2P{M(C6F5)3}{BH3}] exhibit η2-bonding of the BH3 group to the cationic lithium center. The attempted preparation of an analogous series with amide cores of the form [R2N{B(C6F5)3}{BH3}]− proved unsuccessful; among the competing reaction pathways hydride abstraction occurred preferentially to yield Li[HB(C6F5)3] and dimers or higher oligomers with the composition (R2NBH2)n.
Co-reporter:Eddy Martin, David L. Hughes, Michael B. Hursthouse, Louise Male and Simon J. Lancaster
Dalton Transactions 2009 (Issue 9) pp:1593-1601
Publication Date(Web):19 Jan 2009
DOI:10.1039/B817252H
The Grignard reagent ArF′MgBr (ArF′ = 4-(C6F5)C6F4) reacts with Me3SiCl, Me2SiCl2 and Me3SnCl to give the 4-nonafluorobiphenyl group 14 complexes ArF′Me3Si, (ArF′)2Me2Si and ArF′Me3Sn respectively. ArF′Me3Sn undergoes only methyl group exchange when treated with BBr3, yielding ArF′Me2SnBr. The solid state structures of ArF′Me3Sn and ArF′Me2SnBr have been determined and exhibit the expected distorted tetrahedral geometries at tin. The reaction between three equivalents of ArF′MgBr and BF3 was not selective, while one equivalent of ArF′MgBr and (ArF)2BF (ArF = C6F5) reacted cleanly to give (ArF)2ArF′B. Treatment of BCl3 with three equivalents of ArF′Li, prepared at low temperature from the reaction between ArF′Br and n-BuLi, yielded (ArF′)3B. The molecular structures of the acetonitrile adducts of (ArF)2ArF′B and (ArF′)3B closely resemble that of (ArF)3B·NCMe. During the course of the boron investigations, reaction with adventitious water led to the structural characterization of (ArF′)2BOH·OH2 as a hydrogen-bonded dimer. The Grignard reagent reacts selectively with ZnCl2 in diethyl ether giving first [(ArF′)Zn(μ-Cl)(OEt2)]2 then (ArF′)2Zn(OEt2)2, both of which have been characterised by X-ray diffraction. The corresponding reaction with HgCl2 requires the use of tetrahydrofuran as the solvent and yields (ArF′)2Hg(THF)2.
Co-reporter:Anna-Marie Fuller, William Clegg, Ross W. Harrington, David L. Hughes and Simon J. Lancaster
Chemical Communications 2008 (Issue 44) pp:5776-5778
Publication Date(Web):08 Oct 2008
DOI:10.1039/B812785A
The crystalline ion-pair [TiCl(NMe2)2(NMe2H)2]+[TiCl2{NB(C6F5)3}(NMe2H)2]−, in which the anion has a triply bonded nitridoborate ligand, is formed through the multiple activation of H3N·B(C6F5)3 when treated with [Ti(NMe2)3Cl].
Co-reporter:Anna-Marie Fuller, Andrew J. Mountford, Simon J. Coles, Peter N. Horton, David L. Hughes, Michael B. Hursthouse, Louise Male and Simon J. Lancaster
Dalton Transactions 2008 (Issue 45) pp:6381-6392
Publication Date(Web):30 Sep 2008
DOI:10.1039/B808208A
The ammonia adduct of tris(pentafluorophenyl)boron, (C6F5)3B·NH3, is a potentially tri-functional hydrogen-bond donor. Co-crystallisation with the bases acetonitrile, pyridine, tetrahydrofuran, tetramethylethylenediamine, 15-crown-5, 1,4-diazabicyclo[2.2.2]octane (DABCO), pyrazine and 4,4′-bipyridine results, not in donor exchange, but in the formation of supermolecules assembled through hydrogen bonding to second coordination sphere acceptors. The complexes have been characterised by elemental analysis, multinuclear NMR and single-crystal diffraction methods. The solid-state architectures range in complexity, from the hydrogen bonded pairing of (C6F5)3B·NH3, with a single monodentate acceptor molecule (e.g.MeCN to form (C6F5)3B·NH3·NCMe), through complexation with all three N–H groups to the macrocycle 15-crown-5, to the formation of infinite one-dimensional chains with pyrazine and DABCO, and to two-dimensional networks with the divergent acceptor 4,4′-bipyridine.
Co-reporter:Eddy Martin, Claire Spendley, Andrew J. Mountford, Simon J. Coles, Peter N. Horton, David L. Hughes, Michael B. Hursthouse and Simon J. Lancaster
Organometallics 2008 Volume 27(Issue 7) pp:1436-1446
Publication Date(Web):March 5, 2008
DOI:10.1021/om701127p
Treatment of (C6F5)2Zn(toluene) with 2 equiv of a series of benzonitrile or pyridine derivatives yielded the complexes (C6F5)2Zn(L)2 (where L = benzonitrile, 4-(phenyl)benzonitrile, 4-(N-pyrrolyl)benzonitrile, pyridine, 4-(phenyl)pyridine, and 4-(N-pyrrolyl)pyridine). The four-coordinate solution-phase nature of these complexes was confirmed by a series of variable-temperature 19F NMR experiments and comparison to (C6F5)2Zn(2,2′-bipy). The solvent-free solid-state structures of each of the four-coordinate adducts and the toluene solvate of (C6F5)2Zn(NCC6H4C6H5)2 were determined by single-crystal X-ray diffraction and have distorted tetrahedral geometries. Analysis of the crystal packing revealed a preponderance of offset face-to-face homo−aryl and embrace-like interactions over the hetero−aryl, pentafluorophenyl−phenyl, interaction. These aryl−aryl synthons serve to assemble paired, one- and three-dimensional supramolecular architectures.
Co-reporter:Andrew J. Mountford Dr.;William Clegg ;Simon J. Coles Dr.;Ross W. Harrington Dr.;Peter N. Horton Dr.;Simon M. Humphrey Dr.;Michael B. Hursthouse ;Joseph A. Wright Dr.;Simon J. Lancaster Dr.
Chemistry - A European Journal 2007 Volume 13(Issue 16) pp:
Publication Date(Web):13 FEB 2007
DOI:10.1002/chem.200601751
Treatment of the homoleptic titanium amides [Ti(NR2)4] (R=Me or Et) with the Brønsted acidic reagent H3N⋅B(C6F5)3 results in the elimination of one molecule of amine and the formation of the four-coordinate amidoborate complexes [Ti(NR2)3{NH2B(C6F5)3}], the identity of which was confirmed by X-ray crystallography. The reaction with [Zr(NMe2)4] proceeds similarly but with retention of the amine ligand to give the trigonal-bipyramidal complex [Zr(NMe2)3{NH2B(C6F5)3}(NMe2H)]. Cyclopentadienyl (Cp) amidoborate complexes, [MCp(NR2)2{NH2B(C6F5)3}] (M=Ti, R=Me or Et; M=Zr, R=Me) can be prepared from [MCp(NR2)3] and H3N⋅B(C6F5)3, and exhibit greater thermal stability than the cyclopentadienyl-free compounds. H3N⋅B(C6F5)3 reacts with nBuLi or LiN(SiMe3)2 to give LiNH2B(C6F5)3, which complexes with strong Lewis acids to form ion pairs that contain weakly coordinating anions. The attempted synthesis of metallocene amidoborate complexes from dialkyl or diamide precursors and H3N⋅B(C6F5)3 was unsuccessful. However, LiNH2B(C6F5)3 does react with the highly electrophilic reagents [MCp2Me(μ-Me)B(C6F5)3] to give [MCp2Me(μ-NH2)B(C6F5)3] (M=Zr or Hf). Comparison of the molecular structures of the Group 4 amidoborate complexes reveals very similar BN, TiN and ZrN bond lengths, which are consistent with a description of the bonding as a dative interaction between an {M(L)n(NH2)} fragment and the Lewis acid B(C6F5)3. Each of the structures has an intramolecular hydrogen-bonding arrangement in which one of the nitrogen-bonded hydrogen atoms participates in a bifurcated F⋅⋅⋅H⋅⋅⋅F interaction to ortho-F atoms.
Co-reporter:Dale A. Pennington;Simon J. Coles;Michael B. Hursthouse;Manfred Bochmann
Macromolecular Rapid Communications 2006 Volume 27(Issue 8) pp:599-604
Publication Date(Web):18 APR 2006
DOI:10.1002/marc.200600006
Summary: Treatment of Zr{3-But-2-(O)C6H3CHN(C6F5)}Cl3(THF) with K[2-(C6H5NCH)C4H3N] yields Zr{3-But-2-(O)C6H3CHN(C6F5)}{2-(C6H5NCH)C4H3N}Cl2, the first example of a (salicylaldiminato)(pyrrolylaldiminato)zirconium complex. The catalytic behavior of both the new zirconium pre-catalyst and its titanium analogue have been determined. The titanium system is the more effective catalyst for both ethene homopolymerization and copolymerizations with hex-1-ene, norbornene, and cyclopentene. The titanium catalyst combines the high productivities of the bis(salicylaldiminato) parent complex with the more favorable comonomer incorporation of the bis(pyrrolylaldiminato) series.
Co-reporter:Eddy Martin;David L. Hughes
European Journal of Inorganic Chemistry 2006 Volume 2006(Issue 20) pp:
Publication Date(Web):12 SEP 2006
DOI:10.1002/ejic.200600671
Treatment of a toluene solution of Zn(C6F5)2 with p-C4H4N–C6H4CN yields (p-C4H4N–C6H4CN)2Zn(C6F5)2, which has been structurally characterised following recrystallization from 1,2-difluorobenzene by single-crystal X-ray diffraction and possesses the expected distorted tetrahedral molecular geometry. However, crystallization from dichloromethane yields a trigonal planar complex with only one p-C4H4N–C6H4CN ligand. The three-coordinate complex forms an intermolecular dimer in the solid state through a cooperative combination of zinc–arene, offset homoaromatic and dipole–dipole interactions.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Co-reporter:Dale A. Pennington, Simon J. Coles, Michael B. Hursthouse, Manfred Bochmann and Simon J. Lancaster
Chemical Communications 2005 (Issue 25) pp:3150-3152
Publication Date(Web):24 May 2005
DOI:10.1039/B504113A
The mono(salicylaldiminato) complexes Ti{3-tBu-2-(O)C6H3CHN(R)}Cl3(THF)
(where R = C6H5, C6F5) react with the metallated pyrrolylaldiminato ligand, K[2-(C6H5NCH)C4H3N], to afford the first examples of hybrid salicylaldiminato-ligated octahedral titanium complexes; the pre-catalysts give from very high to extremely high ethene polymerisation productivities when activated with MAO.
Co-reporter:Andrew J. Mountford, William Clegg, Ross W. Harrington, Simon M. Humphrey and Simon J. Lancaster
Chemical Communications 2005 (Issue 15) pp:2044-2046
Publication Date(Web):01 Mar 2005
DOI:10.1039/B500407A
Facile deprotonation of H3N·B(C6F5)3 with [M(NMe2)4]
(M = Zr or Ti) yields the novel amidoborate complexes [Zr(NMe2)3{NH2B(C6F5)3}(HNMe2)] and [Ti(NMe2)3{NH2B(C6F5)3}].
Co-reporter:Dale A. Pennington, William Clegg, Simon J. Coles, Ross W. Harrington, Michael B. Hursthouse, David L. Hughes, Mark E. Light, Mark Schormann, Manfred Bochmann and Simon J. Lancaster
Dalton Transactions 2005 (Issue 3) pp:561-571
Publication Date(Web):04 Jan 2005
DOI:10.1039/B414229B
The silyl ethers 3-But-2-(OSiMe3)C6H3CHNR (2a–e) have been prepared by deprotonation of the known iminophenols (1a–e) and treatment with SiClMe3
(a, R = C6H5; b, R = 2,6-Pri2C6H3; c, R = 2,4,6-Me3C6H2; d, R = 2-C6H5C6H4; e, R = C6F5). 2a–c react with TiCl4 in hydrocarbon solvents to give the binuclear complexes [Ti{3-But-2-(O)C6H3CHN(R)}Cl(µ-Cl3)TiCl3]
(3a–c). The pentafluorophenyl species 2e reacts with TiCl4 to give the known complex Ti{3-But-2-(O)C6H3CHN(R)}2Cl2. The mononuclear five-coordinate complex, Ti{3-But-2-(O)C6H3CHN(2,4,6-Me3C6H2)}Cl3
(4c), was isolated after repeated recrystallisation of 3c. Performing the dehalosilylation reaction in the presence of tetrahydrofuran yields the octahedral, mononuclear complexes Ti{3-But-2-(O)C6H3CHN(R)}Cl3(THF)
(5a–e). The reaction with ZrCl4(THF)2 proceeds similarly to give complexes Zr{3-But-2-(O)C6H3CHN(R)}Cl3(THF)
(6b–e). The crystal structures of 3b, 4c, 5a, 5c, 5e, 6b, 6d, 6e and the salicylaldehyde titanium complex Ti{3-But-2-(O)C6H3CHO}Cl3(THF)
(7) have been determined. Activation of complexes 5a–e and 6b–e with MAO in an ethene saturated toluene solution gives polyethylene with at best high activity depending on the imine substituent.
Co-reporter:Andrew J. Mountford, David L. Hughes and Simon J. Lancaster
Chemical Communications 2003 (Issue 17) pp:2148-2149
Publication Date(Web):15 Jul 2003
DOI:10.1039/B305613A
The reactions between the cyclic sec. amines pyrrolidine and piperidine with B(C6F5)3 yield Lewis acid-base adducts with both intra- and inter-molecular hydrogen bonding interactions between C–H and N–H groups and aryl-fluorines in the solid state.
Co-reporter:Simon J. Lancaster and David L. Hughes
Dalton Transactions 2003 (Issue 9) pp:1779-1789
Publication Date(Web):08 Apr 2003
DOI:10.1039/B300552F
Reaction of B(C5H4SiMe3)(C6F5)2 with MCl5
(M = Nb, Ta) leads to the first group 5 borylcyclopentadienyl half-sandwich complexes MCl4{C5H4B(C6F5)2}
(1 and 2). In contrast, the reaction with ZrCl4 gives the metallocene ZrCl2{C5H4B(C6F5)2}2
(3). The use of ZrCl4(SMe2)2 instead of ZrCl4 as starting material allows the isolation of the monocyclopentadienyl zirconium complex ZrCl3{C5H4B(C6F5)2(SMe2)}
(4). The utility of LiCp′ as a general route to zirconocenes is demonstrated by the synthesis of ZrCl2(Cp){C5H4B (C6F5)2(SMe2)}
(5) and ZrCl2(Ind){C5H4B(C6F5)2(SMe2)}
(6) (Ind =
η5-indenyl). Boron-substituted niobocenes are prepared through the dehalostannylation reaction between the half-sandwich complexes and tin-substituted cyclopentadienes. They adopt zwitterionic structures in which a chloride ligand is transferred to boron, for example Nb(+)Cl2(C5H4SiMe3){C5H4B(−)(Cl)(C6F5)2}
(9). The crystal structure of 9 has been determined by X-ray crystallography. Reaction of the strong base, pyridine, with the borylcyclopentadienyl complexes TiCl3{C5H4B(C6F5)2}, TiCl2(Cp){C5H4B(C6F5)2} and 1–6 leads to the generation of a series of pyridine adducts (10–17) in which the pyridine is bound to boron. The solid-state structures of the four coordinate adducts TiCl2(Cp){C5H4B(C6F5)2(py)}
(10) and TiCl3{C5H4B(C6F5)2(py)}
(14) are described. The half-sandwich zirconium and niobium complexes 15 and 16 are shown by spectroscopic and structural methods to coordinate a further one (Nb) or two (Zr) equivalents of pyridine to attain an octahedral geometry at the metal centre. The zwitterionic complexes 8 and 9 do not react with pyridine.
Co-reporter:Dale A. Pennington, David L. Hughes, Manfred Bochmann and Simon J. Lancaster
Dalton Transactions 2003 (Issue 18) pp:3480-3482
Publication Date(Web):18 Aug 2003
DOI:10.1039/B307793B
Reaction between 3-But-2-(OSiMe3)C6H3CHN(2,6-R2C6H3)
(where R = H (1a) or Pri
(1b)) and TiCl4(THF)2 affords the octahedral complexes Ti{3-But-2-(O)C6H3CHN(2,6-R2C6H3)}Cl3(THF) while in the absence of THF 1b reacts with TiCl4 to give the binuclear complex [Ti{3-But-2-(O)C6H3CHN(2,6-Pri2C6H3)}Cl(μ–Cl)3TiCl3]; the complexes give good productivities for ethene polymerisation when activated with MAO.
Co-reporter:Anna-Marie Fuller, David L. Hughes and Simon J. Lancaster
Dalton Transactions 2011 - vol. 40(Issue 28) pp:NaN7441-7441
Publication Date(Web):2011/06/20
DOI:10.1039/C1DT10709G
Treatment of the tris(pyrazolyl)borate metal triamides Tp′M(NMe2)3, where Tp′ = (C3H3N2)3BH (Tp) or (3,5-Me2C3HN2)3BH (Tp*) and M = Ti, Zr and Hf, with the Brønsted acidic Lewis adduct (C6F5)3B·NH3 in toluene solution leads to the formation of Tp′M(NMe2)2{NH2B(C6F5)3} complexes. The exception to this was the attempted preparation of Tp*Ti(NMe2)2{NH2B(C6F5)3} which was unsuccessful. Where Tp′ = Tp and M = Ti and Zr and where Tp′ = Tp* and M = Zr the complexes have been characterized by single crystal X-ray diffraction methods, revealing the first examples of octahedral amidoborane complexes of the group 4 metals. Attempts to drive the reactions to completion resulted in competing preferential hydrolysis of the amidoborane group, regenerating (C6F5)3B·NH3.
Co-reporter:Elizabeth A. Jacobs, Anna-Marie Fuller, Simon J. Lancaster and Joseph A. Wright
Chemical Communications 2011 - vol. 47(Issue 20) pp:NaN5872-5872
Publication Date(Web):2011/04/18
DOI:10.1039/C1CC11320H
Treatment of Cp2HfCl2 with two equivalents of LiNH2BH(C6F5)2 in toluene solution yields Cp2Hf{NHBH(C6F5)2}, which has been crystallographically characterised. The otherwise base-free [NHBH(C6F5)2] complex is stabilised by an agostic interaction.
Co-reporter:Anna-Marie Fuller, William Clegg, Ross W. Harrington, David L. Hughes and Simon J. Lancaster
Chemical Communications 2008(Issue 44) pp:NaN5778-5778
Publication Date(Web):2008/10/08
DOI:10.1039/B812785A
The crystalline ion-pair [TiCl(NMe2)2(NMe2H)2]+[TiCl2{NB(C6F5)3}(NMe2H)2]−, in which the anion has a triply bonded nitridoborate ligand, is formed through the multiple activation of H3N·B(C6F5)3 when treated with [Ti(NMe2)3Cl].
Co-reporter:Anna-Marie Fuller, David L. Hughes, Garth A. Jones and Simon J. Lancaster
Dalton Transactions 2012 - vol. 41(Issue 18) pp:NaN5609-5609
Publication Date(Web):2012/02/10
DOI:10.1039/C2DT00056C
Treatment of TiCl(NMe2)3 with H3N·B(C6F5)3 results in N–H activation and ligand exchange to yield the structurally characterised salt [TiCl(NMe2)2(NMe2H)2]+[TiNB(C6F5)3(Cl)2(NMe2H)2]−. Cation exchange with [Me4N]Cl, [Ph4P]Cl and [(PhCH2)Ph3P]Cl yields the respective ammonium and phosphonium salts of the [TiNB(C6F5)3(Cl)2(NMe2H)2]− anion. X-ray crystallography reveals that the essential trigonal bipyramidal geometry and composition of the anion is retained in each of these salts despite some minor variations in the Ti–N–B angle and the nature of the interionic interactions. Electronic investigation by DFT calculations confirmed the Ti–N triple bond character implied by the experimentally determined bond length, with the HOMO and HOMO-1 having Ti–N π-bonding character. The dimethylamine ligands of the anion resist substitution by moderate bases but can be displaced by pyridine to give a pentacoordinate anion. In contrast, addition of 2,2′-bipyridyl gives a neutral octahedral complex. Treatment of the pyridine complex with TlCp results in the formation of a four coordinate anionic cyclopentadienyl complex.
Co-reporter:Eddy Martin, David L. Hughes, Michael B. Hursthouse, Louise Male and Simon J. Lancaster
Dalton Transactions 2009(Issue 9) pp:NaN1601-1601
Publication Date(Web):2009/01/19
DOI:10.1039/B817252H
The Grignard reagent ArF′MgBr (ArF′ = 4-(C6F5)C6F4) reacts with Me3SiCl, Me2SiCl2 and Me3SnCl to give the 4-nonafluorobiphenyl group 14 complexes ArF′Me3Si, (ArF′)2Me2Si and ArF′Me3Sn respectively. ArF′Me3Sn undergoes only methyl group exchange when treated with BBr3, yielding ArF′Me2SnBr. The solid state structures of ArF′Me3Sn and ArF′Me2SnBr have been determined and exhibit the expected distorted tetrahedral geometries at tin. The reaction between three equivalents of ArF′MgBr and BF3 was not selective, while one equivalent of ArF′MgBr and (ArF)2BF (ArF = C6F5) reacted cleanly to give (ArF)2ArF′B. Treatment of BCl3 with three equivalents of ArF′Li, prepared at low temperature from the reaction between ArF′Br and n-BuLi, yielded (ArF′)3B. The molecular structures of the acetonitrile adducts of (ArF)2ArF′B and (ArF′)3B closely resemble that of (ArF)3B·NCMe. During the course of the boron investigations, reaction with adventitious water led to the structural characterization of (ArF′)2BOH·OH2 as a hydrogen-bonded dimer. The Grignard reagent reacts selectively with ZnCl2 in diethyl ether giving first [(ArF′)Zn(μ-Cl)(OEt2)]2 then (ArF′)2Zn(OEt2)2, both of which have been characterised by X-ray diffraction. The corresponding reaction with HgCl2 requires the use of tetrahydrofuran as the solvent and yields (ArF′)2Hg(THF)2.
Co-reporter:Anna-Marie Fuller, Andrew J. Mountford, Simon J. Coles, Peter N. Horton, David L. Hughes, Michael B. Hursthouse, Louise Male and Simon J. Lancaster
Dalton Transactions 2008(Issue 45) pp:NaN6392-6392
Publication Date(Web):2008/09/30
DOI:10.1039/B808208A
The ammonia adduct of tris(pentafluorophenyl)boron, (C6F5)3B·NH3, is a potentially tri-functional hydrogen-bond donor. Co-crystallisation with the bases acetonitrile, pyridine, tetrahydrofuran, tetramethylethylenediamine, 15-crown-5, 1,4-diazabicyclo[2.2.2]octane (DABCO), pyrazine and 4,4′-bipyridine results, not in donor exchange, but in the formation of supermolecules assembled through hydrogen bonding to second coordination sphere acceptors. The complexes have been characterised by elemental analysis, multinuclear NMR and single-crystal diffraction methods. The solid-state architectures range in complexity, from the hydrogen bonded pairing of (C6F5)3B·NH3, with a single monodentate acceptor molecule (e.g.MeCN to form (C6F5)3B·NH3·NCMe), through complexation with all three N–H groups to the macrocycle 15-crown-5, to the formation of infinite one-dimensional chains with pyrazine and DABCO, and to two-dimensional networks with the divergent acceptor 4,4′-bipyridine.
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