Co-reporter:Lei Zhang, Congcong Zhang, Guohua Hou, Guofu Zi, and Marc D. Walter
Organometallics March 27, 2017 Volume 36(Issue 6) pp:1179-1179
Publication Date(Web):March 10, 2017
DOI:10.1021/acs.organomet.7b00064
Addition of potassium graphite (KC8) to a solution of (η5-C5Me5)2UCl2 (1) and 2,2′-bipyridine (bipy) gives the uranium bipyridyl metallocene (η5-C5Me5)2U(bipy) (2) in good yield. In complex 2 a bipy radical anion is coordinated to a U(III) atom, and it is therefore an ideal starting material for small-molecule activation: e.g., it serves as a synthetic equivalent for the (η5-C5Me5)2UII fragment on treatment with conjugated alkynes and a variety of heterounsaturated molecules such as imines, carbodiimide, organic azides, hydrazine, and azo derivatives. Alternatively, it may also react with aldehydes, ketones, nitriles, and α,β-unsaturated reagents such as p-ClPhCHO, (CH2)5CO, PhCN, and methyl methacrylate (MMA), forming the C–C bond coupling products (η5-C5Me5)2U[(bipy)(p-ClPhCHO)] (10), (η5-C5Me5)2U[(bipy){(CH2)5CO}] (11), (η5-C5Me5)2U[(bipy)(PhCN)] (12), (η5-C5Me5)2U[(bipy){CH2═C(Me)CO(OMe)] (13a), and [(η5-C5Me5)2U{OC(OMe)═C(Me)CH2–3-bipy}]2 (13b), respectively, in quantitative conversion. Furthermore, addition of CuI to complex 2 induces a single-electron-transfer process to form the uranium(III) iodide complex (η5-C5Me5)2U(I)(bipy) (14).
Co-reporter:Lei Zhang, Bo Fang, Guohua HouGuofu Zi, Wanjian Ding, Marc D. Walter
Organometallics February 27, 2017 Volume 36(Issue 4) pp:
Publication Date(Web):February 8, 2017
DOI:10.1021/acs.organomet.6b00936
The synthesis, electronic structure, and reactivity of a uranium metallacyclocumulene were studied. Reduction of [(η5-C5Me5)2UCl2] (1) with potassium graphite (KC8) in the presence of 1,4-bis(trimethylsilyl)butadiyne (Me3SiC≡C–C≡CSiMe3) forms the uranium metallacyclocumulene [(η5-C5Me5)2U{η4-C4(SiMe3)2}] (2) in good yield. Magnetic susceptibility data confirm that 2 behaves as a U(IV) complex, and density functional theory (DFT) studies indicate a substantial 5f orbital contribution to the bonding of the metallacyclopentatriene U(η4-C═C═C═C) moiety, leading to more covalent bonds between the [(η5-C5Me5)2U]2+ and [η4-C4(SiMe3)2]2– fragments than those found in the related Th(IV) compound. Consequently, very different reactivity patterns emerge; e.g., 2 can act as a synthetic equivalent for the (η5-C5Me5)2U(II) fragment when reacted with conjugated species such as butadiyne, bipy, and diazabutadiene derivatives. Alternatively, the [(η4-Me3SiC═C═C═CSiMe3)]2– moiety in 2 may react as a nucleophile when exposed to a variety of simple heterounsaturated molecules such as aldehydes, ketones, nitriles, isothiocyanates, carbodiimides, pyridines, and organic azides. DFT studies are included to complement the experimental observations.
Co-reporter:Congcong Zhang, Pikun Yang, Enwei Zhou, Xuebin Deng, Guofu Zi, and Marc D. Walter
Organometallics December 11, 2017 Volume 36(Issue 23) pp:4525-4525
Publication Date(Web):May 10, 2017
DOI:10.1021/acs.organomet.7b00212
The Lewis base supported thorium terminal imido metallocene (η5-C5Me5)2Th═N(mesityl)(DMAP) (1) reacts with various small organic molecules such as thiazoles, silanes, internal acetylenes, nitriles, ketones, CS2, isothiocyanates, carbodiimides, lactides, organic azides, and diazoalkane derivatives. For example, while 1 forms the adduct (η5-C5Me5)2Th═N(mesityl)(OPPh3) (2) with Ph3PO, deprotonation occurs between 1 and thiazole to give the amido thiazolyl complex (η5-C5Me5)2Th(NHmesityl)(C3H2NS) (3). Moreover, the five-membered metallaheterocycle (η5-C5Me5)2Th[κ2-N,C-{N(2-CH2-4,6-Me2C6H2)(SiH2Ph)}](DMAP) (4) is isolated from a mixture of 1 and PhSiH3. In addition, treatment of 1 with PhCN, Ph2CHCN, or Me3SiCN gives the zwitterionic complex (η5-C5Me5)2Th[κ-N-{NCPh(N(mesityl))}](DMAP) (5), and iminato compounds (η5-C5Me5)2Th[N(mesityl)C(CHPh2)NH](N═C═CPh2) (6) and (η5-C5Me5)2Th[2-{N═C(SiMe3)}-4-Me2NC5H3N](NC) (7), respectively. Furthermore, reaction of 1 with PhC≡CMe and Me3SiC≡CC≡CSiMe3 afford the amido pyridyl complexes (η5-C5Me5)2Th[N(mesityl)C(Me)═CHPh](κ2-C,N-4-Me2NC5H3N) (8) and (η5-C5Me5)2Th[N(mesityl)C(C2SiMe3)═CHSiMe3](κ2-C,N-4-Me2NC5H3N) (9), respectively. Treatment of 1 with N,N′-diisopropylcarbodiimide furnishes the [2 + 2] cycloaddition product (η5-C5Me5)2Th[N(mesityl)C(═NiPr)-NiPr](DMAP) (10), whereas reaction of 1 with CS2 or PhNCS affords the four-membered metallaheterocycles (η5-C5Me5)2Th[SC═N(mesityl)-S](DMAP) (11) and (η5-C5Me5)2Th[SC═N(mesityl)-NPh](DMAP) (12), respectively. Moreover, while the four-membered metallaheterocycle (η5-C5Me5)2Th[(μ-O)2(CPh2)](DMAP) (13) is formed upon addition of Ph2CO to 1, deprotonation occurs between 1 and 1-indanone to give the amido enolyl compound (η5-C5Me5)2Th(NH(mesityl))(κ-O-1-OC9H7) (14). Nevertheless, the eight-membered metallaheterocycle (η5-C5Me5)2Th[OCH(Me)C(═O)OCH(Me)C(═N(mesityl))O] (15) is isolated from reaction of 1 with rac-lactide. Furthermore, while mixing 1 with (p-tolyl)N3 affords the tetraazametallacyclopentene (η5-C5Me5)2Th[N(p-tolyl)N═NN(p-tolyl)] (16), reaction of 1 with Me3SiCHN2 forms the bimetallic complex [(η5-C5Me5)2Th]2(μ-N═NN═CSiMe3)2 (17) concomitant with the elimination of mesitylene. The new complexes 2–15 and 17 were characterized by various spectroscopic techniques, including single-crystal X-ray diffraction studies.
Co-reporter:Lei Zhang;Guohua Hou;Wanjian Ding;Marc D. Walter
Dalton Transactions 2017 vol. 46(Issue 11) pp:3716-3728
Publication Date(Web):2017/03/14
DOI:10.1039/C7DT00396J
The uranium metallacyclocumulene, [η5-1,3-(Me3C)2C5H3]2U(η4-C4Ph2) (2) was isolated by the reduction of [η5-1,3-(Me3C)2C5H3]2UCl2 (1) with potassium graphite (KC8) in the presence of 1,4-diphenylbutadiyne (PhCC–CCPh) in good yield. Furthermore it was fully characterized including the determination of its molecular structure; and the reactivity of 2 towards various small unsaturated organic molecules was explored. For example, while complex 2 shows no reactivity with alkynes and 2,2′-bipyridine (bipy), it reacts as a nucleophile when exposed to carbodiimides, diazabutadienes, isothiocyanates, ketones, and pyridine derivatives, leading to five-, seven- or nine-membered heterometallacycles. In contrast, treatment of complex 2 with CS2 results in CS bond cleavage and forms the binuclear complex [η5-1,3-(Me3C)2C5H3]2U[μ-η4:η3-PhCCC(S)C(Ph)CS]U[η5-1,3-(Me3C)2C5H3]2 (10). Density functional theory (DFT) studies complement the experimental study.
Co-reporter:Lei Zhang; Guohua Hou; Guofu Zi; Wanjian Ding;Marc D. Walter
Journal of the American Chemical Society 2016 Volume 138(Issue 15) pp:5130-5142
Publication Date(Web):April 12, 2016
DOI:10.1021/jacs.6b01391
The synthesis, structure, and reactivity of a uranium metallacyclopropene were comprehensively studied. Reduction of (η5-C5Me5)2UCl2 (1) with potassium graphite (KC8) in the presence of bis(trimethylsilyl)acetylene (Me3SiC≡CSiMe3) allows the first stable uranium metallacyclopropene (η5-C5Me5)2U[η2-C2(SiMe3)2] (2) to be isolated. Magnetic susceptibility data confirm that 2 is a U(IV) complex, and density functional theory (DFT) studies indicate substantial 5f orbital contributions to the bonding of the metallacyclopropene U-(η2-C═C) moiety, leading to more covalent bonds between the (η5-C5Me5)2U2+ and [η2-C2(SiMe3)2]2– fragments than those in the related Th(IV) compound. Consequently, very different reactivity patterns emerge, e.g., 2 can act as a source for the (η5-C5Me5)2U(II) fragment when reacted with alkynes and a variety of heterounsaturated molecules such as imines, bipy, carbodiimide, organic azides, hydrazine, and azo derivatives.
Co-reporter:Pikun Yang, Enwei Zhou, Bo Fang, Guohua Hou, Guofu Zi, and Marc D. Walter
Organometallics 2016 Volume 35(Issue 12) pp:2129-2139
Publication Date(Web):June 7, 2016
DOI:10.1021/acs.organomet.6b00357
Reduction of (η5-C5Me5)2ThCl2 (1) with potassium graphite (KC8) in the presence of 2,2′-bipyridine forms the thorium bipy metallocene (η5-C5Me5)2Th(bipy) (2) in good yield. Complex 2 was fully characterized and reacts with various small molecules. For example, 2 serves as a source for the (η5-C5Me5)2Th(II) fragment when exposed to conjugated alkynes, elemental sulfur and their organic derivatives, diazabutadiene, carbodiimide, CS2, isothiocyanate, and organic azides. Furthermore, treatment of 2 with ketone Ph2CO, thio-ketone Ph2CS, imine PhCH═NPh, and nitrile PhCN results in C–C bond coupling products (η5-C5Me5)2Th[(bipy)(Ph2CO)] (10), (η5-C5Me5)2Th[(bipy)(Ph2CS)] (11), (η5-C5Me5)2Th[(bipy)(PhCHNPh)] (12), and (η5-C5Me5)2Th[(bipy)(PhCN)] (13), respectively, in quantitative conversion.
Co-reporter:Bo Fang, Guohua Hou, Guofu Zi, Wanjian Ding, and Marc D. Walter
Organometallics 2016 Volume 35(Issue 10) pp:1384-1391
Publication Date(Web):January 4, 2016
DOI:10.1021/acs.organomet.5b00945
The formation of thorium metallacyclopentadiene and metallacyclopropene complexes is significantly influenced by the steric and electronic properties of the internal alkyne employed during their syntheses. The reduction of (η5-C5Me5)2ThCl2 (2) with potassium graphite (KC8) or lithium in the presence of internal phenyl(alkyl)acetylenes (PhC≡CR) selectively yields the corresponding Cs-symmetric thorium metallacyclopentadienes (η5-C5Me5)2Th[η2-C(Ph)═C(R)C(Ph)═C(R)] (R = Me (4), iPr (5), C6H11 (6)), while the phenyl(silyl)acetylene PhC≡CSiHMe2 gives the C2v-symmetric metallacyclopentadiene (η5-C5Me5)2Th[η2-C(SiHMe2)═C(Ph)C(Ph)═C(SiHMe2)] (7). However, the sterically more encumbered acetylene derivative PhC≡CSiMe3 affords the chloro metallacyclopropene complex [(η5-C5Me5)2Th(η2-C2Ph(SiMe3))(Cl)][Li(EDM)2] (8), whereas Me3SiC≡CSiMe3 forms the chloro alkenyl complex [(η5-C5Me5)2Th[C(SiMe3)═CHSiMe3](Cl) (9), in which the chloro metallacyclopropene intermolecularly activates a C–H bond of the solvent (C7H8). Density functional theory (DFT) studies complement the experimental findings and rationalize the selectivity observed in the C–C bond formation.
Co-reporter:Dao Zhang and Guofu Zi
Chemical Society Reviews 2015 vol. 44(Issue 7) pp:1898-1921
Publication Date(Web):22 Jan 2015
DOI:10.1039/C4CS00441H
Since the discovery of a stable N-heterocyclic carbene (NHC), the use of NHCs in chemistry has developed rapidly over the past two decades. These interesting compounds are predominantly employed in organometallic chemistry as ligands for various metal centers, and as organocatalysts for a variety of transformations. In particular, the NHC transition metal complexes have received widespread attention, and significant progress has been made in the development of group 4 NHC-complexes in the last few years. These group 4 NHC-complexes are of interest because of their unique structural properties, and their potential application in organic transformations and catalysis. This review covers the superior design strategies for NHC ligands to stabilize early transition metals and well-defined group 4 metal complexes with mono- and multi-dentate NHC ligands. In this context, four types of NHC-complexes, i.e., carbon-functionalized NHCs, nitrogen-functionalized NHCs, oxygen-functionalized NHCs and nitrogen/oxygen-functionalized unsymmetric NHCs, are described. In addition, the use of group 4 NHC-complexes as catalysts in olefin (co)polymerization, ring-opening polymerization of rac-lactide, copolymerization of epoxides and CO2, as well as hydroamination/cyclization of aminoalkenes, is presented. Furthermore, limitations and challenges are discussed.
Co-reporter:Ann Christin Fecker, Matthias Freytag, Peter G. Jones, Ning Zhao, Guofu Zi and Marc D. Walter
Dalton Transactions 2015 vol. 44(Issue 37) pp:16325-16331
Publication Date(Web):24 Aug 2015
DOI:10.1039/C5DT02851E
The synthesis of C2 symmetric enantiomerically pure open Ca and Sr metallocenes, [(η5-pdl*)2Ca(thf)] (1) and [(η5-pdl*)2Sr(thf)2] (2) (pdl* = dimethylnopadienyl) is described and these complexes were fully characterized. The solid state structures confirm that the pdl* ligands coordinate exclusively with the less sterically demanding site to the Ca and Sr atoms. These complexes are active catalysts for the controlled ring opening polymerization (ROP) of rac-lactide to give heterotactically enriched polylactides (PL) with narrow polydispersities (PDI = 1.29–1.31) and without adding further activators.
Co-reporter:Enwei Zhou, Wenshan Ren, Guohua Hou, Guofu Zi, De-Cai Fang, and Marc D. Walter
Organometallics 2015 Volume 34(Issue 14) pp:3637-3647
Publication Date(Web):July 2, 2015
DOI:10.1021/acs.organomet.5b00454
The base-free thorium terminal imido [η5-1,2,4-(Me3C)3C5H2]2Th═N(p-tolyl) (1) activates a variety of small molecules such as pyridine derivatives, amines, boranes, chlorosilane, elemental selenium, and α,β-unsaturated esters. Reaction of 1 with pyridine, pyridine N-oxide, 2-methylpyridine N-oxide, p-toluidine, Ph2NH, 9-borabicyclo[3.3.1]nonane (9-BBN), PhSiH2Cl, elemental selenium, PhSeSePh, and methyl methacrylate (MMA) formed the amido pyridyl complexes [η5-1,2,4-(Me3C)3C5H2]2Th(NH-p-tolyl)(η2-C,N-C5H4N) (2), [η5-1,2,4-(Me3C)3C5H2]2Th(NH-p-tolyl)(κ2-C,O-C5H4NO) (3), and [η5-1,2,4-(Me3C)3C5H2]2Th(NH-p-tolyl)(κ2-C,O-2-MeC5H3NO) (4), diamide complexes [η5-1,2,4-(Me3C)3C5H2]2Th(NH-p-tolyl)2 (5) and [η5-1,2,4-(Me3C)3C5H2]2Th(NH-p-tolyl)(NPh2) (6), amido hydrido complex [η5-1,2,4-(Me3C)3C5H2]2Th(H)[N(p-tolyl)B(C8H14)] (7), amido chloride complex [η5-1,2,4-(Me3C)3C5H2]2Th(Cl)[N(p-tolyl)SiH2Ph] (8), amido selenido complexes [η5-1,2,4-(Me3C)3C5H2]2Th[N(p-tolyl)Se–Se] (9) and {[η5-1,2,4-(Me3C)3C5H2]Th(SePh)}2[μ-N(p-tolyl)]2 (10), and amido enolyl complex [η5-1,2,4-(Me3C)3C5H2]2Th[N(p-tolyl)CH2C(Me)═C(OMe)O] (11). The new complexes 2–3 and 6–11 were characterized by various spectroscopic techniques including single crystal X-ray diffraction. Furthermore, density functional theory (DFT) studies complement the experimental investigations.
Co-reporter:Bo Fang, Lei Zhang, Guohua Hou, Guofu Zi, De-Cai Fang, and Marc D. Walter
Organometallics 2015 Volume 34(Issue 23) pp:5669-5681
Publication Date(Web):November 19, 2015
DOI:10.1021/acs.organomet.5b00923
Reduction of (η5-C5Me5)2ThCl2 (1) with potassium graphite (KC8) in the presence of 1,4-diphenylbutadiyne (PhC≡CC≡CPh) yields the first actinide metallacyclocumulene, the thorium metallacyclopentatriene (η5-C5Me5)2Th(η4-C4Ph2) (2). The structure and reactivity of 2 were investigated in detail; structural parameters and density functional theory (DFT) studies confirm the presence of a metallacyclopentatriene unit in 2. Furthermore, DFT computations also indicate a notable contribution of the 5f orbitals to the bonding of the metallacyclopentatriene Th–(η4-C═C═C═C) moiety. While complex 2 shows no reactivity toward alkynes, it reacts with a variety of heterounsaturated molecules such as isothiocyanates, carbodiimides, aldehydes, ketones, nitriles, pyridines, and diazoalkane derivatives. DFT studies complement the experimental observations and provide additional insights. Furthermore, in comparison to group 4 metals, the thorium metallacyclopentatriene 2 exhibits distinctively different reactivity patterns.
Co-reporter:Bo Fang ; Wenshan Ren ; Guohua Hou ; Guofu Zi ; De-Cai Fang ; Laurent Maron ;Marc D. Walter
Journal of the American Chemical Society 2014 Volume 136(Issue 49) pp:17249-17261
Publication Date(Web):December 2, 2014
DOI:10.1021/ja509770t
The synthesis, structure, and reactivity of an actinide metallacyclopropene were comprehensively studied. The reduction of [η5-1,2,4-(Me3C)3C5H2]2ThCl2 (1) with potassium graphite (KC8) in the presence of diphenylacetylene (PhC≡CPh) yields the first stable actinide metallacyclopropene [η5-1,2,4-(Me3C)3C5H2]2Th(η2-C2Ph2) (2). The magnetic susceptibility data show that 2 is indeed a diamagnetic Th(IV) complex, and density functional theory (DFT) studies suggest that the 5f orbitals contribute to the bonding of the metallacyclopropene Th—(η2-C═C) moiety. Complex 2 shows no reactivity toward alkynes, but it reacts with a variety of heterounsaturated molecules such as aldehyde, ketone, carbodiimide, nitrile, organic azide, and diazoalkane derivatives. DFT studies complement the experimental observations and provide additional insights. Furthermore, a comparison between Th and group 4 metals reveals that Th4+ shows unique reactivity patterns.
Co-reporter:Ning Zhao, Guohua Hou, Xuebin Deng, Guofu Zi and Marc D. Walter
Dalton Transactions 2014 vol. 43(Issue 22) pp:8261-8272
Publication Date(Web):07 Mar 2014
DOI:10.1039/C4DT00510D
Chiral group 4 NHC–metal complexes were prepared in good yields by amine elimination from M(NR2)4 (M = Ti, Zr, Hf; R = Me, Et) and chiral pincer NHC-ligands, L4 (L4a and L4b), L5 and L6, which are derived from (S,S)-diphenyl-1,2-ethanediamine. Treatment of M(NR2)4 with 1 equiv. of L4 in THF gives, after recrystallization from a benzene solution, the chiral titanium amides (L4)Ti(NMe2)(Br)(THF) (7) and (L4)Ti(NMe2)(Cl)(THF) (11), zirconium amides (L4)Zr(NMe2)(Br)(THF) (8), (L4)Zr(NEt2)(Br)(THF) (10), (L4)Zr(NMe2)(Cl)(THF) (12) and (L4)Zr(NEt2)(Cl)(THF) (14), and hafnium amides (L4)Hf(NMe2)(Br)(THF) (9) and (L4)Hf(NMe2)(Cl)(THF) (13), respectively. Similarly, the reactions of L5 or L6 with 1 equiv. of M(NR2)4 yield the titanium amide (L6)Ti(NMe2)(Cl)(THF) (16), the zirconium amides (L5)Zr(NMe2)(Cl)(THF) (15), (L6)Zr(NMe2)(Cl)(THF) (17) and (L6)Zr(NEt2)(Cl)(THF) (19), and the hafnium amide (L6)Hf(NMe2)(Cl)(THF) (18), respectively. Complexes 7–19 were characterized by various spectroscopic techniques and elemental analyses. The molecular structures of 10 and 14–19 were also established by X-ray diffraction analyses, which represent the first example of the structurally characterized group 4 chiral NHC–metal complex. Furthermore, 7–19 are active catalysts for the polymerization of rac-lactide in the presence of isopropanol, leading to the heterotactic-rich polylactides.
Co-reporter:Wenshan Ren, Liang Chen, Ning Zhao, Qiuwen Wang, Guohua Hou, Guofu Zi
Journal of Organometallic Chemistry 2014 Volume 758() pp:65-72
Publication Date(Web):15 May 2014
DOI:10.1016/j.jorganchem.2014.02.005
•A new series of chiral organolanthanide complexes have been reported.•Solvent has effect on the formation of the organolanthanide complexes.•They are active catalysts for the polymerization of rac-lactide.A new series of organolanthanide complexes have been prepared by silylamine elimination in good yields from Ln[N(SiMe3)2]3 and chiral biaryl Schiff-base NO2 ligands, 1H2–4H2, which are derived from (S)-2-amino-2′-hydroxy-1,1′-binaphthyl or (S)-2-amino-2′-hydroxy-6,6′-dimethyl-1,1′-biphenyl, respectively. However, the formation of the organolanthanide complexes is strongly influenced by the solvent used in the synthesis. For example, treatment of ligand 1H2 or 2H2 with 1 equiv of Ln[N(SiMe3)2]3 in DME or THF gives the mononuclear complexes (1)Ln[N(SiMe3)2](DME) (Sm (5), Y (6), Yb (7)) and (2)Y[N(SiMe3)2](THF)2 (8), respectively. While reaction of 2H2, 3H2 or 4H2 with 1 equiv of Ln[N(SiMe3)2]3 in toluene gives the binuclear complexes {(2)Ln[N(SiMe3)2]}2 (Ln = Sm (9), Yb (10)), {(3)Yb[N(SiMe3)2]}2 (11) and {(4)Ln[N(SiMe3)2]}2 (Ln = Y (12), Yb (13)), respectively. Complexes 5–13 have been characterized by various spectroscopic techniques, elemental analyses, and X-ray diffraction analyses. The complexes 5–13 are active catalysts for the polymerization of rac-lactide, leading to the isotactic-rich polylactides.A new series of organolanthanide complexes have been prepared from chiral biaryl Schiff-base NO2 ligands. The organolanthanide complexes are active catalysts for the polymerization of rac-lactide, leading to the isotactic-rich polylactides.
Co-reporter:Ning Zhao, Qiuwen Wang, Guohua Hou, Haibin Song, Guofu Zi
Journal of Organometallic Chemistry 2014 Volume 754() pp:51-58
Publication Date(Web):15 March 2014
DOI:10.1016/j.jorganchem.2013.12.035
•Six new chiral binuclear aluminum complexes have been reported.•The steric effect of the ligand plays an important role in the complex formation.•The aluminum complexes are active catalysts for the polymerization of rac-lactide.Six new binuclear organoaluminum complexes (1)2Al2Me2 (7), {(2)AlMe}2 (8), {(3)AlMe}2 (9), {(4)AlMe}2 (10), {(5)AlMe}2 (11) and {(6)AlMe}2 (12) have been prepared in good yields by alkane elimination from AlMe3 and chiral biaryl-based N2O ligands, (S)-2-(pyrrol-2-methyleneamino)-2′-hydroxy-1,1′-binaphthyl (1H2), (S)-5,5′,6,6′,7,7′,8,8′-octahydro-2-(pyrrol-2-methyleneamino)-2′-hydroxy-1,1′-binaphthyl (2H2), (S)-2-(pyrrol-2-methyleneamino)-2′-hydroxy-6,6′-dimethyl-1,1′-biphenyl (3H2), (S)-2-(pyridine-2-ylmethylamino)-2′-hydroxy-1,1′-binaphthyl (4H2), (S)-5,5′,6,6′,7,7′,8,8′-octahydro-2-(pyridine-2-ylmethylamino)-2′-hydroxy-1,1′-binaphthyl (5H2), and (S)-2-(pyridine-2-ylmethylamino)-2′-hydroxy-6,6′-dimethyl-1,1′-biphenyl (6H2), which are derived from (S)-2-amino-2′-hydroxy-1,1′-binaphthyl or (S)-2-amino-2′-hydroxy-6,6′-dimethyl-1,1′-biphenyl, respectively. Complexes 7–12 have been characterized by various spectroscopic techniques, elemental analyses, and X-ray diffraction analyses. Complex 7 derived from 1H2, has a C2v quasi-symmetric N4AlO2AlMe2 core structure, while complexes 8 and 10 derived from 2H2 or 4H2, adopt a C2 quasi-symmetric MeN2AlO2AlN2Me core structure, indicating that the steric effect of the ligand plays an important role in the complex formation. Complexes 7–12 are active catalysts for the polymerization of rac-lactide in the presence of isopropanol, leading to the heterotactic-rich polylactides.A new series of binuclear aluminum complexes have been prepared from chiral biaryl-based N2O ligands. The aluminum complexes are active catalysts for the polymerization of rac-lactide, leading to the heterotactic-rich polylactides.
Co-reporter:Ning Zhao, Qiuwen Wang, Guohua Hou, Haibin Song, Guofu Zi
Inorganic Chemistry Communications 2014 Volume 41() pp:6-10
Publication Date(Web):March 2014
DOI:10.1016/j.inoche.2013.12.023
Co-reporter:Ning Zhao, Qiuwen Wang, Guohua Hou, Haibin Song, Guofu Zi
Inorganica Chimica Acta 2014 Volume 413() pp:128-135
Publication Date(Web):24 March 2014
DOI:10.1016/j.ica.2014.01.009
•A series of chiral mono- and bi-nuclear aluminum complexes have been reported.•Solvent plays an important role in the complex formation and its reactivity.•The aluminum complexes are active catalysts for the polymerization of rac-lactide.•Heterotactic-rich polylactides are obtained.A new series of organoaluminum complexes have been prepared by alkane elimination in good yields from AlMe3 and chiral biaryl Schiff-base NO2 ligands, 1H2-7H2, which are derived from (S)-2-amino-2′-hydroxy-1,1′-binaphthyl or (S)-2-amino-2′-hydroxy-6,6′-dimethyl-1,1′-biphenyl, respectively. However, solvent plays an important role in the formation of the aluminum complexes. For example, treatment of ligand 1H2 with 1 equiv of AlMe3 in THF gives the mononuclear complex (1)AlMe(THF) (8) in 90% yield. While reaction of 2H2, 3H2, 4H2, 5H2, 6H2 or 7H2 with 1 equiv of AlMe3 in benzene gives the binuclear complexes {(2)AlMe}2 (9), {(3)AlMe}2 (10), {(4)AlMe}2 (11), {(5)AlMe}2 (12), {(6)AlMe}2 (13) and {(7)AlMe}2 (14), respectively, in good yields. Complexes 8–14 have been characterized by various spectroscopic techniques, elemental analyses, and X-ray diffraction analyses. The complexes 8–14 are active catalysts for the polymerization of rac-lactide in the presence of isopropanol, leading to the heterotactic-rich polylactides.A new series of organoaluminum complexes have been prepared from chiral biaryl Schiff-base NO2 ligands. The aluminum complexes are active catalysts for the polymerization of rac-lactide, leading to the heterotactic-rich polylactides.
Co-reporter:Ning Zhao, Qiuwen Wang, Guohua Hou, Haibin Song, Guofu Zi
Inorganic Chemistry Communications 2014 Volume 44() pp:86-90
Publication Date(Web):June 2014
DOI:10.1016/j.inoche.2014.03.009
•Four new chiral aluminum complexes have been reported.•They are active catalysts for the polymerization of rac-lactide.•Heterotactic-rich polylactides are obtained.Four new aluminum chloride complexes {(L1)AlCl}2 (5), {(L2)AlCl}2 (6), (L3)AlCl(THF) (7) and (L4)AlCl(THF) (8) have been prepared by alkane elimination in good yields from the reaction of AlEt2Cl and chiral biaryl Schiff-base NO2 ligands, L1H2–L4H2, which are derived from (S)-2-amino-2′-hydroxy-1,1′-binaphthyl or (S)-2-amino-2′-hydroxy-6,6′-dimethyl-1,1′-biphenyl, respectively. Treatment of ligand L1H2 or L2H2 with 1 equiv of AlEt2Cl in benzene gives the binuclear complexes {(L1)AlCl}2 (5) and {(L2)AlCl}2 (6), respectively, in good yields. Reactions of L3H2 or L4H2 with 1 equiv of AlEt2Cl in THF gives the mononuclear complexes (L3)AlCl(THF) (7) and (L4)AlCl(THF) (8), respectively, in good yields. Complexes 5–8 have been characterized by various spectroscopic techniques, elemental analyses, and X-ray diffraction analyses. The complexes 5–8 are active catalysts for the polymerization of rac-lactide in the presence of propylene oxide (PO), leading to the heterotactic-rich polylactides.A new series of aluminum complexes have been prepared from chiral biaryl Schiff-base NO2 ligands. The aluminum complexes are active catalysts for the polymerization of rac-lactide, leading to the heterotactic-rich polylactides.
Co-reporter:Dr. Wenshan Ren;Enwei Zhou;Bo Fang;Dr. Guohua Hou; Guofu Zi; De-Cai Fang;Dr. Marc D. Walter
Angewandte Chemie International Edition 2014 Volume 53( Issue 42) pp:11310-11314
Publication Date(Web):
DOI:10.1002/anie.201406191
Abstract
The reaction of the base-free terminal thorium imido complex [{η5-1,2,4-(Me3C)3C5H2}2ThN(p-tolyl)] (1) with p-azidotoluene yielded irreversibly the tetraazametallacyclopentene [{η5-1,2,4-(Me3C)3C5H2}2Th{N(p-tolyl)NNN(p-tolyl)}] (2), whereas the bridging imido complex [{[η5-1,2,4-(Me3C)3C5H2]Th(N3)2}2{μ-N(p-tolyl)}2][(n-C4H9)4N]2 (3) was isolated from the reaction of 1 with [(n-C4H9)4N]N3. Unexpectedly, upon the treatment of 1 with 9-diazofluorene, the NN bond was cleaved, an N atom was transferred, and the η2-diazenido iminato complex [{η5-1,2,4-(Me3C)3C5H2}2Th{η2-[NN(p-tolyl)]}{N(9-C13H8)}] (4) was formed. In contrast, the reaction of 1 with Me3SiCHN2 gave the nitrilimido complex [{η5-1,2,4-(Me3C)3C5H2}2Th{NH(p-tolyl)}{N2CSiMe3}] (5), which slowly converted into [{η5-1,2,4-(Me3C)3C5H2}{η5:κ-N-1,2-(Me3C)2-4-CMe2(CH2NNCHSiMe3)C5H2}Th{NH(p-tolyl)}] (6) by intramolecular CH bond activation. The experimental results are complemented by density functional theory (DFT) studies.
Co-reporter:Dr. Wenshan Ren;Enwei Zhou;Bo Fang;Dr. Guohua Hou; Guofu Zi; De-Cai Fang;Dr. Marc D. Walter
Angewandte Chemie 2014 Volume 126( Issue 42) pp:11492-11496
Publication Date(Web):
DOI:10.1002/ange.201406191
Abstract
The reaction of the base-free terminal thorium imido complex [{η5-1,2,4-(Me3C)3C5H2}2ThN(p-tolyl)] (1) with p-azidotoluene yielded irreversibly the tetraazametallacyclopentene [{η5-1,2,4-(Me3C)3C5H2}2Th{N(p-tolyl)NNN(p-tolyl)}] (2), whereas the bridging imido complex [{[η5-1,2,4-(Me3C)3C5H2]Th(N3)2}2{μ-N(p-tolyl)}2][(n-C4H9)4N]2 (3) was isolated from the reaction of 1 with [(n-C4H9)4N]N3. Unexpectedly, upon the treatment of 1 with 9-diazofluorene, the NN bond was cleaved, an N atom was transferred, and the η2-diazenido iminato complex [{η5-1,2,4-(Me3C)3C5H2}2Th{η2-[NN(p-tolyl)]}{N(9-C13H8)}] (4) was formed. In contrast, the reaction of 1 with Me3SiCHN2 gave the nitrilimido complex [{η5-1,2,4-(Me3C)3C5H2}2Th{NH(p-tolyl)}{N2CSiMe3}] (5), which slowly converted into [{η5-1,2,4-(Me3C)3C5H2}{η5:κ-N-1,2-(Me3C)2-4-CMe2(CH2NNCHSiMe3)C5H2}Th{NH(p-tolyl)}] (6) by intramolecular CH bond activation. The experimental results are complemented by density functional theory (DFT) studies.
Co-reporter:GuoFu Zi
Science China Chemistry 2014 Volume 57( Issue 8) pp:1064-1072
Publication Date(Web):2014 August
DOI:10.1007/s11426-014-5094-y
Organoactinide complexes containing terminal metal-ligand multiple bonds have received widespread attention over the past three decades. In the last few years, significant progress has been made in the synthesis and characterization of the imido, oxo, sulfido, and carbene-containing complexes of thorium. Such thorium complexes are of interest because of their unique structural properties, their potential application in novel group transfer reactions and catalysis, as well as their ability to engage the 5f orbitals in metal-ligand bonding. This short review summarizes the synthesis and reactivity of these thorium complexes.
Co-reporter:Wenshan Ren, Wayne W. Lukens, Guofu Zi, Laurent Maron and Marc D. Walter
Chemical Science 2013 vol. 4(Issue 3) pp:1168-1174
Publication Date(Web):10 Jan 2013
DOI:10.1039/C2SC22013J
Bipyridyl thorium metallocenes [η5-1,2,4-(Me3C)3C5H2]2Th(bipy) (1) and [η5-1,3-(Me3C)2C5H3]2Th(bipy) (2) have been investigated by magnetic susceptibility and computational studies. The magnetic susceptibility data reveal that 1 and 2 are not diamagnetic, but they behave as temperature independent paramagnets (TIPs). To rationalize this observation, density functional theory (DFT) and complete active space self-consistent field (CASSCF) calculations have been undertaken, which indicated that Cp′2Th(bipy) has indeed a Th(IV)(bipy2−) ground state (f0d0π*2, S = 0), but the open-shell singlet (f0d1π*1, S = 0) (almost degenerate with its triplet congener) is only 9.2 kcal mol−1 higher in energy. Complexes 1 and 2 react cleanly with Ph2CS to give [η5-1,2,4-(Me3C)3C5H2]2Th[(bipy)(SCPh2)] (3) and [η5-1,3-(Me3C)2C5H3]2Th[(bipy)(SCPh2)] (4), respectively, in quantitative conversions. Since no intermediates were observed experimentally, this reaction was also studied computationally. Whereas coordination of Ph2CS to 2 in its S = 0 ground state is not possible, Ph2CS can coordinate to 2 in its triplet state (S = 1) upon which a single electron transfer (SET) from the (bipy2−) fragment to Ph2CS followed by C–C coupling takes place.
Co-reporter:Liang Chen, Ning Zhao, Qiuwen Wang, Guohua Hou, Haibin Song, Guofu Zi
Inorganica Chimica Acta 2013 Volume 402() pp:140-155
Publication Date(Web):1 June 2013
DOI:10.1016/j.ica.2013.04.008
Highlights•A series of chiral organo-titanium complexes have been prepared.•The steric effect of the ligand plays an important role in the complex formation.•They are active catalysts for the asymmetric hydrophosphonylation of aldehydes.A series of chiral organo-titanium complexes have been prepared from the reaction between Ti(OiPr)4 and chiral biaryl Schiff-base ligands 1H2–12H. The steric demand of the ligand plays an important role in the formation of the titanium complexes. For example, treatment of ligand 1H2 with 1 equiv of Ti(OiPr)4 in toluene at room temperature gives, after recrystallization from a toluene solution, the chiral bis-ligated titanium complex (L1)2Ti (14). While under similar reaction conditions, the more bulky ligands 2H2, 4H2, and 6H2 form the mono-ligated titanium complexes (L2)Ti(OiPr)2 (15), (L4)Ti(OiPr)2 (19), and (L6)Ti(OiPr)2 (22), respectively, in good yields. The mono-ligated titanium alkoxides can be converted to bis-ligated complex via ligand redistribution reaction. For one instance, treatment of mono-ligated complex (L2)Ti(OiPr)2 (15) in benzene at 60 °C results in the isolation of the bis-ligated complex (L2)2Ti (16) in 92% yield. All titanium complexes have been characterized by various spectroscopic techniques and elemental analyses. The solid-state structures of complexes 14–21, 23, 24 and 29 have further been confirmed by X-ray diffraction analyses. The titanium complexes are active catalysts for the asymmetric hydrophosphonylation of aromatic aldehydes with moderate enantioselectivities.Graphical abstractA series of chiral organo-titanium complexes have been prepared. They are active catalysts for the asymmetric hydrophosphonylation of aromatic aldehydes with moderate enantioselectivities.
Co-reporter:Haibin Song, Dongna Fan, Yuqiao Liu, Guohua Hou, Guofu Zi
Journal of Organometallic Chemistry 2013 729() pp: 40-45
Publication Date(Web):
DOI:10.1016/j.jorganchem.2013.01.020
Co-reporter:Wenshan Ren, Haibin Song, Guofu Zi and Marc D. Walter
Dalton Transactions 2012 vol. 41(Issue 19) pp:5965-5973
Publication Date(Web):30 Mar 2012
DOI:10.1039/C2DT00051B
The synthesis, structure and reactivity of a new bipy thorium metallocene have been studied. The reduction of the thorium chloride metallocene [η5-1,3-(Me3C)2C5H3]2ThCl2 (1) with potassium graphite in the presence of 2,2′-bipyridine gives the purple bipy metallocene [η5-1,3-(Me3C)2C5H3]2Th(bipy) (2) in good yield. Complex 2 has been fully characterized by various spectroscopic techniques, elemental analysis and X-ray diffraction analysis. Complex 2 reacts cleanly with trityl chloride, silver halides and diphenyl diselenide, leading to the halide metallocenes [η5-1,3-(Me3C)2C5H3]2ThX2 (X = Cl (1), Br (3), I (4)) and [η5-1,3-(Me3C)2C5H3]2Th(F)(μ-F)3Th[η5-1,3-(Me3C)2C5H3](F)(bipy) (5), and selenido metallocene [η5-1,3-(Me3C)2C5H3]2Th(SePh)2 (6), in good conversions. In addition, 2 cleaves the CS bond of CS2 to give the sulfido complex, [η5-1,3-(Me3C)2C5H3]2ThS (7), which further undergoes an irreversible dimerization or nucleophilic addition with CS2, leading to the dimeric sulfido complex {[η5-1,3-(Me3C)2C5H3]2Th}(μ-S)2 (8) and dimeric trithiocarbonate complex {[η5-1,3-(Me3C)2C5H3]2Th}(μ-CS3)2 (10) in good yields, respectively.
Co-reporter:Ning Zhao, Liang Chen, Wenshan Ren, Haibin Song, Guofu Zi
Journal of Organometallic Chemistry 2012 712() pp: 29-36
Publication Date(Web):
DOI:10.1016/j.jorganchem.2012.04.004
Co-reporter:Zhanbin Zhang, Ning Zhao, Wenshan Ren, Liang Chen, Haibin Song, Guofu Zi
Inorganic Chemistry Communications 2012 20() pp: 234-237
Publication Date(Web):
DOI:10.1016/j.inoche.2012.03.015
Co-reporter:Wenshan Ren, Guofu Zi, and Marc D. Walter
Organometallics 2012 Volume 31(Issue 2) pp:672-679
Publication Date(Web):January 5, 2012
DOI:10.1021/om201015f
The reduction of [η5-1,2,4-(Me3C)3C5H2]2ThCl2 (1) with potassium graphite in the presence of 2,2′-bipyridine gives the purple thorium bipy metallocene [η5-1,2,4-(Me3C)3C5H2]2Th(bipy) (2) in good yield. Complex 2 has been characterized by various spectroscopic techniques, elemental analysis, and single-crystal X-ray diffraction. Complex 2 is a good synthon for low-valent thorium, as shown by the reactivity with silver halides, trityl chloride, pyridine-N-oxide, RN3, 9-diazofluorene, and diphenyl diselenide, yielding the halide metallocenes [η5-1,2,4-(Me3C)3C5H2]2ThX2 (X = Cl (1), F (3), Br (4)), oxo metallocene [η5-1,2,4-(Me3C)3C5H2]2ThO(py) (5), imido metallocenes [η5-1,2,4-(Me3C)3C5H2]2Th═NR (R = p-tolyl (6), Ph3C (7), Me3Si (8), (9-C13H8)═N (9)), and selenido complex [η5-1,2,4-(Me3C)3C5H2]Th(SePh)3(bipy) (10a), in quantitative conversions.
Co-reporter:Wenshan Ren ; Guofu Zi ; De-Cai Fang ;Marc D. Walter
Journal of the American Chemical Society 2011 Volume 133(Issue 33) pp:13183-13196
Publication Date(Web):July 27, 2011
DOI:10.1021/ja205280k
The synthesis, structure, and reactivity of thorium oxo and sulfido metallocenes have been comprehensively studied. Heating of an equimolar mixture of the dimethyl metallocene [η5-1,2,4-(Me3C)3C5H2]2ThMe2 (2) and the bis-amide metallocene [η5-1,2,4-(Me3C)3C5H2]2Th(NH-p-tolyl)2 (3) in refluxing toluene results in the base-free imido thorium metallocene, [η5-1,2,4-(Me3C)3C5H2]2Th═N(p-tolyl) (4), which is a useful precursor for the preparation of oxo and sulfido thorium metallocenes [η5-1,2,4-(Me3C)3C5H2]2Th═E (E = O (5) and S (15)) by cycloaddition–elimination reaction with Ph2C═E (E = O, S) or CS2. The oxo metallocene 5 acts as a nucleophile toward alkylsilyl halides, while sulfido metallocene 15 does not. The oxo metallocene 5 and sulfido metallocene 15 undergo a [2 + 2] cycloaddition reaction with Ph2CO, CS2, or Ph2CS, but they show no reactivity with alkynes. Density functional theory (DFT) studies provide insights into the subtle interplay between steric and electronic effects and rationalize the experimentally observed reactivity patterns. A comparison between Th, U, and group 4 elements shows that Th4+ behaves more like an actinide than a transition metal.
Co-reporter:Wenshan Ren, Xuebin Deng, Guofu Zi and De-Cai Fang
Dalton Transactions 2011 vol. 40(Issue 38) pp:9662-9664
Publication Date(Web):04 Aug 2011
DOI:10.1039/C1DT11149C
The first thorium poly-carbene complexes [(Ph2PS)2C]2Th(DME) (2) and [{[(Ph2PS)2C]3Th}Li2(DME)]n (3) have been prepared and structurally characterized. DFT calculations reveal that the ThC bond is polarized toward the nucleophilic carbene carbon atom, which is further verified by the experimental observation that the ThC bond shows a nucleophilic behavior with Ph2CO.
Co-reporter:Furen Zhang, Haibin Song and Guofu Zi
Dalton Transactions 2011 vol. 40(Issue 7) pp:1547-1566
Publication Date(Web):10 Jan 2011
DOI:10.1039/C0DT01229G
A new series of group 5 metal amides have been prepared from the reaction between V(NMe2)4 or M(NMe2)5 (M = Nb, Ta) and chiral ligands, (R)-2,2′-bis(mesitoylamino)-1,1′-binaphthyl (1H2), (R)-5,5′,6,6′,7,7′,8,8′-octahydro-2,2′-bis(mesitoylamino)-1,1′-binaphthyl (2H2), (R)-6,6′-dimethyl-2,2′-bis(mesitoylamino)-1,1′-biphenyl (3H2), (R)-2,2′-bis(mesitylenesulfonylamino)-6,6′-dimethyl-1,1′-biphenyl (4H2), (R)-2,2′-bis(diphenylthiophosphoramino)-1,1′-binaphthyl (5H2), (R)-2,2′-bis[(3-tert-butyl-2-hydroxybenzylidene)amino]-6,6′-dimethyl-1,1′-biphenyl (6H2), (R)-2,2′-bis[(3,5-di-tert-butyl-2-hydroxybenzylidene)amino]-6,6′-dimethyl-1,1′-biphenyl (7H2), (R)-2,2′-bis[(3-tert-butyl-2-hydroxybenzylidene)amino]-1,1′-binaphthyl (8H2), (S)-2-(mesitoylamino)-2′-(dimethylamino)-1,1′-binaphthyl (9H), and (R)-2-(mesitoylamino)-2′-(dimethylamino)-6,6′-dimethyl-1,1′-biphenyl (10H), which are derived from (R) or (S)-2,2′-diamino-1,1′-binaphthyl, and (R)-2,2′-diamino-6,6′-dimethyl-1,1′-biphenyl, respectively. Treatment of V(NMe2)4 or M(NMe2)5 (M = Nb, Ta) with 1 equiv of C2-symmetric amidate ligands 1H2, 2H2, 3H2, 4H2, and 5H2, or Schiff base ligands 6H2, 7H2 and 8H2 at room temperature gives, after recrystallization from a benzene, toluene or n-hexane solution, the vanadium amides (1)V(NMe2)2 (11), (2)V(NMe2)2 (14), (3)V(NMe2)2 (17), (5)V(NMe2)2 (22), (6)V(NMe2)2 (23) and (7)V(NMe2)2 (24), and niobium amides (1)Nb(NMe2)3 (12), (2)Nb(NMe2)3 (15), (3)Nb(NMe2)3 (18), (4)Nb(NMe2)3 (20) and [2-(3-Me3C-2-O-C6H3CHN)-2′-(N)-C20H12][2-(Me2N)2CH-6-CMe3-C6H3O]NbNMe2·C7H8 (25·C7H8), and tantalum amides (1)Ta(NMe2)3 (13), (2)Ta(NMe2)3 (16), (3)Ta(NMe2)3 (19) and (4)Ta(NMe2)3 (21) respectively, in good yields. Reaction of V(NMe2)4 or M(NMe2)5 (M = Nb, Ta) with 2 equiv of C1-symmetric amidate ligands 9H or 10H at room temperature gives, after recrystallization from a toluene or n-hexane solution, the chiral bis-ligated vanadium amides (9)2V(NMe2)2·3C7H8 (27·3C7H8) and (10)V(NMe2)2 (28), and chiral bis-ligated metallaaziridine complexes (10)2M(NMe2)(η2-CH2NMe) (M = Nb (29), Ta (30)) respectively, in good yields. The niobium and tantalum amidate complexes are stable in a toluene solution at or below 160 °C, while the vanadium amidate complexes degrade viadiemthylamino group elimination at this temperature. For example, heating the complex (2)V(NMe2)2 (14) in toluene at 160 °C for four days leads to the isolation of the complex [(2)V]2(μ-NMe2)2 (26) in 58% yield. These new complexes have been characterized by various spectroscopic techniques, and elemental analyses. The solid-state structures of complexes 12, 13, and 15–30 have further been confirmed by X-ray diffraction analyses. The vanadium amides are active chiral catalysts for the asymmetric hydroamination/cyclization of aminoalkenes, affording cyclic amines in moderate to good yields with good ee values (up to 80%), and the tantalum amides are outstanding chiral catalysts for the hydroaminoalkylation, giving chiral secondary amines in good yields with excellent ee values (up to 93%).
Co-reporter:Haiyan Zhang, Liang Chen, Haibin Song, Guofu Zi
Inorganica Chimica Acta 2011 Volume 366(Issue 1) pp:320-336
Publication Date(Web):30 January 2011
DOI:10.1016/j.ica.2010.11.023
A series of chiral Ag(I) and Cu(II) complexes have been prepared from the reaction between AgX (X = NO3, PF6, OTf) or CuX2 (X = Cl, ClO4) and chiral biaryl-based N-ligands. The rigidity of the ligand plays an important role in the Ag(I) complex formation. For example, treatment of chiral N3-ligands 1–3 with half equiv of AgX (X = NO3, PF6, OTf) gives the chiral bis-ligated four-coordinated Ag(I) complexes, while ligand 4 affords the two-coordinated Ag(I) complexes. Reaction of AgX with 1 equiv of chiral N4-ligands 5, 7, 8 and 10 gives the chiral, binuclear double helicate Ag(I) complexes, while chiral mono-nuclear single helicate Ag(I) complexes are obtained with N4-ligands 6 and 9. Treatment of either N3-ligand 1 or N4-ligand 9 or 10 with 1 equiv of CuX2 (X = Cl, ClO4) gives the mono-ligated Cu(II) complexes. All the complexes have been characterized by various spectroscopic techniques, and elemental analyses. Seventeen of them have further been confirmed by X-ray diffraction analyses. The Cu(II) complexes do not show catalytic activity for allylation reaction, in contrast to Ag(I) complexes, but they do exhibit catalytic activity for Henry reaction (nitroaldol reaction) that Ag(I) complexes do not.Graphical abstractA series of chiral Ag(I) and Cu(II) complexes have been prepared. The Cu(II) complexes do not show catalytic activity for allylation reaction, in contrast to Ag(I) complexes, but they do show catalytic activity for Henry reaction (nitroaldol reaction) that Ag(I) complexes do not.Research highlights► A series of chiral Ag(I) and Cu(II) complexes have been prepared and structural characterized. ► The rigidity of the ligand plays an important role in the Ag(I) complexes formation and their catalytic activity. ► The chiral Ag(I) complexes are active catalysts for asymmetric allylation reaction, and the chiral Cu(II) complexes are active catalysts for asymmetric Henry reaction (nitroaldol reaction).
Co-reporter:Furen Zhang, Jiaxin Zhang, Haibin Song, Guofu Zi
Inorganic Chemistry Communications 2011 Volume 14(Issue 1) pp:72-74
Publication Date(Web):January 2011
DOI:10.1016/j.inoche.2010.09.034
Two new chiral organoyttrium amidate complexes 1-Y[N(SiMe3)2]2 (3) and 2-Y[N(SiMe3)2]2·C6H12 (4·C6H12) have been readily prepared in good yields by silylamine elimination reaction between Y[N(SiMe3)2]3 and chiral binaphthyl-based amidate ligands, (R)-2,2′-bis(mesitoylamino)-1,1′-binaphthyl (1) and (S)-2-(mesitoylamino)-2′-(dimethylamino)-1,1′-binaphthyl (2), respectively. Complexes 2 and 3 have been characterized by various spectroscopic techniques, elemental analyses, and X-ray diffraction analyses. Complexes 3 and 4 are active catalysts for the polymerization of rac-lactide, leading to the isotactic-rich polylactides.Two new chiral rare earth metal amidate complexes have been prepared. Both complexes are active catalysts for the polymerization of rac-lactide, leading to the isotactic-rich polylactides.
Co-reporter:Wenshan Ren, Ning Zhao, Liang Chen, Haibin Song, Guofu Zi
Inorganic Chemistry Communications 2011 Volume 14(Issue 11) pp:1838-1841
Publication Date(Web):November 2011
DOI:10.1016/j.inoche.2011.08.021
Treatment of ThCl4(tmeda)2 with 3 equiv of [η5-1,3-(Me3C)2C5H3]K in toluene under reflux gives the tris-Cp chloride complex [η5-1,3-(Me3C)2C5H3]3ThCl (1) in 75% yield. The chlorine atom can be replaced by other groups via metathesis reactions. For example, reaction of 1 with an excess of KH in toluene under reflux affords the hydride complex [η5-1,3-(Me3C)2C5H3]3ThH (2) in 68% yield. Complexes 1 and 2 have been characterized by various spectroscopic techniques, elemental analyses, and X-ray diffraction analyses. Complex 2 is an active catalyst for the polymerization of rac-lactide, leading to the atactic polylactides with high molecular weights and narrow molecular weight distributions.A new organothorium hydride complex has been prepared and structurally characterized. It is an active catalyst for the polymerization of rac-lactide, leading to the atactic polylactides.Highlights► A new organothorium hydride complex has been prepared and structurally characterized. ► It is an active catalyst for the polymerization of rac-lactide, leading to the atactic polylactides. ► The first example of the polymerization of lactide initiated by organoactinide complex has been reported.
Co-reporter:Wenshan Ren; Guofu Zi; De-Cai Fang;Dr. Marc D. Walter
Chemistry - A European Journal 2011 Volume 17( Issue 45) pp:12669-12682
Publication Date(Web):
DOI:10.1002/chem.201101972
Abstract
The synthesis, structure, and reactivity of a base-free thorium terminal-imido metallocene have been comprehensively studied. Treatment of thorium metallocenes [{η5-1,2,4-(Me3C)3C5H2}2ThMe2] and [{η5-1,3-(Me3C)2C5H3}2ThMe2] with RNH2 gives diamides [{η5-1,2,4-(Me3C)3C5H2}2Th(NHR)2] (R=Me (7), p-tolyl (8)) and [{η5-1,3-(Me3C)2C5H3}2Th(NH-p-tolyl)2] (9), respectively. Diamides 7 and 9 do not eliminate methylamine or p-toluidine, but sublime without decomposition at 150 °C under vacuum (0.01 mmHg), whereas diamide 8 is converted at 140 °C/0.01 mmHg into the primary amine p-tolyl-NH2 and [{η5-1,2,4-(Me3C)3C5H2}2ThN(p-tolyl)] (10), which may be isolated in pure form. Imido metallocene 10 does not react with electrophiles such as alkylsilyl halides; however, it reacts with electron-rich or unsaturated reagents. For example, reaction of 10 with sulfur affords the metallacycle [{η5-1,2,4-(Me3C)3C5H2}2Th{N(p-tolyl)S-S}]. Imido 10 is an important intermediate in the catalytic hydroamination of internal alkynes, and an efficient catalyst for the trimerization of PhCN. Density functional theory (DFT) studies provide a detailed understanding of the experimentally observed reactivity patterns.
Co-reporter:Qiuwen Wang, Furen Zhang, Haibin Song, Guofu Zi
Journal of Organometallic Chemistry 2011 696(10) pp: 2186-2192
Publication Date(Web):
DOI:10.1016/j.jorganchem.2010.11.032
Co-reporter:Guofu Zi
Journal of Organometallic Chemistry 2011 696(1) pp: 68-75
Publication Date(Web):
DOI:10.1016/j.jorganchem.2010.07.034
Co-reporter:Guofu Zi, Furen Zhang and Haibin Song
Chemical Communications 2010 vol. 46(Issue 34) pp:6296-6298
Publication Date(Web):29 Jul 2010
DOI:10.1039/C0CC01265C
A highly enantioselective group 5 metal amide catalyst system is reported for the hydroaminoalkylation of secondary amines to give chiral amines in good yields with excellent ee values (up to 93%) by loading of 5% precatalyst.
Co-reporter:Guofu Zi, Furen Zhang, Li Xiang, Yue Chen, Weihai Fang and Haibin Song
Dalton Transactions 2010 vol. 39(Issue 17) pp:4048-4061
Publication Date(Web):23 Feb 2010
DOI:10.1039/B923457H
A new series of titanium(IV) and zirconium(IV) amides have been prepared from the reaction between M(NMe2)4 (M = Ti, Zr) and chiral ligands, (R)-2,2′-bis(p-toluenesulfonylamino)-1,1′-binaphthyl (1H2), (R)-2,2′-bis(diphenylphosphinoylamino)-1,1′-binaphthyl (2H2), (R)-2,2′-bis(mesitoylamino)-1,1′-binaphthyl (3H2), (R)-5,5′,6,6′,7,7′,8,8′-octahydro-2,2′-bis(pyrrol-2-ylmethyleneamino)-1,1′-binaphthyl (4H2), (R)-5,5′,6,6′,7,7′,8,8′-octahydro-2,2′-bis(mesitoylamino)-1,1′-binaphthyl (5H2), and (R)-5,5′,6,6′,7,7′,8,8′-octahydro-2,2′-bis(mesitylenesulfonylamino)-1,1′-binaphthyl (6H2), which are derived from (R)-2,2′-diamino-1,1′-binaphthyl. Reaction of M(NMe2)4 with 1 equiv of arylsulfonylamides 1H2 and 6H2, diphenylphosphoramide 2H2, mesitoylamides 3H2 and 5H2, or Schiff base ligand 4H2 at room temperature gives, after recrystallization from a benzene, toluene or n-hexane solution, the chiral titanium amides (1)Ti(NMe2)2·3C6H6 (7·3C6H6), (4)Ti(NMe2)2 (11), (5)Ti(NMe2)2 (13) and (6)Ti(NMe2)2 (15), and zirconium amides (1)Zr(NMe2)2 (8), (2)Zr(NMe2)2 (9), (3)Zr(NMe2)2 (10), (4)Zr(NMe2)2 (12), (5)Zr(NMe2)2 (14) and (6)Zr(NMe2)2·C7H8 (16·C7H8) respectively, in good yields. These amides are stable below 90 °C in toluene solution, but they degrade via ligand redistribution at a higher temperature. For example, treatment of (1)Zr(NMe2)2 (8) or (5)Zr(NMe2)2 (14) in refluxing toluene for three days leads to the isolation of the complexes (1)2Zr·C7H8 (17·C7H8) and (5)2Zr·3C7H8 (18·3C7H8) respectively, in moderate yields. These new compounds have been characterized by various spectroscopic techniques, and elemental analyses. The solid-state structures of compounds 7–9, 11–13, and 15–18 have further been confirmed by X-ray diffraction analyses. The titanium amide 13 and all the zirconium amides are active catalysts for the asymmetric hydroamination/cyclization of aminoalkenes, affording cyclic amines in moderate to excellent yields with moderate to excellent ee values (up to 93%). Theoretical studies reveal the interaction between the carbon chain of the substrate and the sterically demanding ligand groups plays a key role in the stereodirection of the enantioselection during the ZrN bond approaches to the CC bond.
Co-reporter:Li Xiang, Furen Zhang, Jiaxin Zhang, Haibin Song, Guofu Zi
Inorganic Chemistry Communications 2010 Volume 13(Issue 5) pp:666-670
Publication Date(Web):May 2010
DOI:10.1016/j.inoche.2010.03.015
Five group 4 metal complexes (1)2Zr(NMe2)2 (5), (2)2Ti(NMe2)2 (6), (2)2Zr(NMe2)2 (7), (3)2Zr (8) and (4)2Ti(NMe2)2 (9) have been readily prepared from the reaction between M(NMe2)4 (M = Ti, Zr) and chiral binaphthyldiamine-based ligands, (R)-2,2′-bis(diphenylthiophosphoramino)-1,1′-binaphthyl (1H2), (R)-5,5′,6,6′,7,7′,8,8′-octahydro-2,2′-bis(diphenylthiophosphoramino)-1,1′-binaphthyl (2H2), (R)-5,5′,6,6′,7,7′,8,8′-octahydro-2,2′-bis(methanesulphonylamino)-1,1′-binaphthyl (3H2), and C1-symmetric ligand, (R)-2-(mesitylenesulphonylamino)-2′-(dimethylamino)-1,1′-binaphthyl (4H). All the complexes have been characterized by various spectroscopic techniques, elemental analyses and X-ray diffraction analyses. The zirconium amides are active catalysts for the asymmetric hydroamination/cyclization of aminoalkenes, affording cyclic amines in good yields with moderate ee (enantiomeric excess) values.A new series of chiral group 4 metal complexes have been prepared. The zirconium amides are effective catalysts for the asymmetric hydroamination/cyclization of aminoalkenes, affording cyclic amines in good yields with moderate ee values.
Co-reporter:Guofu Zi, Li Xiang, Xue Liu, Qiuwen Wang, Haibin Song
Inorganic Chemistry Communications 2010 Volume 13(Issue 3) pp:445-448
Publication Date(Web):March 2010
DOI:10.1016/j.inoche.2010.01.008
The chiral biaryl-based N4-ligands, (R)-5,5′,6,6′,7,7′,8,8′-octahydro-2,2′-bis(pyrrol-2-ylmethyleneamino)-1,1′-binaphthyl (1H2) and (S)-2,2′-bis(pyrrol-2-ylmethyleneamino)-6,6′-dimethyl-1,1′-biphenyl (2H2), can effectively stabilize the chiral rare earth metal chloride complexes such as 1-YCl(dme) (3) and 2-YCl(dme) (4), which offers important intermediates for the preparation of chiral rare earth catalysts containing the M–C or M–X (X = heteroatom) bonds. For example, treatment of 3 with half equiv of 1Na2 in THF gives the binuclear complex 1-Y(thf)-1-Y(thf)-1 (5) in 70% yield. These complexes have been characterized by various spectroscopic techniques, elemental analyses, and X-ray diffraction analyses. The complex 5 is an active catalyst for the ring-opening polymerization of rac-lactide, affording isotactic-rich polylactides.The chiral biaryl-based N4-ligands can effectively stabilize the rare earth metal chloride complexes, which offers important intermediates for the preparation of rare earth catalysts containing the M–C or M–X (X = heteroatom) bonds.
Co-reporter:Furen Zhang, Haibin Song, Guofu Zi
Journal of Organometallic Chemistry 2010 695(17) pp: 1993-1999
Publication Date(Web):
DOI:10.1016/j.jorganchem.2010.05.003
Co-reporter:Qiuwen Wang, Haibin Song, Guofu Zi
Journal of Organometallic Chemistry 2010 695(10–11) pp: 1583-1591
Publication Date(Web):
DOI:10.1016/j.jorganchem.2010.03.014
Co-reporter:Guofu Zi, Furen Zhang, Xue Liu, Lin Ai, Haibin Song
Journal of Organometallic Chemistry 2010 695(5) pp: 730-739
Publication Date(Web):
DOI:10.1016/j.jorganchem.2009.12.008
Co-reporter:Guofu Zi
Dalton Transactions 2009 (Issue 42) pp:9101-9109
Publication Date(Web):22 Jul 2009
DOI:10.1039/B906588A
The development of catalysts for intramolecular asymmetric alkene hydroamination has been investigated extensively over the past two decades, since the hydroamination is a highly atom economical process in which an amine N–H bond is added to an unsaturated carbon–carbon bond leading to the formation of nitrogen heterocycles that are building blocks in numerous biologically and pharmacologically active compounds. The organolanthanide catalysts have been shown to be promising in this area. This perspective highlights the recent progress in the development of organolanthanide catalysts with chiral biaryl-backbones for the asymmetric hydroamination/cyclization of non-activated alkenes.
Co-reporter:Zhanbin Zhang, Xuemei Bai, Ruochen Liu, Guofu Zi
Inorganica Chimica Acta 2009 Volume 362(Issue 6) pp:1687-1691
Publication Date(Web):20 April 2009
DOI:10.1016/j.ica.2008.07.019
A new series of chiral cis-3-aminoazetidines have been prepared from (S)-1-phenylethylamine. The catalytic activity of the new ligands has been tested in standard asymmetric reactions, in most cases moderate to good yields and moderate enantioselectivity have been observed.A new series of chiral cis-3-aminoazetidines have been prepared from (S)-1-phenylethylamine. They exhibit moderate to good catalytic activities and moderate enantiomeric selectivities in most investigated asymmetric reactions.
Co-reporter:Haibin Song, Li-Na Gu, Guofu Zi
Journal of Organometallic Chemistry 2009 694(9–10) pp: 1493-1502
Publication Date(Web):
DOI:10.1016/j.jorganchem.2008.12.059
Co-reporter:Qiuwen Wang, Li Xiang, Haibin Song, Guofu Zi
Journal of Organometallic Chemistry 2009 694(5) pp: 691-696
Publication Date(Web):
DOI:10.1016/j.jorganchem.2008.11.061
Co-reporter:Guofu Zi, Xue Liu, Li Xiang and Haibin Song
Organometallics 2009 Volume 28(Issue 4) pp:1127-1137
Publication Date(Web):January 27, 2009
DOI:10.1021/om801061v
A new series of titanium(IV) and zirconium(IV) amides have been prepared from the reaction between M(NMe2)4 (M = Ti, Zr) and chiral ligands, (S)-2-(pyrrol-2-ylmethyleneamino)-2′-(dimethylamino)-1,1′-binaphthyl (4H), (R)-2-(pyridin-2-ylmethylamino)-2′-(dimethylamino)-6,6′-dimethyl-1,1′-biphenyl (6H), (S)-2-(diphenylphosphinoylamino)-2′-(dimethylamino)-1,1′-binaphthyl (7H), (R)-2-(diphenylphosphinoylamino)-2′-(dimethylamino)-6,6′-dimethyl-1,1′-biphenyl (8H), (S)-2-(mesitoylamino)-2′-(dimethylamino)-1,1′-binaphthyl (9H), (R)-2-(mesitoylamino)-2′-(dimethylamino)-6,6′-dimethyl-1,1′-biphenyl (10H), and (R)-5,5′6,6′7,7′8,8′-octahydro-2-(mesitoylamino)-2′-(dimethylamino)-1,1′-binaphthyl (11H), which are derived from (S)-2-amino-2′-(dimethylamino)-1,1′-binaphthyl (1), (R)-2-amino-2′-(dimethylamino)-6,6′-dimethyl-1,1′-biphenyl (2), or (R)-5,5′6,6′7,7′8,8′-octahydro-2-amino-2′-(dimethylamino)-1,1′-binaphthyl (3). Reaction of M(NMe2)4 with 2 equiv of 4H or 6H gives, after recrystallization from an n-hexane solution, the monoligated chiral titanium amides (4)Ti(NMe2)3 (12), (6)Ti(NMe2)3 (13), and zirconium amide (6)Zr(NMe2)3 (14), respectively, in good yields. Under similar reaction conditions, treatment of Zr(NMe2)4 with 2 equiv of diphenylphosphoramide 7H or 8H affords, after recrystallization from a toluene solution, the bis-ligated chiral zirconium amides (7)2Zr(NMe2)2·2C7H8 (15·2C7H8) and (8)2Zr(NMe2)2 (16), respectively, in good yields. Reaction of M(NMe2)4 (M = Ti, Zr) with 2 equiv of mesitoylamide 9H, 10H, or 11H also gives, after recrystallization from a toluene or n-hexane solution, the bis-ligated chiral titanium amides (9)2Ti(NMe2)2·2.75C7H8 (17·2.75C7H8) and (10)2Ti(NMe2)2 (19) and zirconium amides (9)2Zr(NMe2)2·C7H8 (18·C7H8), (10)2Zr(NMe2)2 (20), and (11)2Zr(NMe2)2 (21), respectively, in good yields. All new compounds have been characterized by various spectroscopic techniques and elemental analyses. The solid-state structures of compounds 1, 2, 9H, and 12−20 have further been confirmed by X-ray diffraction analyses. The zirconium amides are active catalysts for the asymmetric hydroamination/cyclization of aminoalkenes, affording cyclic amines in good to excellent yields with good ee values, while the titanium amides are not.
Co-reporter:Qiuwen Wang, Li Xiang, Haibin Song and Guofu Zi
Inorganic Chemistry 2008 Volume 47(Issue 10) pp:4319-4328
Publication Date(Web):April 15, 2008
DOI:10.1021/ic702461f
A new series of amidolanthanides have been prepared from the reactions between Ln[N(SiMe3)2]3 and the chiral NNO ligands, (S)-2-(pyrrol-2-ylmethyleneamino)-2′-hydroxy-6,6′-dimethyl-1,1′-biphenyl (2H2) and (S)-5,5′,6,6′,7,7′,8,8′-octahydro-2-(pyrrol-2-ylmethyleneamino)-2′-hydroxy-1,1′-binaphthyl (3H2), which are synthesized from the condensation of pyrrole-2-carboxaldehyde with 1 equiv of (S)-2-amino-2′-hydroxy-6,6′-dimethyl-1,1′-biphenyl or (S)-5,5′,6,6′,7,7′,8,8′-octahydro-2-amino-2′-hydroxy-1,1′-binaphthyl, in the presence of molecular sieves at 70 °C, respectively. Treatment of 2H2 with 1 equiv of Ln[N(SiMe3)2]3 (Ln = Sm, Yb) in toluene under reflux, followed by recrystallization from a toluene solution, gives the dimeric amido complexes, {2-SmN(SiMe3)2}2·0.5C7H8 (6·0.5C7H8) and {2-YbN(SiMe3)2}2·1.5C7H8 (8·1.5C7H8), in good yields. While under similar reaction conditions, the reaction of 2H2 with 1 equiv of Y[N(SiMe3)2]3 leads to the isolation of a mixture of {2-YN(SiMe3)2}2 (7a) and {(2)2Y}Y[N(SiMe3)2]2 (7b) in 82% total yield; the reaction of 3H2 with 1 equiv of Ln[N(SiMe3)2]3 (Ln = Y, Yb) gives the trinuclear complexes, {(3)2Ln}2LnN(SiMe3)2·1.5C7H8 (Ln = Y (9·1.5C7H8), Yb (10·1.5C7H8)), in good yields. All compounds have been characterized by various spectroscopic techniques and elemental analyses. The solid-state structures of compounds 2H2 and 6−10 have been further confirmed by X-ray diffraction analyses. Complexes 6−9 are active catalysts for the asymmetric hydroamination/cyclization of aminoalkenes, affording cyclic amines in good yields with moderate ee values.
Co-reporter:Guofu Zi, Qiuwen Wang, Li Xiang and Haibin Song
Dalton Transactions 2008 (Issue 43) pp:5930-5944
Publication Date(Web):16 Sep 2008
DOI:10.1039/B808238C
A new series of lanthanide and group 4 metal complexes have been prepared from the reactions between Ln[N(SiMe3)2]3 or M(NMe2)4 and chiral ligands, (R)-2-(pyrrol-2-ylmethyleneamino)-2′-methoxy-1,1′-binaphthyl (1H), (S)-5,5′,6,6′,7,7′,8,8′-octahydro-2-(pyrrol-2-ylmethyleneamino)-2′-methoxy-1,1′-binaphthyl (2H) and (R)-2-(pyrrol-2-ylmethyleneamino)-2′-methoxy-6,6′-dimethyl-1,1′-biphenyl (3H). The steric effect of the ligand coupled with the size effect of the ions plays an important role in the formation of the lanthanide complexes. For example, treatment of 1H with 1 equiv of Ln[N(SiMe3)2]3 (Ln = Y, Yb) in toluene gives the tris-ligated complexes, (1)3Y·C7H8 (5·C7H8) and (1)3Yb·2C7H8 (6·2C7H8) in good yields; reaction of 2H with 1 equiv of Sm[N(SiMe3)2]3 also gives the tris-ligated product (2)3Sm (7), while treatment of 2H with 1 equiv of Ln[N(SiMe3)2]3 (Ln = Y, Yb) leads to the isolation of the bis-ligated organolanthanide amides (2)2LnN(SiMe3)2·2C6H6 (Ln = Y (8·2C6H6), Yb (9·2C6H6)) in good yields. Reaction of 1H, 2H or 3H with 1 equiv of M(NMe2)4 gives, after recrystallization from a toluene or benzene solution, the chiral bis-ligated titanium amides (1)2Ti(NMe2)2·0.75C7H8 (10·0.75C7H8), (2)2Ti(NMe2)2 (12), (3)2Ti(NMe2)2·C6H6 (14·C6H6), and zirconium amides (1)2Zr(NMe2)2·C7H8 (11·C7H8), (2)2Zr(NMe2)2 (13), (3)2Zr(NMe2)2·C6H6 (15·C6H6), in good yields, respectively. Treatment of Zr(NMe2)4 with 1 equiv of (R)-2-(pyrrol-2-ylmethylamino)-2′-methoxy-1,1′-binaphthyl (4H2), which was prepared from the reduction of 1H with an excess of NaBH4 in a solvent mixture of MeOH and toluene (1:1) at 50 °C, gives the trinuclear complex [(R)-2-O-C20H12-2′-(NCH2C4H3)]2Zr3(NMe2)6·2C7H8 (16·2C7H8) in 65% yield. Organolanthanide amides and zirconium amides are active catalysts for asymmetric hydroamination/cyclization of aminoalkenes, affording cyclic amines in moderate to good yields with moderate ee values, while the titanium amides are not. During the course of the catalytic reaction, 8 is decomposed leading to the isolation of (2)3Y·C7H8 (17·C7H8) in 35% yield from a toluene solution. The organolanthanide amides are also active catalysts for ring-opening polymerization of rac-lactide, giving isotactic-rich polylactides. All compounds have been characterized by various spectroscopic techniques, and elemental analyses. The solid-state structures of compounds 2H, 3H, 5–11, and 13–17 have further been confirmed by X-ray diffraction analyses.
Co-reporter:Li Xiang;Haibin Song
European Journal of Inorganic Chemistry 2008 Volume 2008( Issue 7) pp:1135-1140
Publication Date(Web):
DOI:10.1002/ejic.200701105
Abstract
Reaction of (R)-bis(pyrrol-2-ylmethyleneamino)-1,1′-binaphthyl (1H2) or (R)-N,N′-bis(pyridin-2-ylmethyl)-1,1′-binaphthyl-2,2′-diamine (2H2) with Zr(NMe2)4 (1 equiv.) gives chiral zirconium amides 1-Zr(NMe2)2·C7H8 (4·C7H8) or 2-Zr(NMe2)2 (6) in good yields, respectively. Under similar conditions, 1H2 reacts with Ti(NMe2)4 (1 equiv.) to give chiral titanium amide 1-Ti(NMe2)2·C6H6 (3·C6H6), whereas treatment of 2H2 with Ti(NMe2)4 (1 equiv.) leads to the isolation of bis(ligated) product (2)2-Ti·C7H8 (5·C7H8) in 74 % yield. All complexes were characterized by various spectroscopic techniques, elemental analysis, and X-ray diffraction analysis. Zirconium amides 4 and 6 are active catalysts for the asymmetric hydroamination/cyclization of aminoalkenes, and cyclic amines were obtained in good-to-excellent yields with moderate ee values (up to 59 %); titanium amides 2 and 5 were not active under the reaction conditions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Co-reporter:Yadong Zhang, Li Xiang, Qiuwen Wang, Xin-Fang Duan, Guofu Zi
Inorganica Chimica Acta 2008 Volume 361(Issue 5) pp:1246-1254
Publication Date(Web):1 April 2008
DOI:10.1016/j.ica.2007.08.003
Condensation of (S,S)-1,2-cyclohexanediamine with 2 equiv. of 2-pyridine carboxaldehyde in toluene in the presence of molecular sieves at 70 °C gives N,N′-bis(pyridin-2-ylmethylene)-(S,S)-1,2-cyclohexanediamine (S,S-1) in 95% yield. Reduction of 1 with an excess of NaBH4 in MeOH at 50 °C gives N,N′-bis(pyridin-2-ylmethyl)-(S,S)-1,2-cyclohexanediamine (S,S-2) in 90% yield. Reaction of 1 or 2 with 1 equiv. of CuCl2 · 2H2O in methanol gives complexes [N-(pyridin-2-ylmethylene)-(S,S)-1,2-cyclohexanediamine]CuCl2 (3) and [Cu(S,S-2)(H2O)]Cl2 · H2O (4), respectively, in good yields. Complex 4 can further react with 1 equiv. of CuCl2 · 2H2O in methanol to give [Cu(S,S-2)][CuCl4] (5) in 75% yield. The rigidity of the ligand coupled with the steric effect of the free anion plays an important role in the formation of the helicates. Treatment of ligand S,S-1 with AgNO3 induces a polymer helicate {[Ag(S,S-1)][NO3]}n (6), while reaction of ligand 2 with AgPF6 or AgNO3 in methanol affords a mononuclear single helicate [Ag(S,S-2)][PF6] (7) or a dinuclear double helicate [Ag2(S,S-2)2][NO3]2 · 2CH3OH (8) in good yields, respectively. All compounds have been characterized by various spectroscopic data and elemental analyses. Compounds 1, 3–5, 7 and 8 have been further subjected to single-crystal X-ray diffraction analyses. The Cu(II) complexes do not show catalytic activity for allylation reaction, in contrast to Ag(I) complexes, but they do show catalytic activity for Henry reaction (nitroaldol reaction) that Ag(I) complexes do not.A series of chiral Cu(II) and Ag(I) complexes have been prepared. The Cu(II) complexes do not show catalytic activity for allylation reaction, in contrast to Ag(I) complexes, but they do show catalytic activity for Henry reaction (nitroaldol reaction) that Ag(I) complexes do not.
Co-reporter:Ruochen Liu;Xuemei Bai;Zhanbin Zhang
Applied Organometallic Chemistry 2008 Volume 22( Issue 12) pp:671-675
Publication Date(Web):
DOI:10.1002/aoc.1457
Abstract
A new series of chiral 3-hydroxyazetidines has been prepared from (S)-1-(4-methoxyphenyl)ethylamine. These ligands have shown excellent catalytic activities and enantiomeric selectivities in asymmetric addition of diethylzinc to aromatic aldehydes. Copyright © 2008 John Wiley & Sons, Ltd.
Co-reporter:Guofu Zi, Li Xiang and Haibin Song
Organometallics 2008 Volume 27(Issue 6) pp:1242-1246
Publication Date(Web):February 28, 2008
DOI:10.1021/om701058k
A new series of bis-ligated organolanthanide amides, (1)2-LnN(SiMe3)2·C7H8 (Ln = Sm (2), Y (3), Yb (4)), have been prepared by the reaction of Ln[N(SiMe3)2]3 with the ligand (S)-2-(pyrrol-2-ylmethyleneamino)-2′-(dimethylamino)-1,1′-binaphthyl (1H) in good yields. They are active catalysts for the asymmetric hydroamination/cyclization reaction of aminoalkenes, affording cyclic amines in moderate to good conversions with moderate to good ee values.
Co-reporter:Guofu Zi;Li Xiang;Yadong Zhang;Qiuwen Wang;Zhanbin Zhang
Applied Organometallic Chemistry 2007 Volume 21(Issue 3) pp:
Publication Date(Web):30 JAN 2007
DOI:10.1002/aoc.1197
(PhCH2NH2)2CuCl2 (2), an effective oxidation reagent for oxidative coupling of 2-naphthylamine (1) to form 2,2′-diamino-1,1′-binaphthyl (4), is studied. Oxidative coupling of 2-naphthylamine (1) is carried out at room temperature in methanol by (PhCH2NH2)2CuCl2 (2), which is prepared from CuCl2·2H2O and benzylamine in methanol, to give a novel copper complex, [{1,1′-(C10H6)2-2,2′-(NH2)2}2CuCl]Cl·CH3OH·3H2O (3), in good yield. Treatment of 3 with aqueous HCl (37%), followed by addition of NH3·H2O (25%), gives 2,2′-diamino-1,1′-binaphthyl (4) in a moderate yield (total yield from 1: > 70%). Both 2 and 3 have been characterized by various techniques, such as infrared spectroscopy, elemental analyses and X-ray diffraction. Copyright © 2007 John Wiley & Sons, Ltd.
Co-reporter:Min Li;Zhanbin Zhang
Chirality 2007 Volume 19(Issue 10) pp:802-808
Publication Date(Web):22 AUG 2007
DOI:10.1002/chir.20470
A new series of chiral cis-3-hydroxyazetidines have been prepared from (R)-1-phenylethylamine. They have excellent catalytic activities and enantiomeric selectivities in asymmetric addition of diethylzinc to aromatic aldehydes. Chirality, 2007. © 2007 Wiley-Liss, Inc.
Co-reporter:Wenshan Ren, Wayne W. Lukens, Guofu Zi, Laurent Maron and Marc D. Walter
Chemical Science (2010-Present) 2013 - vol. 4(Issue 3) pp:NaN1174-1174
Publication Date(Web):2013/01/10
DOI:10.1039/C2SC22013J
Bipyridyl thorium metallocenes [η5-1,2,4-(Me3C)3C5H2]2Th(bipy) (1) and [η5-1,3-(Me3C)2C5H3]2Th(bipy) (2) have been investigated by magnetic susceptibility and computational studies. The magnetic susceptibility data reveal that 1 and 2 are not diamagnetic, but they behave as temperature independent paramagnets (TIPs). To rationalize this observation, density functional theory (DFT) and complete active space self-consistent field (CASSCF) calculations have been undertaken, which indicated that Cp′2Th(bipy) has indeed a Th(IV)(bipy2−) ground state (f0d0π*2, S = 0), but the open-shell singlet (f0d1π*1, S = 0) (almost degenerate with its triplet congener) is only 9.2 kcal mol−1 higher in energy. Complexes 1 and 2 react cleanly with Ph2CS to give [η5-1,2,4-(Me3C)3C5H2]2Th[(bipy)(SCPh2)] (3) and [η5-1,3-(Me3C)2C5H3]2Th[(bipy)(SCPh2)] (4), respectively, in quantitative conversions. Since no intermediates were observed experimentally, this reaction was also studied computationally. Whereas coordination of Ph2CS to 2 in its S = 0 ground state is not possible, Ph2CS can coordinate to 2 in its triplet state (S = 1) upon which a single electron transfer (SET) from the (bipy2−) fragment to Ph2CS followed by C–C coupling takes place.
Co-reporter:Guofu Zi
Dalton Transactions 2009(Issue 42) pp:NaN9109-9109
Publication Date(Web):2009/07/22
DOI:10.1039/B906588A
The development of catalysts for intramolecular asymmetric alkene hydroamination has been investigated extensively over the past two decades, since the hydroamination is a highly atom economical process in which an amine N–H bond is added to an unsaturated carbon–carbon bond leading to the formation of nitrogen heterocycles that are building blocks in numerous biologically and pharmacologically active compounds. The organolanthanide catalysts have been shown to be promising in this area. This perspective highlights the recent progress in the development of organolanthanide catalysts with chiral biaryl-backbones for the asymmetric hydroamination/cyclization of non-activated alkenes.
Co-reporter:Guofu Zi, Qiuwen Wang, Li Xiang and Haibin Song
Dalton Transactions 2008(Issue 43) pp:NaN5944-5944
Publication Date(Web):2008/09/16
DOI:10.1039/B808238C
A new series of lanthanide and group 4 metal complexes have been prepared from the reactions between Ln[N(SiMe3)2]3 or M(NMe2)4 and chiral ligands, (R)-2-(pyrrol-2-ylmethyleneamino)-2′-methoxy-1,1′-binaphthyl (1H), (S)-5,5′,6,6′,7,7′,8,8′-octahydro-2-(pyrrol-2-ylmethyleneamino)-2′-methoxy-1,1′-binaphthyl (2H) and (R)-2-(pyrrol-2-ylmethyleneamino)-2′-methoxy-6,6′-dimethyl-1,1′-biphenyl (3H). The steric effect of the ligand coupled with the size effect of the ions plays an important role in the formation of the lanthanide complexes. For example, treatment of 1H with 1 equiv of Ln[N(SiMe3)2]3 (Ln = Y, Yb) in toluene gives the tris-ligated complexes, (1)3Y·C7H8 (5·C7H8) and (1)3Yb·2C7H8 (6·2C7H8) in good yields; reaction of 2H with 1 equiv of Sm[N(SiMe3)2]3 also gives the tris-ligated product (2)3Sm (7), while treatment of 2H with 1 equiv of Ln[N(SiMe3)2]3 (Ln = Y, Yb) leads to the isolation of the bis-ligated organolanthanide amides (2)2LnN(SiMe3)2·2C6H6 (Ln = Y (8·2C6H6), Yb (9·2C6H6)) in good yields. Reaction of 1H, 2H or 3H with 1 equiv of M(NMe2)4 gives, after recrystallization from a toluene or benzene solution, the chiral bis-ligated titanium amides (1)2Ti(NMe2)2·0.75C7H8 (10·0.75C7H8), (2)2Ti(NMe2)2 (12), (3)2Ti(NMe2)2·C6H6 (14·C6H6), and zirconium amides (1)2Zr(NMe2)2·C7H8 (11·C7H8), (2)2Zr(NMe2)2 (13), (3)2Zr(NMe2)2·C6H6 (15·C6H6), in good yields, respectively. Treatment of Zr(NMe2)4 with 1 equiv of (R)-2-(pyrrol-2-ylmethylamino)-2′-methoxy-1,1′-binaphthyl (4H2), which was prepared from the reduction of 1H with an excess of NaBH4 in a solvent mixture of MeOH and toluene (1:1) at 50 °C, gives the trinuclear complex [(R)-2-O-C20H12-2′-(NCH2C4H3)]2Zr3(NMe2)6·2C7H8 (16·2C7H8) in 65% yield. Organolanthanide amides and zirconium amides are active catalysts for asymmetric hydroamination/cyclization of aminoalkenes, affording cyclic amines in moderate to good yields with moderate ee values, while the titanium amides are not. During the course of the catalytic reaction, 8 is decomposed leading to the isolation of (2)3Y·C7H8 (17·C7H8) in 35% yield from a toluene solution. The organolanthanide amides are also active catalysts for ring-opening polymerization of rac-lactide, giving isotactic-rich polylactides. All compounds have been characterized by various spectroscopic techniques, and elemental analyses. The solid-state structures of compounds 2H, 3H, 5–11, and 13–17 have further been confirmed by X-ray diffraction analyses.
Co-reporter:Guofu Zi, Furen Zhang and Haibin Song
Chemical Communications 2010 - vol. 46(Issue 34) pp:NaN6298-6298
Publication Date(Web):2010/07/29
DOI:10.1039/C0CC01265C
A highly enantioselective group 5 metal amide catalyst system is reported for the hydroaminoalkylation of secondary amines to give chiral amines in good yields with excellent ee values (up to 93%) by loading of 5% precatalyst.
Co-reporter:Furen Zhang, Haibin Song and Guofu Zi
Dalton Transactions 2011 - vol. 40(Issue 7) pp:NaN1566-1566
Publication Date(Web):2011/01/10
DOI:10.1039/C0DT01229G
A new series of group 5 metal amides have been prepared from the reaction between V(NMe2)4 or M(NMe2)5 (M = Nb, Ta) and chiral ligands, (R)-2,2′-bis(mesitoylamino)-1,1′-binaphthyl (1H2), (R)-5,5′,6,6′,7,7′,8,8′-octahydro-2,2′-bis(mesitoylamino)-1,1′-binaphthyl (2H2), (R)-6,6′-dimethyl-2,2′-bis(mesitoylamino)-1,1′-biphenyl (3H2), (R)-2,2′-bis(mesitylenesulfonylamino)-6,6′-dimethyl-1,1′-biphenyl (4H2), (R)-2,2′-bis(diphenylthiophosphoramino)-1,1′-binaphthyl (5H2), (R)-2,2′-bis[(3-tert-butyl-2-hydroxybenzylidene)amino]-6,6′-dimethyl-1,1′-biphenyl (6H2), (R)-2,2′-bis[(3,5-di-tert-butyl-2-hydroxybenzylidene)amino]-6,6′-dimethyl-1,1′-biphenyl (7H2), (R)-2,2′-bis[(3-tert-butyl-2-hydroxybenzylidene)amino]-1,1′-binaphthyl (8H2), (S)-2-(mesitoylamino)-2′-(dimethylamino)-1,1′-binaphthyl (9H), and (R)-2-(mesitoylamino)-2′-(dimethylamino)-6,6′-dimethyl-1,1′-biphenyl (10H), which are derived from (R) or (S)-2,2′-diamino-1,1′-binaphthyl, and (R)-2,2′-diamino-6,6′-dimethyl-1,1′-biphenyl, respectively. Treatment of V(NMe2)4 or M(NMe2)5 (M = Nb, Ta) with 1 equiv of C2-symmetric amidate ligands 1H2, 2H2, 3H2, 4H2, and 5H2, or Schiff base ligands 6H2, 7H2 and 8H2 at room temperature gives, after recrystallization from a benzene, toluene or n-hexane solution, the vanadium amides (1)V(NMe2)2 (11), (2)V(NMe2)2 (14), (3)V(NMe2)2 (17), (5)V(NMe2)2 (22), (6)V(NMe2)2 (23) and (7)V(NMe2)2 (24), and niobium amides (1)Nb(NMe2)3 (12), (2)Nb(NMe2)3 (15), (3)Nb(NMe2)3 (18), (4)Nb(NMe2)3 (20) and [2-(3-Me3C-2-O-C6H3CHN)-2′-(N)-C20H12][2-(Me2N)2CH-6-CMe3-C6H3O]NbNMe2·C7H8 (25·C7H8), and tantalum amides (1)Ta(NMe2)3 (13), (2)Ta(NMe2)3 (16), (3)Ta(NMe2)3 (19) and (4)Ta(NMe2)3 (21) respectively, in good yields. Reaction of V(NMe2)4 or M(NMe2)5 (M = Nb, Ta) with 2 equiv of C1-symmetric amidate ligands 9H or 10H at room temperature gives, after recrystallization from a toluene or n-hexane solution, the chiral bis-ligated vanadium amides (9)2V(NMe2)2·3C7H8 (27·3C7H8) and (10)V(NMe2)2 (28), and chiral bis-ligated metallaaziridine complexes (10)2M(NMe2)(η2-CH2NMe) (M = Nb (29), Ta (30)) respectively, in good yields. The niobium and tantalum amidate complexes are stable in a toluene solution at or below 160 °C, while the vanadium amidate complexes degrade viadiemthylamino group elimination at this temperature. For example, heating the complex (2)V(NMe2)2 (14) in toluene at 160 °C for four days leads to the isolation of the complex [(2)V]2(μ-NMe2)2 (26) in 58% yield. These new complexes have been characterized by various spectroscopic techniques, and elemental analyses. The solid-state structures of complexes 12, 13, and 15–30 have further been confirmed by X-ray diffraction analyses. The vanadium amides are active chiral catalysts for the asymmetric hydroamination/cyclization of aminoalkenes, affording cyclic amines in moderate to good yields with good ee values (up to 80%), and the tantalum amides are outstanding chiral catalysts for the hydroaminoalkylation, giving chiral secondary amines in good yields with excellent ee values (up to 93%).
Co-reporter:Ann Christin Fecker, Matthias Freytag, Peter G. Jones, Ning Zhao, Guofu Zi and Marc D. Walter
Dalton Transactions 2015 - vol. 44(Issue 37) pp:NaN16331-16331
Publication Date(Web):2015/08/24
DOI:10.1039/C5DT02851E
The synthesis of C2 symmetric enantiomerically pure open Ca and Sr metallocenes, [(η5-pdl*)2Ca(thf)] (1) and [(η5-pdl*)2Sr(thf)2] (2) (pdl* = dimethylnopadienyl) is described and these complexes were fully characterized. The solid state structures confirm that the pdl* ligands coordinate exclusively with the less sterically demanding site to the Ca and Sr atoms. These complexes are active catalysts for the controlled ring opening polymerization (ROP) of rac-lactide to give heterotactically enriched polylactides (PL) with narrow polydispersities (PDI = 1.29–1.31) and without adding further activators.
Co-reporter:Wenshan Ren, Xuebin Deng, Guofu Zi and De-Cai Fang
Dalton Transactions 2011 - vol. 40(Issue 38) pp:NaN9664-9664
Publication Date(Web):2011/08/04
DOI:10.1039/C1DT11149C
The first thorium poly-carbene complexes [(Ph2PS)2C]2Th(DME) (2) and [{[(Ph2PS)2C]3Th}Li2(DME)]n (3) have been prepared and structurally characterized. DFT calculations reveal that the ThC bond is polarized toward the nucleophilic carbene carbon atom, which is further verified by the experimental observation that the ThC bond shows a nucleophilic behavior with Ph2CO.
Co-reporter:Guofu Zi, Furen Zhang, Li Xiang, Yue Chen, Weihai Fang and Haibin Song
Dalton Transactions 2010 - vol. 39(Issue 17) pp:NaN4061-4061
Publication Date(Web):2010/02/23
DOI:10.1039/B923457H
A new series of titanium(IV) and zirconium(IV) amides have been prepared from the reaction between M(NMe2)4 (M = Ti, Zr) and chiral ligands, (R)-2,2′-bis(p-toluenesulfonylamino)-1,1′-binaphthyl (1H2), (R)-2,2′-bis(diphenylphosphinoylamino)-1,1′-binaphthyl (2H2), (R)-2,2′-bis(mesitoylamino)-1,1′-binaphthyl (3H2), (R)-5,5′,6,6′,7,7′,8,8′-octahydro-2,2′-bis(pyrrol-2-ylmethyleneamino)-1,1′-binaphthyl (4H2), (R)-5,5′,6,6′,7,7′,8,8′-octahydro-2,2′-bis(mesitoylamino)-1,1′-binaphthyl (5H2), and (R)-5,5′,6,6′,7,7′,8,8′-octahydro-2,2′-bis(mesitylenesulfonylamino)-1,1′-binaphthyl (6H2), which are derived from (R)-2,2′-diamino-1,1′-binaphthyl. Reaction of M(NMe2)4 with 1 equiv of arylsulfonylamides 1H2 and 6H2, diphenylphosphoramide 2H2, mesitoylamides 3H2 and 5H2, or Schiff base ligand 4H2 at room temperature gives, after recrystallization from a benzene, toluene or n-hexane solution, the chiral titanium amides (1)Ti(NMe2)2·3C6H6 (7·3C6H6), (4)Ti(NMe2)2 (11), (5)Ti(NMe2)2 (13) and (6)Ti(NMe2)2 (15), and zirconium amides (1)Zr(NMe2)2 (8), (2)Zr(NMe2)2 (9), (3)Zr(NMe2)2 (10), (4)Zr(NMe2)2 (12), (5)Zr(NMe2)2 (14) and (6)Zr(NMe2)2·C7H8 (16·C7H8) respectively, in good yields. These amides are stable below 90 °C in toluene solution, but they degrade via ligand redistribution at a higher temperature. For example, treatment of (1)Zr(NMe2)2 (8) or (5)Zr(NMe2)2 (14) in refluxing toluene for three days leads to the isolation of the complexes (1)2Zr·C7H8 (17·C7H8) and (5)2Zr·3C7H8 (18·3C7H8) respectively, in moderate yields. These new compounds have been characterized by various spectroscopic techniques, and elemental analyses. The solid-state structures of compounds 7–9, 11–13, and 15–18 have further been confirmed by X-ray diffraction analyses. The titanium amide 13 and all the zirconium amides are active catalysts for the asymmetric hydroamination/cyclization of aminoalkenes, affording cyclic amines in moderate to excellent yields with moderate to excellent ee values (up to 93%). Theoretical studies reveal the interaction between the carbon chain of the substrate and the sterically demanding ligand groups plays a key role in the stereodirection of the enantioselection during the ZrN bond approaches to the CC bond.
Co-reporter:Dao Zhang and Guofu Zi
Chemical Society Reviews 2015 - vol. 44(Issue 7) pp:NaN1921-1921
Publication Date(Web):2015/01/22
DOI:10.1039/C4CS00441H
Since the discovery of a stable N-heterocyclic carbene (NHC), the use of NHCs in chemistry has developed rapidly over the past two decades. These interesting compounds are predominantly employed in organometallic chemistry as ligands for various metal centers, and as organocatalysts for a variety of transformations. In particular, the NHC transition metal complexes have received widespread attention, and significant progress has been made in the development of group 4 NHC-complexes in the last few years. These group 4 NHC-complexes are of interest because of their unique structural properties, and their potential application in organic transformations and catalysis. This review covers the superior design strategies for NHC ligands to stabilize early transition metals and well-defined group 4 metal complexes with mono- and multi-dentate NHC ligands. In this context, four types of NHC-complexes, i.e., carbon-functionalized NHCs, nitrogen-functionalized NHCs, oxygen-functionalized NHCs and nitrogen/oxygen-functionalized unsymmetric NHCs, are described. In addition, the use of group 4 NHC-complexes as catalysts in olefin (co)polymerization, ring-opening polymerization of rac-lactide, copolymerization of epoxides and CO2, as well as hydroamination/cyclization of aminoalkenes, is presented. Furthermore, limitations and challenges are discussed.
Co-reporter:Wenshan Ren, Haibin Song, Guofu Zi and Marc D. Walter
Dalton Transactions 2012 - vol. 41(Issue 19) pp:NaN5973-5973
Publication Date(Web):2012/03/30
DOI:10.1039/C2DT00051B
The synthesis, structure and reactivity of a new bipy thorium metallocene have been studied. The reduction of the thorium chloride metallocene [η5-1,3-(Me3C)2C5H3]2ThCl2 (1) with potassium graphite in the presence of 2,2′-bipyridine gives the purple bipy metallocene [η5-1,3-(Me3C)2C5H3]2Th(bipy) (2) in good yield. Complex 2 has been fully characterized by various spectroscopic techniques, elemental analysis and X-ray diffraction analysis. Complex 2 reacts cleanly with trityl chloride, silver halides and diphenyl diselenide, leading to the halide metallocenes [η5-1,3-(Me3C)2C5H3]2ThX2 (X = Cl (1), Br (3), I (4)) and [η5-1,3-(Me3C)2C5H3]2Th(F)(μ-F)3Th[η5-1,3-(Me3C)2C5H3](F)(bipy) (5), and selenido metallocene [η5-1,3-(Me3C)2C5H3]2Th(SePh)2 (6), in good conversions. In addition, 2 cleaves the CS bond of CS2 to give the sulfido complex, [η5-1,3-(Me3C)2C5H3]2ThS (7), which further undergoes an irreversible dimerization or nucleophilic addition with CS2, leading to the dimeric sulfido complex {[η5-1,3-(Me3C)2C5H3]2Th}(μ-S)2 (8) and dimeric trithiocarbonate complex {[η5-1,3-(Me3C)2C5H3]2Th}(μ-CS3)2 (10) in good yields, respectively.
Co-reporter:Lei Zhang, Guohua Hou, Guofu Zi, Wanjian Ding and Marc D. Walter
Dalton Transactions 2017 - vol. 46(Issue 11) pp:NaN3728-3728
Publication Date(Web):2017/03/06
DOI:10.1039/C7DT00396J
The uranium metallacyclocumulene, [η5-1,3-(Me3C)2C5H3]2U(η4-C4Ph2) (2) was isolated by the reduction of [η5-1,3-(Me3C)2C5H3]2UCl2 (1) with potassium graphite (KC8) in the presence of 1,4-diphenylbutadiyne (PhCC–CCPh) in good yield. Furthermore it was fully characterized including the determination of its molecular structure; and the reactivity of 2 towards various small unsaturated organic molecules was explored. For example, while complex 2 shows no reactivity with alkynes and 2,2′-bipyridine (bipy), it reacts as a nucleophile when exposed to carbodiimides, diazabutadienes, isothiocyanates, ketones, and pyridine derivatives, leading to five-, seven- or nine-membered heterometallacycles. In contrast, treatment of complex 2 with CS2 results in CS bond cleavage and forms the binuclear complex [η5-1,3-(Me3C)2C5H3]2U[μ-η4:η3-PhCCC(S)C(Ph)CS]U[η5-1,3-(Me3C)2C5H3]2 (10). Density functional theory (DFT) studies complement the experimental study.
Co-reporter:Ning Zhao, Guohua Hou, Xuebin Deng, Guofu Zi and Marc D. Walter
Dalton Transactions 2014 - vol. 43(Issue 22) pp:NaN8272-8272
Publication Date(Web):2014/03/07
DOI:10.1039/C4DT00510D
Chiral group 4 NHC–metal complexes were prepared in good yields by amine elimination from M(NR2)4 (M = Ti, Zr, Hf; R = Me, Et) and chiral pincer NHC-ligands, L4 (L4a and L4b), L5 and L6, which are derived from (S,S)-diphenyl-1,2-ethanediamine. Treatment of M(NR2)4 with 1 equiv. of L4 in THF gives, after recrystallization from a benzene solution, the chiral titanium amides (L4)Ti(NMe2)(Br)(THF) (7) and (L4)Ti(NMe2)(Cl)(THF) (11), zirconium amides (L4)Zr(NMe2)(Br)(THF) (8), (L4)Zr(NEt2)(Br)(THF) (10), (L4)Zr(NMe2)(Cl)(THF) (12) and (L4)Zr(NEt2)(Cl)(THF) (14), and hafnium amides (L4)Hf(NMe2)(Br)(THF) (9) and (L4)Hf(NMe2)(Cl)(THF) (13), respectively. Similarly, the reactions of L5 or L6 with 1 equiv. of M(NR2)4 yield the titanium amide (L6)Ti(NMe2)(Cl)(THF) (16), the zirconium amides (L5)Zr(NMe2)(Cl)(THF) (15), (L6)Zr(NMe2)(Cl)(THF) (17) and (L6)Zr(NEt2)(Cl)(THF) (19), and the hafnium amide (L6)Hf(NMe2)(Cl)(THF) (18), respectively. Complexes 7–19 were characterized by various spectroscopic techniques and elemental analyses. The molecular structures of 10 and 14–19 were also established by X-ray diffraction analyses, which represent the first example of the structurally characterized group 4 chiral NHC–metal complex. Furthermore, 7–19 are active catalysts for the polymerization of rac-lactide in the presence of isopropanol, leading to the heterotactic-rich polylactides.
![BENZENE, 1-[(1S)-1-METHYL-2-NITROETHYL]-4-(2-METHYLPROPYL)-](http://img.cochemist.com/ccimg/848800/848731-68-0.png)
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![Benzene,1-methoxy-4-[(1S)-1-methyl-2-nitroethyl]-](http://img.cochemist.com/ccimg/748200/748183-59-7.png)
![Benzene,1-methoxy-4-[(1S)-1-methyl-2-nitroethyl]-](http://img.cochemist.com/ccimg/748200/748183-59-7_b.png)
![BENZENE, [(1S)-1-METHYL-2-NITROETHYL]-](http://img.cochemist.com/ccimg/746700/746647-15-4.png)
![BENZENE, [(1S)-1-METHYL-2-NITROETHYL]-](http://img.cochemist.com/ccimg/746700/746647-15-4_b.png)
![Benzene, 1-methoxy-4-[(1E)-1-methyl-2-nitroethenyl]-](http://img.cochemist.com/ccimg/615600/615552-91-5.png)
![Benzene, 1-methoxy-4-[(1E)-1-methyl-2-nitroethenyl]-](http://img.cochemist.com/ccimg/615600/615552-91-5_b.png)
![Benzene, [(1S)-1-(nitromethyl)propyl]-](http://img.cochemist.com/ccimg/167500/167422-36-8.png)
![Benzene, [(1S)-1-(nitromethyl)propyl]-](http://img.cochemist.com/ccimg/167500/167422-36-8_b.png)
![2-[1-(3,3-DIMETHYLCYCLOHEXYL)ETHOXY]-2-OXOETHYL PROPIONATE](http://img.cochemist.com/ccimg/30700/30616-73-0.png)
![2-[1-(3,3-DIMETHYLCYCLOHEXYL)ETHOXY]-2-OXOETHYL PROPIONATE](http://img.cochemist.com/ccimg/30700/30616-73-0_b.png)
![Benzene, [(1E)-1-methyl-2-nitroethenyl]-](/data/chemimg/1737100/15241-24-4.png)
![Benzene, [(1E)-1-methyl-2-nitroethenyl]-](/data/chemimg/1737100/15241-24-4_b.png)
![Thorium,dichlorobis[(1,2,3,4,5-h)-1,2,3,4,5-pentamethyl-2,4-cyclopentadien-1-yl]-](http://img.cochemist.com/ccimg/67600/67506-88-1.png)
![Thorium,dichlorobis[(1,2,3,4,5-h)-1,2,3,4,5-pentamethyl-2,4-cyclopentadien-1-yl]-](http://img.cochemist.com/ccimg/67600/67506-88-1_b.png)
