Metal-metal bonded dinuclear and organodimetallic complexes of the early transition metals (Groups 4 and 5): synthesis, structure, and reactivity

Messerle, Louis

doi:10.1021/cr00089a012

Cited by 52 publications

(25 citation statements)

References 61 publications

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“…Although the Ta(1) À TaA C H T U N G T R E N N U N G (1_2) distance is in the single-bond range, a double bond would be expected for B 2 H 6 2À bonded to a [(Cp*Ta III ) 2 ] 4 + fragment. MetalÀmetal bond-length order is not very reliable in complexes having bridging ligands and MÀM bonds lengthen substantially upon substitution of a m-hydride by a mhalide [21,36,37] or B 2 H 6 2À ligand. [21] Comparison of the structures of 1-3: Compounds 1-3 have the same ligand sets (two B 2 H 6 groups), so a structural comparison with Re, Mo, and W analogues can be made (Table 1).…”

Section: Characterization Of 1-3mentioning

confidence: 99%

Fine Tuning of Metallaborane Geometries: Chemistry of Metallaboranes of Early Transition Metals Derived from Metal Halides and Monoborane Reagents

Bose

Geetharani

Ramkumar

et al. 2009

Chemistry A European J

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Reaction of [Cp(n)MCl(4-x)] (M=V: n=x=2; M=Nb: n=1, x=0) or [Cp*TaCl(4)] (Cp=eta(5)-C(5)H(5), Cp*=eta(5)-C(5)Me(5)), with [LiBH(4).thf] at -70 degrees C followed by thermolysis at 85 degrees C in the presence of [BH(3).thf] yielded the hydrogen-rich metallaboranes [(CpM)(2)(B(2)H(6))(2)] (1: M=V; 2: M=Nb) and [(Cp*Ta)(2)(B(2)H(6))(2)] (3) in modest to high yields. Complexes 1 and 3 are the first structurally characterized compounds with a metal-metal bond bridged by two hexahydroborate (B(2)H(6)) groups forming a symmetrical complex. Addition of [BH(3).thf] to 3 results in formation of a metallaborane [(Cp*Ta)(2)B(4)H(8)(mu-BH(4))] (4) containing a tetrahydroborate ligand, [BH(4)](-), bound exo to the bicapped tetrahedral cage [(Cp*Ta)(2)B(4)H(8)] by two Ta-H-B bridge bonds. The interesting structural feature of 4 is the coordination of the bridging tetrahydroborate group, which has two B-H bonds coordinated to the tantalum atoms. All these new metallaboranes have been characterized by mass, (1)H, (11)B, and (13)C NMR spectroscopy and elemental analysis and the structural types were established unequivocally by crystallographic analysis of 1-4.

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Section: Characterization Of 1-3mentioning

confidence: 99%

Fine Tuning of Metallaborane Geometries: Chemistry of Metallaboranes of Early Transition Metals Derived from Metal Halides and Monoborane Reagents

Bose

Geetharani

Ramkumar

et al. 2009

Chemistry A European J

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“…530 In addition, a review covering organometallic dinuclear complexes, including metal-metalbonded species, encompasses several monokis(cyclopentadienyl) niobium and tantalum species. 531 The chemistry of monokis(cyclopentadienyl) niobium and tantalum complexes developed after that of their bis(cyclopentadienyl) analogues since a convenient entry into (T|-C 5 R 5 )MX 4 directly f r o m the pentahalides was uncovered later. Typically, tin-99 ' 198 ' 488 or silicon-cyclopentadienyl reagents are required for the selective substitution of one cyclopentadienyl ligand at MX 5 to form (r|-C 5 R 5 )MX 4 .…”

Section: (I) Halide Complexesmentioning

confidence: 99%

Niobium and Tantalum

Wigley

Gray

1995

Comprehensive Organometallic Chemistry II

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“…[54,55] We used 1,4-diazadiene (DAD) and 1-azadiene (AD) as nitrogen li- (32) [56,57] with the corresponding AD ligands. [49,50] Benzylation of the dichloro complexes 31 gave several interesting tantalum complexes having the AD ligand, depending on the reaction conditions, i.e., stoichiometry and solvent.…”

Section: Benzylidene Complexes Of Tantalum With 14-diazadiene or 1-amentioning

confidence: 99%

Ligand Architecture on Stereocontrol of Half‐Metallocene Benzylidene Complexes of Tantalum

Mashima

2005

Adv Synth Catal

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Dedicated to Professor R. R. Schrock for his distinguished and continuous contributions to inorganic and organometallic chemistry.Abstract: This brief review discloses our studies on half-metallocene benzylidene complexes of tantalum bearing 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, oxylylene, 1,4-diaryl-1,4-diaza-1,3-butadiene, or 1-aryl-4-phenyl-1-aza-1,3-butadiene as an auxiliary ligand. These auxiliary ligands can control the stereochemistry of the benzylidene moiety and induce intriguing reactivity. Furthermore, the butadiene and o-xylylene complexes catalyze ring opening metathesis polymerization of norbornene to respectively give polymers with cisand trans-C ¼ C bonds. Such selectivity can be attributed to control of the stereochemistry of the propagating alkylidene chain end by the auxiliary ligand: the butadiene complex favors the anti-rotamer while the o-xylylene complex favors the syn-one.

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Metal-metal bonded dinuclear and organodimetallic complexes of the early transition metals (Groups 4 and 5): synthesis, structure, and reactivity

Cited by 52 publications

References 61 publications

Fine Tuning of Metallaborane Geometries: Chemistry of Metallaboranes of Early Transition Metals Derived from Metal Halides and Monoborane Reagents

Fine Tuning of Metallaborane Geometries: Chemistry of Metallaboranes of Early Transition Metals Derived from Metal Halides and Monoborane Reagents

Niobium and Tantalum

Ligand Architecture on Stereocontrol of Half‐Metallocene Benzylidene Complexes of Tantalum

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