Structure and Reactivity of Mono(cyclopentadienyl)vanadium Alkynyl and Aryne Complexes

Buijink, Jkf; Kloetstra, K. R.; Meetsma, Auke; Teuben, Jan H.; Smeets, W. J. J.; Spek, Anthony L.

doi:10.1021/om950902m

Cited by 42 publications

(42 citation statements)

References 81 publications

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“…It is noteworthy that both αand β-hydrogen elimination decomposition processes operate in hydrocarbyl derivatives of the CpV III (Cp = η-C 5 H 5 ) fragment. 29,30 Given that [(Me 3 Si) 2 N] 2 VER [E = Se or Te; R = Si(SiMe 3 ) 3 or SiPh 3 ] 1 have pseudo-five-co-ordinate vanadium centers when apical C᎐H agostic interactions are taken into account, it is not inconceivable that species such as [(Me 3 -Si) 2 N] 2 VEt(L) may decompose by αor β-hydrogen elimination to unstable intermediates even without prior dissociation of the L ligand.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of N(SiMe3)2 supported vanadium(III) complexes, including hydrocarbyl, tetrahydroborate and azaalkenylidene derivatives †

Gerlach¹,

Arnold²

1997

J. Chem. Soc., Dalton Trans.

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Reaction of [(Me 3 Si) 2 N] 2 VCl(THF) (THF = tetrahydrofuran) with MgMe 2 or LiMe afforded [(Me 3 Si) 2 N] 2 -VMe(THF) in 70% yield. Nitrogen donors displaced THF in these V III species, and [(Me 3 Si) 2 N] 2 VCl(lut) (lut = 3,5-dimethylpyridine) and [(Me 3 Si) 2 N] 2 VMe(pyr) (pyr = pyridine) were isolated and characterized. Solution thermolysis of [(Me 3 Si) 2 N] 2 VMe(THF) yielded the known V III dimer {[(Me 3 Si) 2 N]V(µ-CH 2 SiMe 2 -NSiMe 3 )} 2 in 73% yield. Reaction of [(Me 3 Si) 2 N] 2 VMe(THF) with 3 equivalents of RNC (R = Bu t or Xyl; Xyl = 2,6-dimethylphenyl) gave diazavanadacycles of empirical formulae [features an exocyclic keteneamine functionality; for R = Xyl, an additional C᎐C bond forming step results in slightly more complex connectivity, to give. The crystal structures of both compounds are presented. Alkylation of [(Me 3 Si) 2 N] 2 VCl(THF) with 2-thienyllithium led to isolation of [(Me 3 Si) 2 N] 2 V(2-C 4 H 3 S)(THF) (60%). A blue solution that acted as a source of '[(Me 3 Si) 2 N] 2 VPh' was obtained from the reaction of 0.5 equivalent of MgPh 2 with [(Me 3 Si) 2 N] 2 VCl(THF). The addition of pyr or PhCN to the blue mixture gave [(Me 3 Si) 2 N] 2 VPh(pyr) (60%) and [(Me 3 Si) 2 N] 2 V(NCPh 2 )(NCPh) (66%), respectively. The chelated aryl amine [(Me 3 Si) 2 N] 2 V(o-Me 2 NCH 2 C 6 H 4 ) was synthesized from [(Me 3 Si) 2 N] 2 VCl(THF) and Li(o-Me 2 NCH 2 C 6 H 4 ) in 81% yield. Treatment of [(Me 3 Si) 2 N] 2 VCl(THF) with excess LiBH 4 in the presence of pyr afforded the vanadium tetrahydroborate [We recently reported the syntheses and structures of three-coordinate vanadium chalcogenolates of the form [(Me 3 Si) 2 N] 2 -VER [E = Se or Te; R = Si(SiMe 3 ) 3 or SiPh 3 ] 1 and demonstrated that in addition to being electrophilic by virtue of their electron-deficient, co-ordinatively unsaturated nature, they are susceptible to two-electron oxidation reactions. Based on these results, we thought it worthwhile to pursue the preparation of three-co-ordinate alkyl, aryl or hydride species {i.e. [(Me 3 -Si) 2 N] 2 VR}, particularly since little is known about organovanadium chemistry in non-cyclopentadienyl environments. 2 Unfortunately, isolation of species of this type was hindered by metallation of a bis(trimethylsilyl)amide ligand. 3-7 Nonetheless, facile loss of tetrahydrofuran (THF) from [(Me 3 Si) 2 N] 2 -VR(THF) (R = Me or Ph), while posing certain steric constraints on R, enabled these molecules to act as sources of '[(Me 3 Si) 2 N] 2 VR' fragments, much in the way (Mes) 3 V(THF) (Mes = 2,4,6-Me 3 C 6 H 2 ) 8,9 is an effective source of 'V(Mes) 3 '. 10-12 Thus, we have explored the reactivity of [(Me 3 Si) 2 N] 2 VR(THF) with a variety of reagents containing C᎐ ᎐ ᎐ N, C᎐ ᎐ ᎐ C and C᎐ ᎐ O bonds and the results are presented herein. Substitution of chloride in [(Me 3 Si) 2 N] 2 VCl(THF) for 2-thienyl, tetrahydroborate and o-dimethylaminomethylphenyl was also carried out and crystal structures of the latter two products are presented. Experimental GeneralStandard inert atmosphere glovebox a...

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Section: Resultsmentioning

confidence: 99%

Synthesis of N(SiMe3)2 supported vanadium(III) complexes, including hydrocarbyl, tetrahydroborate and azaalkenylidene derivatives †

Gerlach¹,

Arnold²

1997

J. Chem. Soc., Dalton Trans.

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“…No exchange is observed between 2-D 4 and C 6 H 6 under identical thermolytic conditions, although the conditions used to generate the metal benzyne complex is not surprising, since Teuben and co-workers have estimated relatively high barriers for formation of these species types. 5 Even though we were unable to obtain single crystals of complex 2, 13 C NMR spectroscopic data are consistent with an h 2 -benzyne ligand having inequivalent a-carbon resonances (157.6 and 156.6 ppm). Because of the skewing of the PNP phosphine arms, complex 2 displays also two broad resonances at 65.2 and 60.2 ppm in the 31 P NMR spectrum.…”

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confidence: 78%

“…3 In this work, we demonstrate through a series of deuteration and oxidation reactions that 1 can activate two arene ortho-C-H bonds in benzene, to ultimately furnish a rare example of a 3d transition metal benzyne complex. 4,5 Labeling studies in combination with theoretical analysis are provided in order to understand the mechanism of conversion of benzene to benzyne. Analogously, we also demonstrate that 1, by route of the unsaturated alkylidene species, A, can perform C-H activation of 2-picolines to yield the corresponding pyridyl complexes.…”

mentioning

confidence: 99%

“…Benzene is not the only substrate amenable to C-H activation since 2-picoline and 2-phenyl picoline react slowly (>4 days, N 2 excluded) at 25 C with 1 to afford the pyridyl complexes (PNP)V(CH 2 tBu)(h 2 -NC 5 RH 4 ) (R ¼ CH 3 (5) or Ph (6), respectively, Scheme 2). 6 Unfortunately, we were unable to isolate the product resulting from pyridine activation by precursor 1.…”

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confidence: 99%

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Intermolecular C–H bond activation of benzene and pyridines by a vanadium(iii) alkylidene including a stepwise conversion of benzene to a vanadium-benzyne complex

et al. 2010

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“…Similarly, the first isolated vanadium benzyne complex CpV(η 2 ‐ c ‐C 6 H 4 )(PMe 3 ) 2 was reported in 1995 (Cp = η 5 ‐C 5 H 5 ) by J. H. Teuben, by using phosphine groups on metal. It was obtained from the β‐hydrogen abstraction of benzene, at ambient temperature, from CpVPh 2 (PMe 3 ) 2 . In 1995, two other tantalum complexes of benzyne were isolated.…”

Section: Introductionmentioning

confidence: 99%

Short‐Lived Orthobenzyne Complexes with Early Transition Metals of Group IV. First Direct Characterization and Electronic Cartography by Coupling FVT/UV‐PES with Calculations

et al. 2018

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Short-lived η 2 -benzyne metallocene complexes [Cp 2 M(η 2 -c-C 6 H 4 )] with group IV metals are important intermediates in organic chemistry, their olefin insertion products being building blocks for aromatic and heterocyclic compounds. For the first time, an electronic cartography of these short-lived species has been obtained through the determination of their ionization potentials. They have been directly characterized in the gas phase by UV photoelectron spectroscopy, by monitoring, in situ, the thermal -H abstraction of benzene from [a]

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Structure and Reactivity of Mono(cyclopentadienyl)vanadium Alkynyl and Aryne Complexes

Cited by 42 publications

References 81 publications

Synthesis of N(SiMe3)2 supported vanadium(III) complexes, including hydrocarbyl, tetrahydroborate and azaalkenylidene derivatives †

Synthesis of N(SiMe3)2 supported vanadium(III) complexes, including hydrocarbyl, tetrahydroborate and azaalkenylidene derivatives †

Intermolecular C–H bond activation of benzene and pyridines by a vanadium(iii) alkylidene including a stepwise conversion of benzene to a vanadium-benzyne complex

Short‐Lived Orthobenzyne Complexes with Early Transition Metals of Group IV. First Direct Characterization and Electronic Cartography by Coupling FVT/UV‐PES with Calculations

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