Oxidation Reactions of [(Me₃Si)₂N]₂VX(THF) (X = Cl, Me, Ph) with CuCl, PhCH(O)CH₂, and Ph₂CN₂ and the Syntheses and Structures of the Vanadium(III) Anions {[(Me₃Si)₂N]₂VX₂}^- (X = Cl, Me)

Abstract

One-electron oxidation of [(Me3Si)2N]2VX(THF) (X = Cl, Me, Ph) with CuCl afforded the V(IV), d1 species [(Me3Si)2N]2VCl(X) in moderate yields after crystallization from acetonitrile. [(Me3Si)2N]2VCl2 has been characterized crystallographically. The methyl and phenyl derivatives were conveniently synthesized in one step from [(Me3Si)2N]2VCl(THF) by first reacting first with LiMe or MgPh2, prior to treatment with CuCl. Reaction of [(Me3Si)2N]2VCl(THF) with dilithioacetylide in the presence of tetramethylethylenediamine (TMEDA) proceeded with redistribution of the Cl ligands, as the anionic V(III) compound [Li(TMEDA)2]{[(Me3Si)2N]2VCl2} was obtained in 44% yield as purple crystals. The analogous dimethyl anion [Li(TMEDA)2]{[(Me3Si)2N]2VMe2} was synthesized in 66% yield as deep-blue, highly air-sensitive crystals on treatment of [(Me3Si)2N]2VCl(THF) with 2 equiv of LiMe in the presence of TMEDA. X-ray crystallography showed that both salts crystallized as well-separated cations and anions. The reaction between styrene oxide and [(Me3Si)2N]2VMe(THF) proceeded stepwise, first yielding the μ-O intermediate {[(Me3Si)2N]2VMe}2(μ-O) and then the V(V) terminal oxo [(Me3Si)2N]2V(O)(Me). Styrene oxide also oxidized [(Me3Si)2N]2VPh(THF) to [(Me3Si)2N]2V(O)(Ph), however, in this case the putative μ-O intermediate could not be isolated as a stable material. Diphenyldiazomethane was reduced by two electrons to an alkylidenehydrazido(2-) on displacing THF from [(Me3Si)2N]2VCl(THF) to form the V(V) complex [(Me3Si)2N]2V(Cl)(N2CPh2). A crystal structure showed the diazoalkane to be coordinated in a doubly-bent fashion.

A Transient VIII–Alkylidene Complex: Oxidation Chemistry Including the Activation of N2 to Afford a Highly Porous Honeycomb‐Like Framework

“…The solid state packing diagram for this complex displays a highly "porous" honeycomb-like framework along the activated N 2 unit. During the course of our investigation, we also discovered that the elusive V III alkylidene generated in these set of reactions can be trapped with a chelate p acid such as 2,2'-bipyridine (bpy).When the bis-alkyl precursor, readily prepared from a one-pot reaction of Li(PNP) and [VCl 3 (thf) 3 ] followed by alkylation with the appropriate stoichiometry of LiCH 2 tBu, [11] was treated with N 2 CPh 2 in diethyl ether, a gradual reaction ensued over a period of 12 h to afford the V V alkylidenediphenylmethylene hydrazido [12] complex [(PNP)V( = CHtBu)(N 2 CPh 2 )] (2) in 62 % yield after workup of the reaction mixture (Scheme 1). Likewise, treatment of 1 with O=PPh 3 in toluene over 24 h produces a color change from green to brown concurrent with formation of the alkylideneoxo complex [(PNP)V(=CHtBu)(O)] (3) and free PPh 3 (Scheme 1).…”

“…When the bis-alkyl precursor [(PNP)V(CH 2 tBu) 2 ] (1) (PNP = N[4-Me-2-(PiPr 2 )C 6 H 3 ] 2 À ), readily prepared from a one-pot reaction of Li(PNP) and [VCl 3 (thf) 3 ] followed by alkylation with the appropriate stoichiometry of LiCH 2 tBu, [11] was treated with N 2 CPh 2 in diethyl ether, a gradual reaction ensued over a period of 12 h to afford the V V alkylidenediphenylmethylene hydrazido [12] complex [(PNP)V( = CHtBu)(N 2 CPh 2 )] (2) in 62 % yield after workup of the reaction mixture (Scheme 1). Likewise, treatment of 1 with O=PPh 3 in toluene over 24 h produces a color change from green to brown concurrent with formation of the alkylideneoxo complex [(PNP)V(=CHtBu)(O)] (3) and free PPh 3 (Scheme 1).…”

Highlights in the Renaissance of Amidometal Chemistry

“…[185] The reactivity of this compound has been systematically and thoroughly investigated. [185,186] The reaction of 50 with KH is interesting because supramolecular organization occurs through agostic CÀH´´ṕ otassium interactions with the formation of a V 2 K 2 ensemble (Scheme 40). [187] Scheme 40.…”

Cover Picture: 2,4,5‐Trinitroimidazole‐Based Energetic Salts (Chem. Eur. J. 14/2007)

“…When the bis‐alkyl precursor [(PNP)V(CH 2 t Bu) 2 ] ( 1 ) (PNP=N[4‐Me‐2‐(P i Pr 2 )C 6 H 3 ] 2 − ), readily prepared from a one‐pot reaction of Li(PNP) and [VCl 3 (thf) 3 ] followed by alkylation with the appropriate stoichiometry of LiCH 2 t Bu,11 was treated with N 2 CPh 2 in diethyl ether, a gradual reaction ensued over a period of 12 h to afford the V V alkylidene–diphenylmethylene hydrazido12 complex [(PNP)V(CH t Bu)(N 2 CPh 2 )] ( 2 ) in 62 % yield after workup of the reaction mixture (Scheme ). Likewise, treatment of 1 with OPPh 3 in toluene over 24 h produces a color change from green to brown concurrent with formation of the alkylidene–oxo complex [(PNP)V(CH t Bu)(O)] ( 3 ) and free PPh 3 (Scheme ) 11.…”