Alkyl, aryl, vinyl, alkynyl and carbene derivatives of cycloheptatrienylmolybdenum complexes
Abstract
A series of Cycloheptatrienylmolybdenum complexes of general formulation [MoR(CO)(PR′3)(η-C7H7)](R = Me, Ph, vinyl or alkynyl; R′= Me or Ph) have been synthesised via reaction of [MoBr(CO)(PR′3)-(η-C7H7)](R′= Me 1 or Ph 2) with appropriate organolithium or Grignard reagents. Specific complexes reported are [MoMe(CO)(PR′3)(η-C7H7)](R′= Me or Ph), [MoPh(CO)(PMe3)(η-C7H7)], [Mo(C6F5)(CO)(PPh3)(η-C7H7)], [Mo(CHCH2)(CO)(PR′3)(η-C7H7)](R′= Me or Ph) and [Mo(CCR″)(CO)(PR′3)(η-C7H7)](R′= Me, R″= Ph or But; R′= R″= Ph). A new synthesis of [MoMe(Ph2PCH2CH2PPh2)(η-C7H7)] is also reported. Cyclic voltammetric studies reveal that some of the complexes undergo reversible, one-electron oxidation processes, and the radical cation [MoMe(Ph2PCH2CH2PPh2)(η-C7H7)]+ has been generated chemically and isolated. Protonation by HBF4·Et2O of the vinyl complex [Mo(CHCH2)(CO)(PMe3)(η-C7H7)] followed by treatment with PR″3 affords the ‘trapped’ carbene adducts [Mo{CH(PR″3) Me}(CO)(PMe3)(η-C7H7)][BF4](R″= OMe or Ph). The first examples of stable Cycloheptatrienylmolybdenum carbene complexes [Mo([graphic omitted])-(CO)(PR′3)(η-C7H7)][PF6](R′= Me or Ph), have been obtained via respective reaction of 1 and 2 with a but-3-yn-1-ol-[NH4][PF6] mixture in methanol.