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 Bu^t; 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.