ALKYL, ARYL, VINYL, ALKYNYL AND CARBENE DERIVATIVES OF CYCLOHEPTATRIENYLMOLYBDENUM COMPLEXES

A series of cycloheptatrienylmolybdenum complexes of general formulation [MoR(CO)(PR'3)(eta-C7H7)] (R = Me, Ph, vinyl or alkynyl; R' = Me or Ph) have been synthesised via reaction of [MoBr(CO)(PR'3)-(eta-C7H7)] (R' = Me 1 or Ph 2) with appropriate organolithium or Grignard reagents. Specific complexes reported are [MoMe(CO)(PR'3)(eta-C7H7)] (R' = Me or Ph), [MoPh(CO)(PMe3)(eta-C7H7)], [Mo(C6F5)(CO)(PPh3)(eta-C7H7)], [Mo(CH=CH2) (CO) (PR'3)(eta - C7H7)](R' = Me or Ph) and [Mo(C=CR'')(CO)(PR'3)(eta-C7H7)] (R' = Me, R'' = Ph or Bu(t); R' = R'' = Ph). A new synthesis of [MoMe(Ph2PCH2CH2PPh2)(eta-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)(eta-C7H7)]+ has been generated chemically and isolated. Protonation by HBF4.Et2O of the vinyl complex [Mo(CH=CH2)(CO)(PMe3) (eta-C7H7)] followed by treatment with PR''3 affords the 'trapped' carbene adducts [Mo{CH(PR''3)Me}(CO)(PMe3)(eta-C7H7)][BF4] (R''=OMe or Ph). The first examples of stable cycloheptatrienylmolybdenum carbene complexes [Mo(CCH2CH2CH2O)-(CO)(PR'3)(eta-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.