FORMATION OF DERIVATIVE CARBYNE COMPLEXES FROM TP'(CO)(2)M-CCH3 (M = MO, W)

Chloride displacement from Tp'(CO)(2)M=CCl (M = Mo, W (1); Tp' = hydri dotris(3,5-dimethylpyrazolyl)borate) with LiMe2Cu affords the methylca rbyne complex Tp'(CO)(2)M=CCH3 (M = Mo (2), W (3)). Deprotonation of t his methylcarbyne forms [Tp'(CO)(2)M=C=CH2](-)(M = Mo, W (4)), a nucle ophilic vinylidene anion which reacts with a variety of substrates. Re action of 4 with CH3I yields Tp'(CO)(2)W=CCH2CH3 (5), while PhC(O)H yi elds Tp'(CO)(2)W=CCH2CH(OH)(Ph) (8) and PhC(O)CH3 yields Tp'(CO)(2)W=C CH2C(OH)(CH3)(Ph) (10). In the presence of base complex 8 undergoes el imination to form a conjugated vinyl carbyne complex Tp'(CO)(2)W=CCH=C H(Ph) (11). Reaction of 4 with PhC(O)Cl and then base forms Tp'(CO)(2) W=CCH2C(O)Ph (14), which rearranges in solution to a metallafuran comp lex, Tp'(CO)(2)WCHCHC(O)Ph (15). Spectroscopic data suggests that a di nuclear intermediate, Tp'(CO)(2)W=CCH2CPh(OH)CH2C=W(CO)(2)Tp' (13), is first formed from 4 and PhC(O)Cl before the addition of base produces the expected monomeric product, Tp'(CO)(2)W=CCH2C(O)Ph (14).