New routes to molybdenum and tungsten carbyne complexes [M(CO) 2 (CPh)(η-C 5 H 4 R)](M = Mo or W, R = SnPh 3 ; M = W, R = H)

Treatment of the ethoxy carbenes [M(SnPh3)(CO)2{C(OEt)Ph}(η-C5H5)](M = Mo or W) with LDA or LDA/HMPA followed by PhC(O)Cl results in the carbyne complexes [M(CO)2(CPh)(η-C5H4SnPh3)]via anions [M(CO)2{C(OEt)Ph}(η-C5H4SnPh3)]–, while treatment of [W(SnPh3)(CO)3(η-C5H5)] with LiPh followed by TMEDA/MeC(O)Cl results in the carbyne [W(CO)2(CPh)(η-C5H5)].