Coupling of transition metal carbynes with a methylene arsane moiety: Structure of Tp '(CO)(2)W C-As=C(NMe2)(2) [Tp ' = HB(3,5-Me2HC3N2)(3)]

Condensation of Tp'(CO)(2)M=CCl [1a, M = Mo; 1b, W; Tp' = HB(3,5-Me2HC3N2)(3)] with the arsaalkene Me3SiAs=C(NMe2)(2) afforded the novel arsaalkenyl carbyne complexes Tp'-(CO)(2)M=C-As=C(NMe2)(2) (2a) (M = Mo) and 2b (M = W). Methylation of 2a and 2b, occurred at the arsenic atom to give the complexes [Tp'(CO)(2)M=CAs(Me)C(NMe2)(2)](SO3CF3) 3a (M = Mo) and 3b (M = W). Compounds 2a,b and 3a,b have been characterized by IR and H-1 and C-13 NMR spectroscopy. In addition, the molecular structure of 2b has been determined by a single-crystal X-ray structural analysis.