Syntheses and Chemistry of the Diynyl Complexes M(C⋮CC⋮CH)(CO)3(η-C5H5) (M = Mo, W): Crystal Structures of W(C⋮CC⋮CSiMe3)(CO)3(η-C5H5), W{C⋮CC[CH=C(CN)2]=C(CN)2}(CO)3(η-C5H5), and cis-W(C⋮CPh)(CO)2(PPh3)(η-C5H5)

Reactions of buta-1,3-diyne with appropriate metal halides, carried out in the presence of CuI in NHEt2, have given high yields of M(C⋮CC⋮CH)(CO)nCp [M = W (1-W), Mo (1-Mo), n = 3; M = Fe, n = 2 (2)]. Complex 1-W was metalated with LiNPri2; subsequent reactions with SiClMe3 or PClPh2 gave W(C⋮CC⋮CR)(CO)3Cp [R = SiMe3 (3) or P(O)Ph2 (4)] in modest to high yield. Coupling of 1 with iodoarenes, catalyzed by a mixed CuI−Pd0 catalyst, gave M(C⋮CC⋮CAr) (CO)3Cp [M = W, Ar = Ph (5-W), tol (6), C6H4OMe-4 (7), C6H4CO2Me-4 (8); M = Mo, Ar = Ph (5-Mo)]. Oxidative coupling of 1 (CuCl-tmed-O2) gave {M(CO)3Cp}2(μ-C8) [M = W (9-W), Mo (9-Mo)]. Addition of tetracyanoethene to 1-W occurred at the C⋮C triple bond further from the metal atom, to give W{C⋮CC[=C(CN)2]CHC(CN)2}(CO)3Cp (10). Substitution of CO by PPh3 was difficult, but the Me3NO-induced reaction with 5-W afforded cis-W(C⋮CC⋮CPh)(CO)2(PPh3)Cp (11) in low yield. The X-ray crystal structures of 3 and 10, together with that of cis-W(C⋮CPh)(CO)2(PPh3)Cp (12), are re...