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), andcis-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 NHEt 2, have given high yields of M(C⋮CC⋮CH)(CO) n Cp [M = W ( 1-W ), Mo ( 1-Mo ), n = 3; M = Fe, n = 2 ( 2 )]. Complex 1-W was metalated with LiNPr i 2; subsequent reactions with SiClMe 3 or PClPh 2 gave W(C⋮CC⋮CR)(CO) 3 Cp [R = SiMe 3 ( 3 ) or P(O)Ph 2 ( 4 )] in modest to high yield. Coupling of 1 with iodoarenes, catalyzed by a mixed Cu I −Pd 0 catalyst, gave M(C⋮CC⋮CAr) (CO) 3 Cp [M = W, Ar = Ph ( 5-W ), tol ( 6 ), C 6 H 4 OMe-4 ( 7 ), C 6 H 4 CO 2 Me-4 ( 8 ); M = Mo, Ar = Ph ( 5-Mo )]. Oxidative coupling of 1 (CuCl-tmed-O 2 ) gave {M(CO) 3 Cp} 2 (μ-C 8 ) [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 ]CH C(CN) 2 }(CO) 3 Cp ( 10 ). Substitution of CO by PPh 3 was difficult, but the Me 3 NO-induced reaction with 5-W afforded cis -W(C⋮CC⋮CPh)(CO) 2 (PPh 3 )Cp ( 11 ) in low yield. The X-ray crystal structures of 3 and 10, together with that of cis -W(C⋮CPh)(CO) 2 (PPh 3 )Cp ( 12 ), are reported.