METAL CARBENE, METAL VINYLIDENE, AND METAL ALKYNE COMPLEXES - REACTION OF ACETYLIDES WITH (ETA(5)-C5H5)M(CO)(2)(NO) (M=CR, MO, W)

Reaction of (eta(5)-(CH5)-H-5)M(CO)(2)(NO) (M = MO Or W) (1) with LiC= CR (2) and subsequent addition of an electrophile leads either to a vi nylidene or an eta(2)-alkyne metal complex. [(eta(5)-C5H5)(CO)(NO)]M=C =C(R)(R') derivatives are formed when alkyl or aryl acetylides (R = al kyl or C6H5) and either C-electrophile or dilute acid (R' = CH3 or H) are used. [(eta(5)-C5H5)(CO)(NO)]M(R-C=C-R') (R = (CH3)(3)Si, CH3, all yl, or C6H5; R' = (CH3)(3)Si) is formed either when LiC=C-Si(CH3)(3) i s used and the addition product is trapped by allylbromide, trifluorom ethane sulfonate, or (trimethylsilyl)chloride, or when the addition pr o duct of LiC=C-C6H5 with 1 is trapped by (trimethylsilyl)chloride. Th e structure of [(eta-C5H5)(CO)-(NO)]W[H3C-C=C-Si(CH3)(3)] was determin ed by X-ray diffraction. Under the conditions used here, independent o f the identity of the acetylide or electrophile, (eta(5)-C5H5)Cr(CO)(2 )-(NO) leads only to the carbene complexes [(eta(5)-C5H5)(CO)(NO)]Cr=C (OCH3)(C=C-R) (R = C6H5 or (CH3)(3)Si) Addition of secondary amines to carbene complex [(eta(5)-C5H5)(CO)(NO)]-Cr=C(OCH3)(C=C-C6H5) is discu ssed. Synthesis of [(eta(5)-C5H5)(CO)(NO)]W=C=CH2 is described.