SOME REACTIONS OF THE PRODUCTS OF REACTIONS OF 1,4-BIS(TRIMETHYLSILYL)-1,3-BUTADIYNE WITH TITANOCENE AND ZIRCONOCENE

-3,5-bis(trimethylsilyl)titanacyclopenta-2,4-diene (1) and the seven-m embered zirconacyclocumulene 4,7-tris(trimethylsilyl)-3-(trimethylsily lethynyl) zirconacyclohepta-2,4,5,6-tetraene (2) react with sulfur mon ochloride to yield an identical product, thylsilylethynyl)-3,5-bis(tri methylsilyl)thiophene (3). A one-to-one mixture of the homo- and heter obimetallic bis-sigma,pi-acetylide bridged complexes (2)-C=CSiMe(3))M( mu-eta(1):eta(2)-C=CSiMe(3))Cp(2) (M = Zr (4), M = Ti (5)) is formed i n the reaction of zirconacyclocumulene 2 with three equivalents of Cp( 2)Ti(eta(2)-Me(3)SiC=CSiMe(3)). The reaction proceeds most likely via alkyne elimination, a C-C-single bond activation, and the cleavage of the starting diyne takes place.