Group 4 Metallocene Complexes of Tris(trimethylsilyl)silylacetylene and Related Alkynes

Oligosilyl-substituted alkyne complexes of group 4 metallocenes have been prepared by reaction of group 4 metallocene dichlorides with magnesium in the presence of the respective alkyne. Depending on the alkyne substitution pattern, either metallacyclopentadienes or metallocene alkyne complexes were formed. In order to suppress the oxidative coupling process, PMe3 was added to obtain the metallocene alkyne complex base adducts. The reaction of 1,4-bis[tris(trimethylsilyl)silyl]butadiyne with zirconocene caused the formation of a 1,4-bis[tris(trimethylsilyl)silyl]-substituted zirconacyclocumulene. Reactions of zirconacyclopentadienes with iodine proceeded to the expected 1,4-diiodobuta-1,3-dienes.