A Cobalt Silacyclobutadiene Complex

The first silacyclobutadiene complex, (η5-cyclopentadienyl)[η4-1,2-bis(tert-butyldimethylsilyl)-3,4-di-tert-butyl-1-silacyclobutadiene]cobalt (1), was synthesized as red crystals by the reaction of the corresponding 4-silatriafulvene derivative with (cyclopentadienyl)dicarbonylcobalt at 80 °C in benzene. The X-ray analysis of 1 and theoretical calculations for a model silacyclobutadiene complex revealed that the electron accepting ability of the η4-silacyclobutadiene ligand is significantly smaller than that of a cyclobutadiene ligand in the analogous complex.