Reactions of a Spiro Trisilane with Palladium Complexes: Synthesis and Structure of Tris(organosilyl)CpPdIV and Bis(organosilyl)(μ-organosilylene)PdII2 Complexes

1,1,6,6-Tetramethyl-1,5,6-trisilaspiro[4.4]nonane was reacted with bis( tert -alkyl isocyanide)palladium(0) and (η 5 -cyclopentadienyl)(η 3 -allyl)palladium(II) through oxidative addition of the Si−Si bonds to afford a dinuclear palladium(II) complex and a stable palladium(IV) complex, respectively. The latter palladium(IV)-complex-catalyzed ring-opening polymerization of 1,1,2,2-tetramethyl-1,2-disilacyclopentane gives organosilicon polymers with high molecular weight.