Formation and Ring Expansion of Germaplatinacycles via Dehydrogenative Ge−Ge and Ge−Pt Bond-Forming Reactions

The bis(germyl)platinum complex [Pt(GeHPh2)2(dmpe)] (1) (dmpe = 1,2-bis(dimethylphosphino)ethane) reacts with a small excess of H2GePh2 at 90 °C to produce four-membered germaplatinacycle [Pt(GePh2GePh2GePh2)(dmpe)] (2). Further reaction of 2 with excess H2GePh2 at 90 °C forms tetragermaplatinacyclopentane [Pt(GePh2GePh2GePh2GePh2)(dmpe)] (3), while 3 is obtained also by the direct reaction of excess H2GePh2 with 1 for a prolonged period. Complexes 1−3 were characterized by X-ray crystallography and NMR spectroscopy. Germaplatinacycles 2 and 3 react with H3GePh to cause cleavage of the Pt−Ge bonds and formation of the oligogermanes H(GePh2)3H and H(GePh2)4H, respectively.