Preparation and Structure of New Phenylplatinum Complexes Containing Silsesquioxane as a Monodentate or Bidentate Ligand

Incompletely condensed silsesquioxanes, R7Si7O9(OH)3 (R = cyclo-C5H9, iso-C4H9), react with trans-[PtI(Ph)(L)2] (L = PEt3, PMe2Ph) at room temperature in the presence of Ag2O to yield platinum complexes with a monodentate O-coordinated silsesquioxane, trans-[Pt{O10Si7R7(OH)2}(Ph)(L)2] (1a: R = cyclo-C5H9; L = PEt3, 1b: R = iso-C4H9; L = PEt3, 2a: R = cyclo-C5H9; L = PMe2Ph, 2b: R = iso-C4H9; L = PMe2Ph). Reactions of silsesquioxanes with trans-[PtI(Ph)(PPh3)2] in the presence of Ag2O at 55 °C afford unexpected Pt−Ag heterobimetallic complexes, [Pt{O11Si7R7(OH)(AgPPh3)}(Ph)(PPh3)] (3a: R = cyclo-C5H9, 3b: R = iso-C4H9), and a hydroxo-bridged dinuclear platinum complex, anti-[{PtPh(PPh3)}2(μ-OH)2] (4). These complexes were isolated and characterized by X-ray crystallography and 1H, 31P, 29Si, and 13C NMR spectroscopy. The crystal structures of 3a and 3b show a square-planar coordination around the Pt center bonded to Ph, PPh3, and bidentate O,O-coordinated silsesquioxane. One of the coordinated oxygen atoms is also bound to the AgPPh3 group.