Active role of a germylene ligand in promoting reactions of platinum complexes with oxygen and sulfur dioxide

The reaction of (Et3P)(2)PtGe[N(SiMe3)(2)](2) With dioxygen yields (Et3P)(2 )Pt(mu-eta(2)-O-2)Ge[N(SiMe3)(2)](2) (1). Exposure of 1 to light resulted i n a rearrangement to (Et3P)(2)PtO2Ge[N(SiMe3)(2)](2) (2a), the first exampl e of a bidentate, dianionic germanate ligand. The isomerization was judged to occur via an intramolecular O-O bond scission and rotation of the Pt-Ge bond. No free germylene was detected, and the reaction was found to be zero order. An analogue of 2a was prepared by direct reaction of (Ph3P)(2)PtO2 With Ge[N(SiMe3)(2)](2) yielding (Ph3P)(2)PtO2-Ge[N(SiMe3)(2)](2) (2b). Add ition of SO2 to 1 results in the formation of the bridging-sulfate (Et3P)(2 )Pt(mu-eta(2)-SO4)-Ge[N(SiMe3)(2)](2) (3). An infrared spectroscopy study o f the sulfate reaction was performed using oxygen-18. The results indicate that direct insertion of SO2 into the O-O bond does not occur; Formaldehyde was also observed to insert into the Pt-O bond of 1 giving (Et3P)(2)Pt(mu- eta(2)-OCH2OO)Ge[N(SiMe3)(2)](2) (5).