Active Role of a Germylene Ligand in Promoting Reactions of Platinum Complexes with Oxygen and Sulfur Dioxide

The reaction of (Et3P)2PtGe[N(SiMe3)2]2 with dioxygen yields (Et3P)2Pt(μ-η2-O2)Ge[N(SiMe3)2]2 (1). Exposure
of 1 to light resulted in a rearrangement to (Et3P)2PtO2Ge[N(SiMe3)2]2 (2a), the first example 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)2PtO2 with Ge[N(SiMe3)2]2 yielding (Ph3P)2PtO2Ge[N(SiMe3)2]2 (2b). Addition of SO2 to 1 results in the formation of the bridging sulfate (Et3P)2Pt(μ-η2-SO4)Ge[N(SiMe3)2]2 (3). An infrared spectroscopy study of 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)2Pt(μ-η2-OCH2OO)Ge[N(SiMe3)2]2 (5).