Electron-rich siloxane–platinum complexes — Synthesis, structures, and reactivity

Abstract

New platinasiloxanes were synthesized and their reactivity was studied. Oxidative addition of (HSiMe2)2O to Pt(PEt3)3 led to dehydrogenation and quantitative formation of the four-membered platinacyclosiloxane [(PEt3)2Pt((SiMe2)2O)] which was characterized by X-ray diffraction. This complex was stable towards non-polar substrates and aerobic conditions, but reacted readily with electrophiles and Lewis acids. Reaction with MeI resulted in ring opening, while MeOTf gave an oxonium complex, with retention of the platinacycle structure. A complex resulting from BF3 coordination to the ring oxygen atom was also obtained. An unprecedented open-chain diplatinasiloxane containing the Pt–Si–O–Si–O–Si–Pt fragment was formed by oxidative addition of H–SiMe2–O–SiMe2–O–SiMe2–H to Pt(PEt3)3 and it was characterized by X-ray diffraction.Key words: cyclosiloxane, metallacycle, platinum silyl, Lewis base, oxidative addition.