Reactivity of Silanes with (tBuPONOP)Ruthenium Dichloride: Facile Synthesis of Chloro-Silyl Ruthenium Compounds and Formic Acid Decomposition

The coordination of tBuPONOP (tBuPONOP = 2,6-bis(ditertbutylphosphinito)pyridine) to different ruthenium starting materials, to generate (tBuPONOP)RuCl2, was investigated. The 16-electron species (tBuPONOP)Ru(H)Cl was produced from the reaction of triethylsilane with (tBuPONOP)RuCl2. Reactions of (tBuPONOP)RuCl2 with both phenylsilane or diphenylsilane afforded the 16-electron hydrido-silyl species (tBuPONOP)Ru(H)(PhSiCl2) and (tBuPONOP)Ru(H)(Ph2SiCl), respectively. Reactions of all three of these complexes with silver triflate afforded the simple salt metathesis products of (tBuPONOP)Ru(H)(OTf), (tBuPONOP)Ru(H)(PhSiCl(OTf)), and (tBuPONOP)Ru(H)(Ph2Si(OTf)). Formic acid dehydrogenation was performed in the presence of triethylamine (TEA) using these (tBuPONOP)Ru complexes as catalysts, and each species proved competent for gas pressure generation of CO2 and H2.