Activation of the SiH bond of silanes in photochemical reactions with W(CO)6: Hydrosilylation of ketones and dehydrosilylation of alcohol by H2SiPh2

Photolysis of W(CO)6 in the presence of H2SiPh2, H2SiEt2, and HSiEt3 in n-heptane leads to SiH bond activation and to the formation of a WH bond. In photochemical reaction of W(CO)6 with HSiEt3 in cyclohexane-d12, η2-coordination of the SiH bond to the tungsten atom and the existence of a two-electron, three-centre SiH⋯W bond is supported by 1H NMR spectroscopy due to the detection of high-field resonance at δH −8.58 (heptet, 3JHH = 1.6 Hz, 1JWH = 35 Hz, 1JSiH = 89 Hz). The photochemically activated W(CO)6 was tested as a catalyst in the hydrosilylation of ketones, RR′CO (R = Me, R′ = Me, iPr, nPr, Ph), by diphenylsilane. The same activation of the SiH bond of H2SiPh2 by tungsten(0) was applied in dehydrogenative silylation of 2-propanol and in transformation of H2SiPh2 to disiloxane Ph2HSiOSiHPh2 in the presence of water. The products of these reactions (organosilicon compounds) were characterized by GC–MS and NMR spectroscopy.

Graphical abstractPhotolysis of W(CO)6 in the presence of hydrosilanes in n-heptane solution leads to SiH bond activation and to the formation of a WH bond. The photochemical activation of W(CO)6 has been found effective for both the hydrosilylation of ketones as well as the dehydrosilylation of 2-propanol and water by H2SiPh2.Figure optionsDownload full-size imageDownload as PowerPoint slide