The UV-Light Initiated Reaction of Organosilanes with Tungsten Hexacarbonyl: Formation of an Organosilylene Complex and Organosilylium Salts
Résumé
UV-irradiation of the diorganosilane [4-t-Bu-2,6-{P(O)(Oi-Pr)2}2C6H2]SiH2Ph in the presence of W(CO)6 provided a mixture consisting of the diorganosilylene tungsten pentacarbonyl complex [4-t-Bu-2,6-{P(O)(Oi-Pr)2}2C6H2](Ph)SiW(CO)5, 2, the organosiliconium salt [4-t-Bu-2,6-{P(O)(Oi-Pr)2}2C6H2Si(H)Ph]+[{(CO)5W}2H]–, 3, and an unidentified species. UV-irradiation of the triorganosilane [4-t-Bu-2,6-{P(O)(Oi-Pr)2}2C6H2]SiHPh2 in presence of W(CO)6 provided the organosiliconium salt [4-t-Bu-2,6-{P(O)(Oi-Pr)2}2C6H2SiPh2]+[{(CO)5W}2H]–, 6, whereas, under the same conditions, no reaction was observed between the tetraorganosilane [4-t-Bu-2,6-{P(O)(Oi-Pr)2}2C6H2]SiPh3 and W(CO)6. The reaction of compound 2 with Ph3C+PF6– gave the fluorine-substituted silylene complex [4-t-Bu-2,6-{P(O)(Oi-Pr)2}2C6H2](F)SiW(CO)5, 4, whereas the reactions of 3 with Ph4PBr and 5 with water gave the benzoxasilaphospholes 3a, 3b, and 7, respectively. The compounds 2 and 6 were isolated and characterized by 1H, 13C, 29Si, 31P NMR, and IR- spectroscopy, electrospray ionization mass spectrometry, and in case of 2 also by single-crystal X-ray diffraction analysis. The compounds 3, 3a, 3b, 4, and 7 were not isolated but identified unambiguously by NMR spectroscopy and electrospray ionization mass spectrometry.
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