The UV‐Light Initiated Reaction of Organosilanes with Tungsten Hexacarbonyl: Formation of an Organosilylene Complex and Organosilylium Salts

UV‐irradiation of the diorganosilane [4‐ t Bu‐2,6‐{P(O)(O i Pr) 2 } 2 C 6 H 2 ]SiH 2 Ph in the presence of W(CO) 6 provided a mixture consisting of the diorganosilylene tungsten pentacarbonyl complex [4‐ t Bu‐2,6‐{P(O)(O i Pr) 2 } 2 C 6 H 2 ](Ph)SiW(CO) 5 ( 2 ), the organosilylium salt [4‐ t Bu‐2,6‐{P(O)(O i Pr) 2 } 2 C 6 H 2 Si(H)Ph] + [{(CO) 5 W} 2 H] – ( 3 ), and an unidentified species. UV‐irradiation of the triorganosilane [4‐ t Bu‐2,6‐{P(O)(O i Pr) 2 } 2 C 6 H 2 ]SiHPh 2 in presence of W(CO) 6 provided the organosilylium salt [4‐ t Bu‐2,6‐{P(O)(O i Pr) 2 } 2 C 6 H 2 SiPh 2 ] + [{(CO) 5 W} 2 H] – ( 6 ) whereas, under the same conditions, no reaction was observed between the tetraorganosilane [4‐ t Bu‐2,6‐{P(O)(O i Pr) 2 } 2 C 6 H 2 ]SiPh 3 and W(CO) 6 . The reaction of compound 2 with Ph 3 C + PF 6 – gave the fluorine‐substituted silylene complex [4‐ t Bu‐2,6‐{P(O)(O i Pr) 2 } 2 C 6 H 2 ](F)SiW(CO) 5 ( 4 ) whereas the reactions of 3 with Ph 4 PBr and 5 with water gave the benzoxasilaphospholes 3a , 3b , and 7 , respectively. The compounds 2 and 6 were isolated and characterized by 1 H, 13 C, 29 Si, 31 P 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.