SYNTHESIS, STRUCTURE, AND REACTIVITY OF A BIS(SILYLENE)CARBONYLRUTHENIUM COMPLEX AND A NOVEL ADDITION-REACTION OF PHOTOCHEMICALLY GENERATEDDIMETHYLSILYLENE TO BIS(SILYLENE) COMPLEXES CP(OC)M(SIME2...O(ME)...SIME2)(M= RU, FE)

Photolysis of CpRu(CO)(2)SiMe2SiMe3 (1a) with a low- or medium-pressur e Hg lamp for a long time caused the loss of a SiMe2 moiety to give Cp Ru(CO)(2)SiMe3 (2), perhaps through the photochemical dissociation of a CO ligand. This mechanism was supported by the quantitative formatio n of the bis(silylene)ruthenium complex Cp(OC)Ru(SiMe2... O(Me)... SiM e2) (3a) by photolysis of the (methoxydisilanyl)ruthenium complex CpRu (CO)(2)SiMe2SiMe2OMe (1b). The X-ray crystal structure analysis of 3a revealed that 3a has an almost planar Ru-Si-O-Si four-membered chelate ring with short Ru-Si bonds (2.316(3) and 2.311(3) Angstrom) and long Si .. O bonds (1.801(7) and 1.793(7) Angstrom). 3a reacts with MeOH i nstantaneously to give Cp(OC)Ru(H)(SiMe2OMe)(2) (4) quantitatively. Ph otolysis of CpM-(CO)(2)SiMe2SiMe2OMe (1b, M = Ru; 1c, M = Fe) or Cp(OC )M(SiMe2... O(Me)... SiMe2) (3a, M = Ru; 3b, M = Fe) with the photoche mical silylene precursor (SiMe2)(6) by means of a low-pressure Hg lamp afforded a mixture of 3a or 3b, disilanyl-silylene complexes Cp-(OC)M (=SiMe2<--O(Me)SiMe2SiMe2) (5a, M = Ru; 5b, M = Fe), and(SiMe2)(5). Tw o possible mechanisms for the addition of dimethylsilylene to 3 to giv e 5 were proposed.