LAUSR

Reactions of silanone(silyl)tungsten and -molybdenum complexes Cp*(OC)2M{O═SiMes2(DMAP)}(SiMe3) (M = W (1a), Mo (1b), Cp* = η5-C5Me5, Mes = 2,4,6-Me3C6H2, DMAP = 4-(Me2N)C5H4N) with MesCNO, (Me2SiO)3, MeOH, and H2O were investigated. No silanone trapping product was detected in the reaction of 1 with MesCNO and (Me2SiO)3, while reactions of 1 with MeOH afforded the addition product Mes2Si(OMe)OH (5). The hydrolysis of molybdenum complex 1b afforded silanediol Mes2Si(OH)2 (8) as a main product with a trace amount of Mes2Si(OH)OSiMe3 (9), while that of the tungsten analogue 1a gave siloxysilanol 9 as the sole product, indicating that product distribution in the hydrolysis strikingly depends on the metal fragments. A theoretical investigation revealed that the product distribution difference between tungsten and molybdenum complexes arises from the difference in electrophilicity of the silicon atom in the silanone ligand and that of the lability for oxidative addition of water to the MII–L fragment.