The reactions of OsH(Ph)(CO)L-2 (L = P'Bu2Me) with HSiMe3, H2SiPh3 or H3SiPh produce benzene and OsH3(silyl)(CO)L-2, which is characterized as a fac-H3OsP3 shape capped on the H-3 face by the silyl group. For H2SiPh2 and H3SiPh, these reactions are shown proceed through an intermediate Os(H)(2)(silylene)(CO)L-2 species. OsHF(CO)L-2 reacts with these silanes to give the same OsH3 product (and silyl-F). These reactions can be combined to effect osmium catalysis of conversion of Si-H + H2C=CHF to fluorosilane and H2C=CH2 from OsH3(SiMe3)(CO)L-2, or from the catalyst precursor OsHF(CO)L-2. (C) 2004 Elsevier B.V. All rights reserved.