SPECTROSCOPIC INVESTIGATION OF THE REACTIVITY OF CP-ASTERISK-RU(PIPR2PH)X TOWARD H-2 AND SILANES - FORMATION IN SOLUTION OF CP-ASTERISK-RU(PIPR2PH)(H)3 AND CP-ASTERISK-RU(PIPR2PH)(H)2Y (Y = HALIDE, OR, AND SIR'3)

Reaction of CpRuLX (L = PiPr2Ph; X = Br, I, OSiPh3, NHPh, and OCH2CF3 , called OR(f)) with H2 gives, at -60-degrees-C, CpRuLX(H)2, where th e two hydride ligands are assigned cisoid positions using H-1 NMR spec tra. These molecules (except X = Br and 1) react with additional H2 to give CpRuL(H)3 and liberate HX. Mechanistic possibilities are discus sed. Reaction of CpRuL(OR(f)) with HSiR3 (R = Me, Ph, OMe) gives Cp*R uL(H)2SiR3 and (RfO)SiR3. Reaction of CpRuL(OR(f)) with H2SiPh2 gives the two products CpRuL(H)2(SiXPh2) (X = H and OR(f)). Reversible equ ilibria make these species unstable toward isolation. Mechanistic stud ies are consistent with the presence of a common intermediate, for whi ch H2SiPh2 and HSi(ORf)Ph2 compete.