Intramolecular Hydrogen Site Exchange in an HRu(SiHPh2) Moiety

RuH(Ph)(CO)L2 (L = PtBu2Me) reacts with SiH2Ph2 to give first benzene and RuH(SiHPh2)(CO)L2, and then RuH3(SiHPh2)(CO)L2 and Ru(H)2(CO)L2, the trihydride being formed by a dehydrogenative silane coupling reaction when excess SiH2Ph2 is present. Variable-temperature spin saturation transfer experiments reveal exchange between Ha and Hb in RuHa(SiHbPh2)(CO)L2; this occurs both by an intramolecular mechanism and (when SiH2Ph2 is present) by a mechanism dependent on SiH2Ph2 concentration. Spin saturation transfer also reveals exchange between all three of the above complexes via addition/loss of SiH2Ph2 or H2.