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