Synthesis and reactivity of Ru(II)/chloro/hydrido/carbonyls with cis bulkyphosphines: An unsaturated Ru(II) monohydride

[RuCl2(CO)(2)(d'bpe)], d'bpe = (Bu2PCH2CH2PBu2)-Bu-t-Bu-t is synthesized as a mixture of two isomers and is converted to [RuHCl(CO)(2)(d'bpe)], then [ Ru(H)(2)(CO)(2)(d'bpe)]. The chloride trans to hydride in [RuHCl(CO)(2)(d'b pe)] can be replaced by BF4- or PF6-, and reaction with NaB(3,5-(CF3)(2)C6H 3)(4) gives authentic, five-coordinate [RuH(CO)(2)(d'bpe)](+), characterize d structurally by X-ray diffraction, which reveals the lack of agostic inte ractions. [Ru(H)(2)(CO)(2)(d'bpe)] reacts under mild conditions with CO to give [Ru(CO)(3)(d'bpe)], with ethylene to give C2H6 and [Ru(C2H4)(CO)(2)(d' bpe)], and with D-2 to give some [Ru(H)(D)(CO)(2)(d'bpe)]. These results ar e interpreted in terms of relatively facile dissociation of one end of d'bp e from the metal.