Synthesis and Reactivity of Ru(II)/Chloro/Hydrido/Carbonyls with Cis Bulky Phosphines: An Unsaturated Ru(II) Monohydride

[RuCl2(CO)2(dtbpe)], dtbpe = tBu2PCH2CH2PtBu2 is synthesized as a mixture of two isomers and is converted to
[RuHCl(CO)2(dtbpe)], then [Ru(H)2(CO)2(dtbpe)]. The chloride trans to hydride in [RuHCl(CO)2(dtbpe)] can be
replaced by BF4- or PF6-, and reaction with NaB(3,5-(CF3)2C6H3)4 gives authentic, five-coordinate [RuH(CO)2(dtbpe)]+, characterized structurally by X-ray diffraction, which reveals the lack of agostic interactions. [Ru(H)2(CO)2(dtbpe)] reacts under mild conditions with CO to give [Ru(CO)3(dtbpe)], with ethylene to give C2H6 and
[Ru(C2H4)(CO)2(dtbpe)], and with D2 to give some [Ru(H)(D)(CO)2(dtbpe)]. These results are interpreted in terms
of relatively facile dissociation of one end of dtbpe from the metal.