Reactivity of RuCl2(CO)(PtBu2Me)2toward H2and Brønsted Acids: Aggregation Triggered by Protonation and Phosphine Loss

Abstract
Reaction of H2 with RuCl2(CO)L2 (L = PtBu2Me) in benzene forms RuHCl(CO)L2 and HCl. The latter reacts with RuCl2(CO)L2 to give [LH][Ru2Cl5(CO)2L2] and [LH]Cl. The Ru2Cl5(CO)2L2- ion is detected (NMR) as several isomers, and is shown by X-ray diffraction to have a face-shared bioctahedral structure: LCl(OC)Ru(μ-Cl)3Ru(CO)ClL-. The loss of phosphine from Ru(II) is triggered by electrophilic attack, but not directly on P or on the Ru−P bond. It is shown (low-temperature NMR studies) that HCl reacts with RuHCl(CO)L2 to give initially RuCl2(H2)(CO)L2, in which H2 is trans to Cl. From this study, and also direct observation of the reaction of HCl with RuCl2(CO)L2 to produce Ru2Cl5(CO)2L2-, the Brønsted basicity of chloride in RuCl2(CO)L2 is established. This accounts for its reaction with PhC2H and NEt3 to give Ru(C2Ph)Cl(CO)L2. Crystallographic data (−173 °C) for [PtBu2MeH][Ru2Cl5(CO)2(PtBu2Me)2]: a = 16.418(2)Å, b = 12.578(2)Å, c = 20.044(3)Å, β = 103.38(1)° with Z = 4 in space group P21/a.

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