The Synthesis, Structure, and H/D Exchange Reactions of Water-Soluble Half-Sandwich Ruthenium(II) Hydrides of Indenyl and Dihydropentalenyl

Two new water-soluble ruthenium hydrides Cp′Ru­(PTA)2H, Cp′ = C9H7– (Ind, 1) or C8H9– (Dp, 2), along with IndRu­(PTA)2Cl (3) have been synthesized. DpRu­(PTA)2H was synthesized by refluxing DpRu­(PTA)2Cl with NaCO2H in methanol. IndRu­(PTA)2H was unable to be generated in a similar manner due to complications in the synthesis of IndRu­(PTA)2Cl. IndRu­(PTA)2H was synthesized by conversion of the mixed-phosphine ruthenium complex IndRu­(PTA)­(PPh3)Cl into IndRu­(PTA)­(PPh3)H followed by ligand substitution of PPh3 with 1,3,5-triaza-7-phosphaadamantane (PTA). Complexes 1 and 2 are stable and moderately soluble in water (S25°C = 16 mg/mL for 1 and ∼20 mg/mL for 2). The Ru hydrides react with chlorinated solvents, in the case of 1 yielding the challenging synthesize IndRu­(PTA)2Cl (3) (S25°C = 17 mg/mL). The synthesis, isolation, and reactivity of 1–3 are described including crystal structures of 1, 2, 3, and [IndRu­(PTA)3]­(Cl). H/D exchange reactions of 1 with D2O were monitored by 31P NMR spectroscopy as a function of temperature: ΔH‡ = 92 ± 3 kJ/mol, ΔS‡ =–22 ± 2 J/mol·K. In addition, H/D exchange reactions of the 1,2-dihydropentalenyl (η5-C8H9–, Dp) analogue, 2, with D2O are also described along with the effects of pH on the 31P NMR spectra