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

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Two new water-soluble ruthenium hydrides Cp′Ru(PTA) 2 H, Cp′ = C 9 H 7 – (Ind, 1 ) or C 8 H 9 – (Dp, 2 ), along with IndRu(PTA) 2 Cl ( 3 ) have been synthesized. DpRu(PTA) 2 H was synthesized by refluxing DpRu(PTA) 2 Cl with NaCO 2 H in methanol. IndRu(PTA) 2 H was unable to be generated in a similar manner due to complications in the synthesis of IndRu(PTA) 2 Cl. IndRu(PTA) 2 H was synthesized by conversion of the mixed-phosphine ruthenium complex IndRu(PTA)(PPh 3 )Cl into IndRu(PTA)(PPh 3 )H followed by ligand substitution of PPh 3 with 1,3,5-triaza-7-phosphaadamantane (PTA). Complexes 1 and 2 are stable and moderately soluble in water ( S 25°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) 2 Cl ( 3 ) ( S 25°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 D 2 O were monitored by 31 P NMR spectroscopy as a function of temperature: Δ H ‡ = 92 ± 3 kJ/mol, Δ S ‡ =–22 ± 2 J/mol·K. In addition, H/D exchange reactions of the 1,2-dihydropentalenyl (η 5 -C 8 H 9 –, Dp) analogue, 2, with D 2 O are also described along with the effects of pH on the 31 P NMR spectra.