Water-Soluble Triisopropylphosphine Complexes of Ruthenium(II): Synthesis, Equilibria, and Acetonitrile Hydration

The complex [RuCl(NCMe) 4 (P i Pr 3 )]BF 4 ( 1 ) and its water-soluble dicationic products of chloride replacement by P i Pr 3 ( 2 ), P(OMe) 3 ( 3 ), Hpz ( 4 ), MeOH ( 5 ), and H 2 O ( 6 ) have been prepared and characterized. The chloride dissociation constant of 1 in water ( K d = 2.0 M) and the p K a (10.5) for the deprotonation of the water ligand of 6 have been determined by NMR methods. The conjugate base of 6, [Ru(OH)(NCMe) 4 (P i Pr 3 )] + ( 7 ), has been observed to isomerize into an amidate complex in route to acetonitrile hydration. Consistently, 6 has been found to catalyze the selective hydration of acetonitrile to acetamide in aqueous solution at pH 10.5 and 353 K, with initial TOF about 50 h −1 .