Arene-Ruthenium(II) Complexes Containing Inexpensive Tris(dimethylamino)phosphine: Highly Efficient Catalysts for the Selective Hydration of Nitriles into Amides

The catalytic hydration of nitriles into amides, in water under neutral conditions, has been studied using a series of arene-ruthenium(II) derivatives containing the commercially available and inexpensive ligand tris(dimethylamino)phosphine. Among them, best results were obtained with the complex [RuCl2(eta(6)-C6Me6){P(NMe2)(3)}], which selectively provided the desired amides in excellent yields and short times (TOF values up to 11 400 h(-1)). The process was operative with both aromatic, heteroaromatic, aliphatic, and alpha,beta-unsaturated organonitriles and showed a high functional group tolerance. The stability of [RuCl2(eta(6)-C6Me6){P(NMe2)(3)}] in water was evaluated, observing its progressive decomposition into the less-active dimethylamine nithenium(II) complex [RuCl2(eta(6)-C6Me6)(NHMe2)] by hydrolysis of the coordinated P(NMe2)(3) ligand. The X-ray crystal structure determination of the toluene complex [RuCl2(eta(6)-C6H5Me){P(NMe2)(3)}] is also included.