Bis(allyl)ruthenium(rV) complexes containing water-soluble phosphane ligands: Synthesis, structure, and application as catalysts in the Selective hydration of organonitriles into amides

Article abstract of DOI:10.1002/chem.201001152

The novel mononuclear ruthenium(IV) complexes [RuCl₂(η ³: η³-C₁₀H₁₆)(L)] [L = (meta-sulfonatophenyl)diphenylphosphane sodium salt (TPPMS) (2a), 1,3,5-triaza-7-phosphatricyclo[3.3.1.1^3,7]decane (PTA) (2b), 1-benzyl-3,5-diaza-1-azonia-7-phosphatricyclo[3.3.1.1^3,7]decane chloride (PTABn) (2c), 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane (DAPTA) (2d), and 2,4,10-trimethyl-1,2,4,5,7,10-hexaaza-3-phosphatricyclo[3.3.1. 1^3,7]decane (THPA) (2e)] have been synthesized by treatment of the dimeric precursor [{RuCl(μ-Cl)((η³: η³-C ₁₀H₁₆)}₂] (C₁₀H₁₆ = 2,7-dimethylocta-2,6-diene-1,8-diyl) (1) with two equivalents of the corresponding water-soluble phosphane. Reaction of 1 with one equivalent of the cage-type diphosphane ligand 2,3,5,6,7,8-hexamethyl-2,3,5,6,7,8-hexaaza-1,4- diphosphabicyclo[2.2.2]octane (THDP) allowed also the high-yield preparation of the dinuclear derivative [[RuCl₂(η³: η³-C₁₀H₁₆)}₂(μ-THDP)] (2f). All these new complexes have been analytically and spectroscopically (IR and multinuclear NMR) characterized. In addition, the structure of 2b, 2c, 2d, and 2 f was unequivocally confirmed by X-ray diffraction methods. Complexes 2a-f are active catalysts for the selective hydration of nitriles to amides in pure aqueous medium under neutral conditions. The wide scope of this catalytic transformation has been evaluated by using the most active catalysts [RuCl ₂(η³: η³-C₁₀H ₁₆)(THPA)] (2e) and [{RuCl₂(η³: η³-C₁₀H₁₆)}₂(μ-THDP)] (2f). Advantages of using MW versus conventional thermal heating are also discussed.