Synthesis of New Ruthenium-CAP Complexes and Use as Catalysts for Benzonitrile Hydration to Benzamide

The new bimetallic [Ru2(mu-Cl)3(CAP)6]Cl (1) and monometallic cis,cis,trans-[RuCl2(dmso)2(CAP)2] (2) complexes, bearing the water soluble cage-like phosphine CAP (1,4,7-triaza-9-phosphatricyclo[5.3.2.1]tridecane), were synthesized and characterized in solution by NMR spectroscopy and ESI-MS spectrometry. The complexes, endowed with high solubility and stability in water, were applied as catalysts for the proof-of-concept hydration of benzonitrile to benzamide in neat water at 100 °C, achieving high conversions with only 1 mol% of catalyst, both in single runs and in catalyst recycling experiments.