Preparation, Hydrogen Bonds, and Catalytic Activity in Metal-Promoted Addition of Arylboronic Acids to Enones of a Rhodium Complex Containing an NHC Ligand with an Alcohol Function

The complex RhCl­(COD)­{3-benzyl-1-(2-hydroxy-2-phenylethyl)­imidazol-2-ylidene} has been prepared by reaction of the dimer [Rh­(μ-OMe)­(COD)]2 with 3-benzyl-1-(2-hydroxy-2-phenylethyl)­imidazolium chloride and characterized by X-ray diffraction analysis. The structure reveals that 75% of the molecules are associated through intermolecular O–H···Cl hydrogen bonds between the OH group of the NHC substituent of one molecule and the chloride ligand of the adjacent molecule. This complex catalyzes the addition of arylboronic acids to cyclic and acyclic enones in anhydrous toluene. The alcohol function of the substituent of the NHC ligand plays the role assigned to water in previous cases.