Condensation reactions of aromatic aldehydes with acetone for carbon-carbon bond formation are catalysed by magnesium carboxylate complexes. Two magnesium complexes having compositions [(4-NO2-C6H4CO2)(2)Mg(CH3OH)(4)] (1) and [(4-CH3-C6H4CO2)(2)Mg(CH3OH)(2)(H2O2)] (2) that are catalysts for such reactions are synthesized. They are prepared by reacting metallic magnesium With methanol in the presence of 4-nitrobenzoic acid and 4-methylbenzoic acid. respectively. structures of 1 and 2 are determined by X-ray crystallography. The catalytic reactions of these two complexes for carbon-carbon bond formation reactions of various aromatic aldehydes with acetone ate presented. (C) 2009 Elsevier B.V. All rights reserved.