Dicarbonylrhodium(I) complexes of benzoylpyridine ligands: Synthesis, reactivity and catalytic carbonylation reaction

The new complexes of the type [Rh(CO)(2)ClL] (1a-c), where L = 2-Benzoylpyridine (a), 3-Benzoylpyridine (b) and 4-Benzoylpyridine (c) have been synthesized and characterized. Oxidative addition (OA) of 1a-c with CH3I, C2H5I and C6H5CH2Cl afford penta coordinated Rh(III) complexes, [Rh(CO)(CORn)ClXL]{R-1 = -CH3 (2a-c), R-2 = -C2H5 (3a-c); X = I and R-3 = -CH2C6H5 (4a-c); X = CI}. Kinetic data for the reaction of 1a-c with CH3I indicate a pseudo-first order reaction. The la-c exhibit high catalytic activity in the carbonylation of methanol to acetic acid and its ester and show a higher turn over number (TON = 1529-1748) than the well known commercial species [Rh(CO)(2)I-2](-) (TON = 1000) under the reaction conditions: temperature 130 +/- 2 degrees C, pressure 30 +/- 2 bar and time 1 h. (C) 2009 Elsevier B.V. All rights reserved.