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

The new complexes of the type [Rh(CO)2ClL] (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]{R1 = -CH3 (2a–c), R2 = –C2H5 (3a–c); X = I and R3 = –CH2C6H5 (4a–c); X = Cl}. Kinetic data for the reaction of 1a–c with CH3I indicate a pseudo-first order reaction. The 1a–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)2I2]− (TON = 1000) under the reaction conditions: temperature 130 ± 2 °C, pressure 30 ± 2 bar and time 1 h.

The three new Rh(I) carbonyl complexes of the type [Rh(CO)2ClL]; L = 2-Benzoylpyridine, 3-Benzoylpyridine and 4-Benzoylpyridine have been synthesized, which undergo oxidative addition (OA) with different electrophiles such as CH3I, C2H5I, and C6H5CH2Cl. These complexes show higher catalytic activity (TON = 1529–1748) in carbonylation of methanol than well known Monsanto's species [Rh(CO)2I2]− (TON = 1000).Figure optionsDownload high-quality image (13 K)Download as PowerPoint slide