Synthesis, reactivities and catalytic carbonylation of rhodium(I) carbonyl complexes containing isomeric acetylpyridine ligands

[Rh(CO)(2)Cl](2) reacts with two mole equivalent of 2-acetylpyridine (a), 3-acetylpyridine (b) and 4-acetylpyridine (c) to afford chelate [Rh(CO)Cl(eta(2)-N boolean AND O)] (1a) and non-chelate [Rh(CO)(2)Cl(eta(1)-N similar to O)] (1b, 1c) complexes, where, N boolean AND O = a, N similar to O = b, c. Oxidative addition (OA) of 1a-1c with CH3I and C2H5I yields penta coordinate rhodium(III) complexes, [Rh(COR) ClI(eta(2)-N boolean AND O)] {R = -CH3 (2a); -C2H5 (3a)} and [Rh(COR)(CO)ClI(eta(1)-N similar to O)] {R = -CH3 (2b, 2c); -C2H5 (3b, 3c)}. Kinetic study for the reaction of 1a-1c with CH3I indicates a pseudo-first order reaction. The catalytic activity of 1a-1c for the carbonylation of methanol to acetic acid and its ester was evaluated at different initial CO pressures 5, 10 and 20 bar at similar to 25 degrees C and higher turn over numbers (TON = 1581-1654) were obtained compared to commercial Monsanto's species [Rh(CO)(2)I-2] (TON = 1000) under the reaction conditions: temperature = 130 +/- 1 degrees C, pressure = 15-32 bar, rpm = 450, time = 1 h and catalyst: substrate = 1: 1900. (C) 2011 Elsevier B.V. All rights reserved.