Dicarbonylrhodium(I) complexes of aminophenols and their catalytic carbonylation reaction.

Abstract

The complexes [Rh(CO)2CIL](1), where L = 2-aminophenol (a), 3-aminophenol (b) and 4-aminophenol (c), have been synthesized and characterized. The ligands are coordinated to the metal centre through an N-donor site. The complexes 1 undergo oxidative addition (OA) reactions with various alkyl halides (RX) like CH3I, C2H5I and C6H5CH2Cl to produce Rh(III) complexes of the type [Rh(CO)(COR)XCIL], where R = -CH3(2), -C2H5(3), X = I; R = C6H5CH2- and X = Cl (4). The OA reaction with CH3I follows a two-stage kinetics and shows the order of reactivity as 1b > 1c > 1a. The minimum energy structure and Fukui function values of the complexes 1a-1c were calculated theoretically using a DND basis set with the help of Dmol3 program to substantiate the observed local reactivity trend. The catalytic activity of the complexes 1 in carbonylation of methanol, in general, is higher (TON 1189-1456) than the species [Rh(CO)2I2]- (TON 1159). Show more