Photochemical C-Cl bond activation of trichloroarenes by the rhenium complex (eta(5)-C5Me5)Re(CO)(3). X-ray structure of trans-(eta(5)-C5Me5)Re(CO)(2)(2-methoxy-4,5-dichlorophenyl)chloride

Abstract

Photochemical reaction of (eta(5)-C5Me5)Re(CO)(3), with 2,4,5-trichloroanisole and 3,4,5-trichlorotrifluoromethylbenzene yields (eta(5)- C5Me5)Re(CO)(2)(C6H2Cl2(MeO))Cl (1) and (eta(5)-C5Me5)Re(CO)(2)(C6H2Cl2(CF3))Cl, (2) formed by insertion of the fragment (eta(5)- C5Me5)Re(CO)(2) into the C-Cl bond of the chloroarenes. The C-Cl bond activation of trichloroanisole occurs at the chlorine ortho respect to the methoxy group as revealed by the X-ray structure of 1. In the case of the reaction with C6H2Cl3(CF3), H-1-NMR spectroscopy indicates that only the C-Cl bond meta respect to CF3 group is cleaved. Complex 1 was isolated as the trans isomer while 2 was obtained as an isomeric mixture (trans-2 and cis-2). The stereochemistry of these complexes has been assigned by IR and C-13-NMR spectroscopies and supported by X-ray crystallography for 1.