Photochemical CCl bond activation of trichloroarenes by the rhenium complex (η5-C5Me5)Re(CO)3. X-ray structure of trans-(η5-C5Me5)Re(CO)2(2-methoxy-4,5-dichlorophenyl)chloride

Photochemical reaction of (η5-C5Me5)Re(CO)3, with 2,4,5-trichloroanisole and 3,4,5-trichlorotrifluoromethylbenzene yields (η5-C5Me5)Re(CO)2(C6H2Cl2(MeO))Cl (1) and (η5-C5Me5)Re(CO)2(C6H2Cl2(CF3))Cl, (2) formed by insertion of the fragment (η5-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), 1H-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 13C-NMR spectroscopies and supported by X-ray crystallography for 1.