Substantial inverse isotope effects in the hydrogen atom abstraction from [(L)ClRh^III-H/D]⁺ macrocyclic complexes by methyl radicals in aqueous solutions

Substantial inverse isotope effects in the hydrogen atom abstraction from [(L)ClRh^III-H/D]⁺ macrocyclic complexes by methyl radicals in aqueous solutions were studied. All solutions were prepared from analytical grade chemicals and distilled water that was passed through a Millipore setup, the final resistance being above 10 Mωcm^-1. The trans and cis- [(L)ClRh^III-H]⁺ complexes were synthesized. Gas chromatography analysis was performed on a HP 5890 gas chromatograph on a pack Q column with FID and TCD detectors. It was concluded that methyl radicals abstract an hydrogen atom and not a chlorine atom from [(L)ClRh ^III(H₂O)}⁺. The results suggest that the mechanism of hydrogen abstraction from M-H groups might differ considerably from C-H groups.