Some physical and chemical aspects of spin trapping of organometallic radicals by quinones: optically active radical complexes

Abstract

A brief account is presented on the use of substituted quinones as spin traps for organometallic radicals and on the applications of CIDEP and esr–HPLC techniques to the study of quinone – organometallic radical complexes. Many of these radical adducts are thermally very stable and can be isolated by the HPLC technique for detailed spectroscopic and chemical studies. This in turn allows us to present a different approach to the "spin trapping" chemistry of unstable organometallic radicals by generating initially a stable quinone – metal carbonyl radical complex, separating the parent radicals by esr–HPLC and using them to react with other organometals via ligand exchange between the CO group(s) and the organometals. It then follows that if the entering organometal ligand is optically active, the substituted radical complex would also be chiral. This simple concept has led to the isolation of the first pure optically active radical complex with well-defined physical properties, including optical rotation.