A benzyl–carbon bond dissociation energy of one-third the normal value: a quantitative study of benzyl–carbon bond homolysis in [CoIII(L2–CH2Ph)I], a cobalt-to-carbon benzyl migration product derived from the coenzyme B12model complex [CoIII(L1)(CH2Ph)I

Abstract

Benzyl–carbon bond thermal homolysis studies using the TEMPO radical-trapping method reveals a low benzyl–carbon bond dissociation energy (BDE) in [CoIII(L2–CH2Ph)I] of 25 ± 3 kcal mol–1, a value one-third the normal BDE of ca. 76 kcal mol–1 and approximately equal to the cobalt–carbon homolytic BDE in the parent complex [CoIII(L1)(CH2Ph)I]; such little-documented low BDEs relate back to Gomberg's classic example of Ph3C–C6H5CPh2 and its ca. 11 kcal mol–1 carbon–(p-phenyl)carbon BDE (1 cal = 4.184 J).