Theoretical study of CH bond dissociation energies of HC(X)R {XÂ =Â O, S, Se; RÂ =Â H, CH3, Cl, NH2}

CH bond dissociation for the molecule HC(X)R {X = O, S, Se; R = H, CH3, Cl, NH2} have been studied at various theoretical levels. Studies indicate that CH BDE increases in the order of X as O < S < Se for R = H, CH3 and Cl. Results also indicate that CH BDE's for substituted formaldehyde and its thio- and seleno-analogs have 7-16 kcal/mol BDE less than that of methane at G2MP2 theoretical level indicating magnificent stabilization of HC(X) radical by CX group. The radical stabilization energy relative to HC(X)H infer smaller variation in BDE due to substituent effect.