Radical Stabilization Energies of Substituted XNH¥ Radicals

摘要: The performances of a number theoretical methods in the calculation N-H bond dissociation energies and radical stabilization associated with X-NH° radicals were examined. It was found that UHF, UMP2, UMP4 not reliable for nitrogen because spin contamination suffered by them. Surprisingly, ROHF, ROMP2, ROB3LYP to be either, they could lead unrealistic spin-localization radical. This even seen UCCSD(T) method. only credible modest-level method UB3LYP, which provide at least qualitatively correct radicals. basis set effect on UB3LYP also very small. Nevertheless, G3 CBS-Q able fairly accurate substituted According results, CH 3 , NH 2 OH, F, Cl, CN assigned stabilizing substituents radical, as these groups effectively delocalize odd electron By contrast, COCH CONH COOH, CHO destabilizing although origin destabilization loss conjugation between lone-pair electrons substituent from neutral X-NH molecule