The para-didehydropyridine, para-didehydropyridinium, and related biradicals - a contribution to the chemistry of enediyne antitumor drugs

Structure and stability of seven singlet (S) biradicals formed by Bergman cyclization from enediynes are investigated with unrestricted DFT using B3LYP/6-31G(d,p) and B3LYP/6-311+G(3df,3pd). The corresponding triplets (T) are also calculated and compared with their S states utilizing the on-top pair density and the S-T difference on-top pair density. A… CONTINUE READING