Molecular magnetic properties of heteroporphyrins: a theoretical analysis.

B3LYP/6-31G(d) optimization of porphyrin, tetraphenylporphyrin and their 21,23-diheteroatom substituted derivatives with O, S, and Se heteroatoms was performed. A planar macrocycle was found in all cases except 21,23-dioxatetraphenylporphyrin which presents only slight deviations from planarity. A Bader analysis uncovers the presence of S-S and Se-Se interactions in the four corresponding heteroporphyrins, which appreciably distort the original unsubstituted macrocycles.

Formation of trichlorinated dibenzo-p-dioxins from 2,4-dichlorophenol and 2,4,5-trichlorophenolate: a theoretical study.

The reaction of the 2,4,5-trichlorophenolate anion with 2,4-dichlorophenol to afford trichlorinated dibenzo-p-dioxins (T3CDDs) is investigated at the B3LYP/6-31+G(d) and B3LYP/6-311+G(3df,2p)//B3LYP/6-31+G(d)+ZPVE(B3LYP/6-31+G(d)) levels of theory. The first stage of the process corresponds to the formation of a predioxin, which can evolve through four different routes. Two of them lead directly to the products 2,3,7-T3CDD and 1,3,8-T3CDD, and the other two afford different predioxin-type intermediates, which in turn can evolve through all or some of the four routes to give new predioxins or T3CDD.