Molecular structures of dinitroanilines and trinitroanilines

The molecular structures of six positional dinitroaniline isomers and six p ositional trinitroaniline isomers were calculated by a density functional t heory of the Becke's three-parameter hybrid (B3LYP) method with 6-31G* basi s set. Calculations found that deformations of the phenyl ring and distorti ons of the nitro and amino groups with the phenyl ring of each isomer were different. Deformations of the phenyl ring do not completely match the rule predicted by Domenicano and co-workers. Except for the inductive and reson ance effects, the steric effects also play an influential role in the defor mation of the phenyl ring and the distortion of the substitution groups wit h the ring. Calculated energies indicated that for dinitroanilines, 2,4-din itroaniline and 2,6-dinitroaniline are the favored molecules while 2,3-dini troaniline and 3,4-dinitroaniline are the unfavored ones; for trinitroanili nes, 2,4,6-trinitroaniline is the most favored molecule and 3,4,5-trinitroa niline is the most unfavored one, For some isomers having an intramolecular hydrogen bonds as the C-NO...HN-C type, it is generally stronger than nitr otoluene isomers which have the C-NO...HC-C type of intramolecular hydrogen bonds. (C) 1994 Elsevier Science Ltd. All rights reserved.