Angular group-induced bond alternation (AGIBA). Part 5 - Conformation dependence and additivity of the effect: structural studies of 3,5-dimethoxybenzaldehyde derivatives and related systems

X-ray structure analysis of 3,4,5-trimethoxybenzadehyde and 3,5-dimethoxy-4-(1-bromoethoxy)benzaldehyde gave their molecular geometries which showed a vague AGIBA effect. To clarify the situation, nb initio optimizations at the MP2/6-31G**: level of theory of 12 conformers of 1,3,5-trimethoxy-, 1,3-dimethoxy-5-formy-1,3-diformyl-5-methoxy- and 1,3,5-triformylbenzene derivatives were carried out. The results support the occurrence of additive AGIBA effects, even if some weak interactions are possible between the methoxy and formyl groups. Copyright (C) 2001 John Wiley & Sons, Ltd.