MNDO STUDY OF SOME IMIDAZOLE BASED BIHETEROCYCLES - A RATIONALIZATIONOF CENTRAL C-C BOND-LENGTH

MNDO geometry optimisations have been carried out on a series of bihet erocyclic compounds acting as ligating agents for different transition al and inner transitional metals involving imidazole and benzimidazole moieties. Their N-methylated and N, N'-dimethylated analogues have al so been taken for the MNDO geometry optimisation study. Remarkable con traction of C - C bond (inter-ring bond) has been observed for which e xplanation has been proposed. The heat of formation, the total energy of the molecules, the ionisation potential, the dipole moment of the m olecules as well as the net atomic charges on individual atoms of each molecule have been computed by MNDO study using full geometry optimis ation. These data give an insight to the electronic environment and ge ometry of the molecule. The change in the heats of formation of the is omers of each molecule has been correlated with their ligational behav iour.