SCF-MO COMPUTATIONAL ANALYSIS OF THE GEOMETRIC CONFORMATION AND CHARGE-DISTRIBUTION IN PICRIC ACID AND ALKALI PICRATE SALTS

SCF-MO computations were employed in a study of picric acid, the -1 pi crate ion, and Li, Na, and K picrates. Atomic coordinates from crystal lographic structural analyses were used as initial parameters in the c omputation of the minimum-energy conformations of each free molecule a t the 6-31G level. The Mulliken charge numbers for each atom in the op timized model molecules were calculated at the 6-31G* level. The indu ction and resonance effects of the OX group (X = H, Li, Na, K) on the trinitrophenyl ring are discussed. It is demonstrated that molecular ( electron) isodensity surfaces (MIDCOs) describe charge-density results nicely compatible with the point Mulliken charge numbers.