MOLECULAR-STRUCTURES OF 2 3-PYRAZOLIDONE COMPOUNDS WITH POTENT ANTICONVULSANT ACTIVITY

The crystal and molecular structures of two potent anticonvulsant comp ounds:1 - (n - butyl) - 5 - (p - fluorophenyl) - 3 - pyrazolidone(1) a nd 1 - (n - propyl) - 5 - (p - methylphenyl) - 3 - pyrazolidone(2) wer e determined by X - ray diffraction method. The atomic net charges wer e calculated by CNDO/2 method. It is shown that the bond lengths of C- N and C-O of the conjugated amido groups and the atomic net charges in the five membered rings of 3 - pyrazolidones are affected by the elec tronreleasing capabilities of R(1) groups. It is considered that a sub stituent being more electron - releasing at position 1 of the five mem bered ring of 3 pyrazolidone is favorable on enhancement of the antico nvulsant activity, and the substituent at position 5 might mainly affe ct the molecular steric shape and the hydrophobic property.