study of the structural and electronic properties of valproic acid and new derivatives used as anticonvulsant agents the conformational and electronic characteristics of the polar o9c8x10 moiety in the anticonvulsant valproic acid vpa drug and some of their amides and ester derivatives are analyzed at the b3lyp level using the 631gdp and 6311gdp 6d10f basis sets exploring the delocalization of the electron density of the o9c8x10 moiety by means of elf nbo and aim calculations we found that the bending away from coplanarity of the atoms in o9c8x10 is accompanied by a threedimensional arrangement of donor and acceptor proton units closing nearly planar pseudorings of four five and six members arising from stabilizing interactions around the o9c8x10 backbone from the structureproperty relationship analysis we explain the origin of the change in the structural parameters and atomic charges in the polar moiety