SYNTHESIS OF FUSED PERIMIDINIUM DERIVATIVES AND INVESTIGATION OF THEIR STRUCTURE BY AB-INITIO CALCULATIONS

A series of perimidinium salts have been prepared by N-alkylation and N-amination methods. These salts were condensed with 1,2-dicarbonyl co mpounds and quinones (Westphal condensation) to produce pyridazino[2,3 -a]perimidinium and, in one case, pyrido[2,3-a]perimidinium derivative s. Two of these heteroaromatic cations were studied by ab initio calcu lations at the SCF (self-consistent field) level using different basis sets. From Mulliken population analysis and geometrical consideration s, it is predicted that the pyrrole-like nitrogen of the perimidinium moiety is lying out of the planarity, thus reducing the interaction wi th the fused pyridazinium ring.