C-H···O and C-H···N hydrogen bond networks in the crystal structures of some 1,2-dihydro-N-aryl-4,6-dimethylpyrimidin-2-ones

Abstract

A set of three aryl dimethyl pyrimidinones have been studied and their crystal structures described in terms of networks of C-H···O and C-H···N hydrogen bonds. Two of the three molecules in this study differ in the replacement of a chloro group by a methyl group and obey the chloro - methyl exchange rule in that they have nearly identical crystal structures. However, and in contrast to other pairs of compounds so related, the chloro and methyl groups here are not merely isosteric but also form similar polarization-induced Cl···Ph and CH3···Ph contacts. These conjugated molecules may offer some scope for nonlinear optical studies. (C) 2000 Academic Press.