A metastable polymorphic form of the antifungal anilinopyrimidine active Pyrimethanil

Abstract

A second, metastable form of the title compound, C~12~H~13~N~3~ (systematic name: 4,6-dimethyl-N-phenylpyrimidin-2-amine), was isolated from an attempted cocrystallization experiment with <i>meso</i>-erythriol in dimethylsulfoxide (DMSO). The crystals of form 2 at 120 K are monoclinic, space group <i>P</i>2~1~/<i>n</i> with <i>Z'</i> = 4 compared to the previously reported triclinic form with Z' = 2 [Sun <i>et al.</i> (2011). <i>Acta Chim. Sinica</i> <b>69</b>, 1909-1914]. The four independent molecules in the asymmetric unit form two discrete dimeric units through a concerted pair of N---H...N hydrogen bonds with a graph set notation of <i>R</i>^2^~2~(8). The origin of the polymorphic behaviour is revealed in that the conformation of each dimer present in the asymmetric unit of the structure is unique and determined by the rotation of the second molecule in the dimer with respect to the first.