A metastable polymorphic form of the antifungal anilinopyrimidine active Pyrimethanil

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 meso-erythriol in dimethylsulfoxide (DMSO). The crystals of form 2 at 120 K are monoclinic, space group P2~1~/n with Z' = 4 compared to the previously reported triclinic form with Z' = 2 [Sun et al. (2011). Acta Chim. Sinica 69, 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 R^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