Syntheses and crystal structures of 2-(-tol-yl)-1-perimidine hemihydrate and 1-methyl-2-(-tol-yl)-1-perimidine.

The title compounds, 2-(4-methylphenyl)-1-perimidine hemihydrate (, CHN·0.5HO) and 1-methyl-2-(4-methylphenyl)-1-perimidine (, CHN), were prepared and characterized by H NMR and single-crystal X-ray diffraction. The organic mol-ecule of the hemihydrate lies on a twofold rotation axis while the water mol-ecule lies on the inter-section of three twofold rotation axes (point group symmetry 222). As a consequence, the hydrogen atoms that are part of the N-H group and the water mol-ecule as well as the CH group of the -tolyl ring are disordered over two positions. In compound , the perimidine and the 2-aryl rings are slightly twisted while its -methyl-ated derivative has a more distorted conformation because of the steric repulsion between the -methyl group and the 2-aryl ring. In the crystal structures, mol-ecules of perimidine are held together only by C-H⋯π contacts while the parent perimidine does not exhibit this type of inter-action. Its crystal packing is established by inter-molecular N-H⋯O hydrogen bonds with the solvent water mol-ecules and additionally stabilized by π-π stacking.