Non-mutagenic organic pigment intermediates. II. Isomorphous 2,2'-dichloro-5,5'-dipropoxybenzidine and 2,2'-dimethyl-5,5'-dipropoxybenzidine.

The title compounds, C18H22Cl2N2O2 and C20H28N2O2, respectively, are isomorphous. The molecules lie at general positions in the unit cell. In each structure, chemically equivalent but crystallographically inequivalent amine N atoms exhibit different degrees of pyramidalization. The structures exhibit weak NÐH N hydrogen bonding, which is in ̄uenced by the differences in hybridization around the amine N atoms. The torsion angles across the biphenyl linkage for the two compounds are 67.2 (2) and 68.3 (3) .