Crystal structure of 1,2-bis­[(2-tert-butyl­phen­yl)imino]­ethane

The whole molecule of the title compound, C(22)H(28)N(2), (I), is generated by inversion symmetry. The mol­ecule is rather similar to that of 2,3-bis­[(2-tert-butyl­phen­yl)imino]­butane, (II), a di­imine ligand comprising similar structural features [Ferreira et al. (2006 ▸). Acta Cryst. E62, o4282–o4284]. Both ligands crystallize with the –N=C(R)—C(R)=N– group around an inversion centre, in a trans configuration. Comparing the two structures, it may be noted that the independent planar groups in both mol­ecules [the central link, –N=C(R)—C(R)=N–, and the terminal aromatic ring] subtend an angle of 69.6 (1)° in (II) and 49.4 (2)° in (I). Ferreira and co-workers proposed that such angle deviation may be ascribed to the presence of two non-classical intra­molecular hydrogen bonds and steric factors. In fact, in (I), similar non-classical hydrogen bonds are observed, and the larger angular deviation in (II) may be assigned to the presence of methyl groups in the di­imino fragment, which can cause steric hindrance due to the presence of bulky tert-butyl substituents in the aromatic rings. The C=N bond lengths are similar in both compounds and agree with comonly accepted values.