Peri interactions: an X-ray crystallographic study of the structure of 1,8-bis(dimethylaminonaphthalene)

Crystals of 1,8-bis(dimethylamino)naphthalene, C_(14)H_(18)N_2, are orthorhombic, space group P2_12_12_1, with ɑ= 12•855 (1), b= 10•110 (1), c=9•664 (1)Å and Z=4. A complete structure determination, including refinement of the positions of the hydrogen atoms, led to an R index of 0-053 and a goodness-off-it of 2.02 for 1477 reflections. The molecule adopts a conformation in which one carbon atom of each of the dimethylamino groups is eclipsed with respect to the naphthalene ring. Hindrance between the dimethylamino groups and/or resonance interactions between the dimethylamino groups and the aromatic ring are sufficiently great to distort the ring in several ways, the most conspicuous being a sizable increase in the non-bonded C(1)••• C(8) distance (2.56 Å) compared to the C(4)••• C(5) distance (2•44 A) and a twisting of the naphthalene ring into a considerably nonplanar conformation.