The crystal structure of 10-dicyanomethyleneanthrone, an overcrowded aromatic compound

Abstract

The crystal structure of 10-dicyanomethyleneanthrone has been determined by three-dimensional X-ray analysis to an accuracy of 0·01 Å in the orthogonal atomic co-ordinates. The structure is orthorhombic, space group Pnam, with four molecules in a cell of dimensions a= 7·52, b= 8·84, c= 18·02 Å. A clearance of 2·84 Å between overcrowded carbon atoms is achieved by means of angular adjustments and by deformations out-of-plane. The configuration, which closely resembles that in bianthronylidene, involves a bend of 28° in the anthracene skeleton, a dihedral angle of 144° between the planar dicyanomethylene group and the anthracene framework, and a twist or non-parallelism of 5° out-of-plane between the direction defined by the 9,10 carbon atoms and corresponding directions in the outer rings.