sym-Hexahydropyrene.

In 1,2,3,6,7,8-hexahydropyrene, C16H16, the unsaturated rings lie essentially in a plane, the r.m.s. deviation of the atoms defining this plane form the best-fit plane being 0.006 (2) A. The saturated rings are substantially non-planar, but the character of the non-planarity of the saturated rings is quite different from that observed in octahydrochrysene. The C-C bond distances in the saturated rings are quite uniform, ranging from 1.505 (2) to 1.520 (2) A. No intermolecular distance is less than the sum of the corresponding van der Waals radii; closest approaches involve both C...H and H...H interactions.