Crystal structure analysis and strain-energy minimization calculations on a sterically crowded molecule: 1,8-dimethylnaphthalene

Abstract

The crystal structure of 1,8-dimethylnaphthalene has been solved by a reciprocal space-search method. Least-squares refinement of 914 independent X-ray reflections measured on a diffractometer leads to R 0·080. The molecular distortions caused by steric interaction of the methyl groups have been analysed by means of strain-energy minimization calculations, which show that the repulsive energy between the methyl groups is reduced mainly by bond-angle distortion at the junction between the methyl groups and the naphthalene nucleus. Crystals are monoclinic, space group P2₁/c, Z= 4, a= 9·835(3), b= 7·012(3), c= 16·115(5)Å, β= 124·35(3)°.