The molecular structure of toluene

Discrepancies between two recently reported electron diffraction studies of toluene have provided the incentive for an ab initio structural determination at the 4-21 level. The methyl C-H bonds are on the average 0.011 Å longer than the ring C-H bonds. While the average ring C-C and C-H distances are nearly identical with those of benzene, the ring exhibits marked asymmetry, including an unexpected coupling between the ring C-C distances and the angle of methyl rotation.