The second stable conformation of the methoxy groups of o-dimethoxybenzene: stabilization of perpendicular conformation by CH–O interaction

Abstract

The conformational preference of the methoxy groups of o-dimethoxybenzene was analyzed by MP2/6-311G** level ab initio calculations. The two methoxy groups are coplanar in the most stable conformation. One methoxy group is nearly perpendicular in the second stable conformation. The calculated energy difference between the two conformations is only 0.16 kcal mol⁻¹, which indicates that the second methoxy group at the ortho position stabilizes the perpendicular conformation. The calculated structure suggests that CH–O interaction stabilizes the perpendicular conformation. Calculated charge distributions indicate that electrostatic interaction between the two methoxy groups increases the relative stability of the perpendicular conformation.