Structure of s-cis or E Benzoic Acid

This is the RHF/6-31G* optimized structure of s-cis or E benzoic acid. The structure shown has the H-atom and the phenyl group on the same side of the C-O single bond. Hence the structure is referred to as s-cis. In the E/Z-nomenclature, the structure shown is E because H and O are the high priority substituents on the atoms of the C-O bond and they are on opposite sides (entgegen). Note that the carboxy group is twisted out of the plane of the benzene! What might be the reason for this feature?


Figure. The RHF/6-31G* optimized structure of s-cis or E benzoic acid.

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