Quantum Theory of Atoms in Molecules (QTAIM) analysis on B3LYP/6-311++G(2d,2p) 6d electron densities of five benzyl derivatives (C(6)H(5)-CH(2)X; X = F, Cl, OH, SH, NH(2)) and seven related fluorides of furan, pyrrole, and naphthalene indicates that the preference for perpendicular or gauche conformation exhibited by these compounds is related to the diminution of the steric repulsion between the heteroatom at the substituent and the closest hydrogen in the ring. The electron density reorganization can be satisfactorily explained on the basis of these repulsive interactions, while no evidence of larger hyperconjugative delocalization is observed in the preferred conformations.
Benzyl Compounds Electrons