Theoretical study of intermolecular spin alignments through hydrogen bonding of the carboxy group

Intermolecular magnetic interactions through hydrogen bonding of the carboxy group for dimers of allyl, benzyl, and chlorinated benzyl radicals have been investigated as model systems by the ab initio molecular orbital (MO) and density functional theory (DFT) calculations. It is found possible to propagate magnetic interaction through hydrogen bonding, although the effect is small. The spin densities of π- and σ-electrons have shown that antiferromagnetic coupling exists between the two intermolecular oxygen atoms in the ground state. This behavior is consistent with McConnell’s model, being applied to the planar configuration of the two hydrogen-bonded carboxy groups.