title: Ab initio MO analysis of interaction paths between radicals in ferromagnetic organic systems.
abstract: Interaction path analyses for pi-conjugated organic systems were performed at the ab initio molecular orbital level to examine the relationship between inter-radical interactions and the high-spin stability of the system. It was found that the high-spin stability results from through-bond interactions between radicals, not from through-space interactions, in relation to the stabilization of a low-spin state due to the effects of electron correlation. L(ij)(min) value for estimating the mixing of nonbonding molecular orbitals well predicted the relationship between the through-bond interactions and the high-spin stability. Furthermore, molecular orbital calculations revealed that the all-trans type interaction path between radicals produces long-range exchange interactions, and the additivity of high-spin stability is observed by keeping short-range through-bond interaction paths.
authors.affiliation: Department of Material Sciences, Faculty of Engineering Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Yuuichi
authors.initials: Y
authors.lastname: Orimoto
authors.forename: Takahiro
authors.initials: T
authors.lastname: Imai
authors.forename: Kazunari
authors.initials: K
authors.lastname: Naka
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Aoki