Spin–orbit coupling and d2–d2 interactions in dinuclear bioctahedral metal clusters

The electronic structure and the metal–metal d2–d2 interactions in dinuclear bioctahedral face-shared cluster complexes [M2X9]3− (M = V, Nb, Ta, and X = Cl, Br, I) have been studied with DFT and topological methods QTAIM and ELF. The ground states of the complexes are shown to be spin-paired and nonmagnetic only in the approximation of spin–orbit interaction. The result correlates well with experimental data on magnetic susceptibility for solid-state complexes containing [Nb2X9]3− and [Ta2X9]3− anions as well as for [V2X9]3− anions in low-temperature spin-paired modifications of Cs3V2Cl9 and Rb3V2Br9 complexes. The transition to the high-temperature spin-paramagnetic state of [V2X9]3− anions is shown to be related to the bifurcation of d2–d2 interaction at some critical distance DCR(M–M) and to weakening of spin–orbit coupling in divanadium complexes.

How spin–orbit interaction, magnetic properties and meta–meta distance are interrelated in bioctahedral face-shared cluster complex [M2X9]3− (M = V, Nb, Ta, and X = Cl, Br, I).Figure optionsDownload as PowerPoint slide