Spin–spin interactions in polynuclear nickel(II) complexes: susceptibility and low-temperature magnetisation studies of tris[bis(pentane-2,4-dionato)nickel(II)]

Abstract

The magnetic susceptibility and magnetisation of the trinuclear complex [Ni₃(pd)₆](pd = pentane-2,4-dionate) have been reinvestigated in the range 1.8–300 K. Detailed magnetisation studies have been performed to low temperatures to evaluate the properties of the septet (S= 3) ground state of the molecule. The results have been analysed in terms of the Heisenberg–Dirac–Van Vleck isotropic exchange Hamiltonian including contributions from single-ion zero-field splittings. Ferromagnetic coupling between adjacent ions is confirmed, although the magnitude of both this interaction and the antiferromagnetic interaction between the terminal ions is found to be half that previously reported. This diminution is due to the effect of zero-field splitting on the low-temperature magnetic properties, the ground-state septet (S= 3) having a splitting of –1.3 cm^–1.