Spin–spin interactions in polynuclear nickel(II) complexes: a susceptibility and low-temperature magnetisation study of the linear trimer hexakis(allylamine)hexakis-µ-benzotriazolyl-trinickel(II)–triphenylphosphine oxide (1/2)

Abstract

The linear title compound [Ni{Ni(N₃C₆H₄)₃[N(C₃H₅)H₂]₃}₂]·2PPh₃O has been studied using bulk magnetic susceptibility and magnetisation measurements in the range 2.0–300 K. The molecule has been found to have a spin-triplet ground state from an analysis of the high-temperature (>4.2 K) data and confirmed by the low-temperature (16–1.8 K) magnetisation results. The magnetic susceptibilities have been interpreted in terms of the Heisenberg–Dirac–Van Vleck isotropic exchange Hamiltonian. An antiferromagnetic interaction (J= 10 cm^–1) occurs between adjacent atoms bridged by the benzotriazolyl molecules, and a small ferromagnetic interaction between the terminal ions. The mechanism of these interactions is discussed and compared with those found in similar molecules.