Structures and magnetic properties of three compounds from imidazolate-bridged copper(II) pyrazolylborate complexes

Three kinds of imidazolate-bridged copper(II) complexes using pz3BH anion as a capping ligand, namely, [Cu4(μ-im)4(pz3BH)4][Cu(pz3BH)2]2, [Cu4(μ-im)4(pz3BH)4] (Fig. left), and [Cu(μ-im)(pz3BH)]n (Fig. right) were afforded. The magnetic susceptibility measurements showed that the imidazole bridge played the role of an antiferromagnetic coupler. The Bonner-Fisher model with the Heisenberg spin Hamiltonian as H = −Σ 2JSi·Si+1 gave 2J/kB = −115.5(6) K for [Cu(μ-im)(pz3BH)]n. The magnitude of the present interaction belongs to the largest class, when compared with those of the known im-bridged copper(II) complexes.