A magnetostructural study of linear (NiMnNiII)-Mn-II-Ni-III, (NiCrNiII)-Cr-II-Ni-III and triangular Ni-3(II) species containing (pyridine-2-aldoximato) nickel(II) unit as a building block

摘要

Three trinuclear complexes, (NiMnNiII)-Mn-II-Ni-III 1, (NiCrNiII)-Cr-II-Ni-III 2 and Ni-3(II) 3 based on (pyridine-2-aldoximato)nickel(II) units are described. Two of them, 1 and 2, contain metal-centers in linear arrangement, as is revealed by X-ray diffraction. Complex 3 is a homonuclear complex in which the three nickel( II) centers are disposed in a triangular fashion. The compounds were characterized by various physical methods including cyclic voltammetric and variable-temperature (2-290 K) susceptibility measurements. Complexes 1 and 3 display antiferromagnetic exchange coupling of the neighbouring metal centers, while weak ferromagnetic spin exchange between the adjacent Ni-II and Cr-III ions in 2 is observed. The experimental magnetic data were simulated by using appropriate models.