Synthesis, Structure and Magnetic Property of a New Cobalt (II) Complex Based on Pyridyl-substituted Imino Nitroxide Radical

Abstract

A new cobalt(II)–radical complex: [Co(im4-py)2(PNB)2] (im4-py = 2-(4'-pyridyl)-4,4,5,5-tetramethylimidazole-1-oxyl, PNB = p-nitrobenzoic acid anion) has been synthesized and characterized by X-ray diffraction analysis, elemental analysis, IR and magnetic properties. X-ray analysis reveals that the complex crystallizes in monoclinic system, space group C2/c with a = 34.001(4), b = 6.3444(7), c = 24.615(3) Å, α = 90, β = 133.676(2), γ = 90°, V = 3840.4(8) Å3, Z = 8, Mr = 413.86, Dc = 1.432 g/cm3, μ = 0.516 mm-1, F(000) = 1724, the final GOF = 1.060, R = 0.0641 and wR = 0.1514 for 2660 observed reflections with I > 2σ(I). X-ray diffraction analysis shows that the complex is four coordinated with tetrahedron geometry, where the Co(II) ion is located in the central site of the tetrahedron, two radicals and two PNB ligands are trans-coordinated to the Co(II) ion. The magnetic susceptibility study indicates the complex exhibits weak ferromagnetic interactions between cobalt(II) and im4-py radical. The magnetic property is explained by the structure and a magnetic exchange mechanism.