Synthesis, crystal structure and magnetic properties of a new thiazolyl substituted nitronyl nitroxide and its copper(II) complexes

A new building block for molecule-based magnetic materials - thiazole-substituted nitronyl nitroxide NIT2-thz [1, NIT2-thz = 4,4,5,5-tetramethyl-2-(2'-thiazolyl)imidazolin-1-oxyl 3-oxide] and its copper(ii) complexes [Cu(NIT2thz)(2)(N-3)(2)] (2) and [CuCl2(NIT2-thz)(2)] (3) - have been synthesized and characterized structurally and magnetically. Compound I is found to contain two crystallographically independent molecules; the shortest contact between nitroxide groups is 4.900 Angstrom. Both 2 and 3 are mononuclear complexes, in which the copper(II) centers are hexacoordinate. In complex 2, the copper(II) ion has an elongated octahedral geometry, but complex 3 has a rare compressed-octahedral coordination sphere. Magnetic susceptibility data for compounds 1-3 have been measured in the range 5-300 K. There are ferromagnetic interactions (J = 10.13 cm(-1)) between the Cu-II ions and the radicals of 2, and antiferromagnetic interactions (J = -8.17 cm(-1)) between the Cull ions and the radicals of 3. The magnetic properties of complexes 2 and 3 are discussed in connection with their crystal structures. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).