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(NIT2‐thz)2(N3)2] (2) and [CuCl2(NIT2‐thz)2] (3) — have been synthesized and characterized structurally and magnetically. Compound 1 is found to contain two crystallographically independent molecules; the shortest contact between nitroxide groups is 4.900 Å. 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 CuII ions and the radicals of 2, and antiferromagnetic interactions (J = −8.17 cm−1) between the CuII ions and the radicals of 3. The magnetic properties of complexes 2 and 3 are discussed in connection with their crystal structures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)