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 (N 3 ) 2 ] ( 2 ) and [CuCl 2 (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 Cu II ions and the radicals of 2 , and antiferromagnetic interactions ( J = −8.17 cm −1 ) between the Cu II 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)