A novel functional nitronyl nitroxide and its copper and cobalt complexes: Synthesis, structures and magnetic properties

Four new metal complexes derived from a functional nitronyl nitroxide ligand, 2-(6-bromo-3-pyridyl)-4,4,5,5tetramethyl-imidazoline-1-oxyl-3-oxide (NIT-6Br-3Py) and M(hfac) 2+ (M 2+ = Cu 2+ , Co 2+ ; hfac = hexafluoroacetylacetonate), [(Cu(hfac) 2 ) 3 (NIT-6Br-3Py) 2 ] ( 1 ), [Cu(hfac) 2 NIT-6Br-3Py] n ( 2 ), [Co(hfac) 2 (H 2 O)NIT- 6Br-3Py] ( 3 ) and [(Co(hfac) 2 ) 2 (NIT-6Br-3Py) 2 ] ( 4 ) have been synthesized and characterized. In complex 1 , the NIT-6Br-3Py ligand acts as bridging ligand to link three Cu(II) ions leading to {Cu 3 } complex while complex 2 displays a 1D-chain structure. Complex 3 possesses mono-nuclear structure and 4 is a four-spin complex with a dimeric structure, where the NIT-6Br-3Py ligand links Co ions via the oxygen atom of NO group and the nitrogen atom from pyridine ring. Magnetic studies show that the antiferromagnetic interactions are dominated in complexes 1 , 3 and 4 , while there exist strong ferromagnetic interactions between Cu II and coordinated nitronyl nitroxide radical ligand in complex 2 .