Synthesis, crystal structure and magnetism of two cobalt(II) complexes with imino and nitronyl nitroxides

Two new cobalt–radical complexes, namely [Co(IM-5-Br-2Py)2(N3)2]·MeOH (1) and [Co(NIT-5-Br-2Py)2(N3)2] (2) (IM-5-Br-2Py = 2-(5-bromo-2-pyridyl)-4,4,5,5-tetramethyl-limidazoline-1-oxyl, NIT-5-Br-2Py = 2-(5-bromo-2-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) have been synthesized and characterized by magnetic and single-crystal X-ray diffraction studies. X-ray diffraction analysis indicates that both complexes possess mononuclear structures, in which two radical ligands coordinate to the Co(II) atom in chelating fashion and two azides act as terminal ligands. The magnetic properties for complexes 1 and 2 have been investigated in the temperature range 2–300 K. DC magnetic measurements show that the Co(II) atom of complex 1 interacts ferromagnetically with the directly bonding imino nitroxide, while the Co(II) atom strongly antiferromagnetically couples with the directly coordinated N–O group in complex 2.