Synthesis, crystal structures, and magnetic properties of nitroxide radical-coordinated manganese(II) and cobalt(II) complexes

Abstract

Coordination complexes constructed from the nitronyl nitroxide radical NIT-Pyra-3-Isobu and MII(hfac)2(H2O)2 as building blocks (NIT-Pyra-3-Isobu = 2-(3-isobutyl-pyrazole)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, hfac = hexafluoroacetylacetonato, and M = Mn or Co) are successfully synthesized. The crystal structures of the coordination compounds reveal the usefulness of the functionalized radical in providing discrete or extended architectures. Single-crystal X-ray diffraction analyses indicated that the ligand is coordinated through the oxygen atom of NO• and the N atom of the pyrazole linkage to the metal, and the metals adopt an octahedral geometry leading to one-dimensional zig-zag chain systems. The magnetic behavior of the manganese and cobalt shows overall antiferromagnetic interactions between the metal center and the organic radical.