Two new nitronyl nitroxide Cu(II) complexes {[Cu(hfac)2]2(NIT-4PyPh)}2(1) and [Cu(hfac)2][(NIT-3PyPh)2](2)(NIT-4PyPh=2-[4-(4-pyridinylmethoxy)
phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide,NIT-3PyPh=2-[4-(3-pyridinylmethoxy)phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide,hfac=hexafluoroacetylacetone), have been synthesized and characterized. The X-ray crystal structure analyses show that structures of the two complexes are different. Complex 1 crystallizes in cyclic metal-radical dimer consisting of four Cu(hfac)2 and two NIT-4PyPh ligands; four Cu(II) atoms adopt two coordinated modes. In the ring, each Cu(II) ion is hexa-coordinated by four oxygen atoms of two hfac ligands and one oxygen atom (ONCNO) and one nitrogen atom of the pyridinyl group from two different radicals. Outside the ring, each Cu(II) is penta-coordinated by four oxygen atoms of two hfac ligands and one oxygen atom (ONCNO) from the radical ligand. Complex 2 crystallizes in discrete molecule, while the Cu(II) atom is hexa-coordinated by four oxygen atoms of two hfac molecules and two nitrogen atoms of the pyridinyl group from two radical ligands.
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