Synthesis, Crystal Structure and Magnetic Properties of Cobalt(II) Complex Involving Imino Nitroxide Radicals

A novel compound [Co(IM2-Py)2(NO3)]?(NO3) (IM2-Py = 2-(2?-pyridyl)-4,4,5,5- tetramethylimidazoline-1-oxyl) has been prepared and structurally characterized by X-ray diffrac- tion method. It crystallizes in orthorhombic, space group P212121 with a = 11.031(2), b = 13.492(3), c = 20.467(4) ?, V = 3046.0(11) ?3, C24H32CoN8O8, Mr = 619.51, Z = 4, Dc = 1.351 g/cm3, μ(MoKα) = 0.620 mm?1, F(000) = 1292, R = 0.0506 and wR = 0.0845 for 3752 observed reflections with I > 2σ(I). X-ray analysis reveals that the crystal structure consists of [Co(IM2- Py)2(NO3)]+ moiety and a NO3 anion. The cobalt(II) ion is six-coordinated with a distorted octahedral geometry. Tempera- ? ture dependence of susceptibility measurements show that there exist an antiferromagnetic inter- action in the compound.

Synthesis and Uncommon Structural Characterization of Novel Zinc and Cadmium Complexes with Imino Nitroxide Radical

Two novel complexes {[Zn（IM4py）2（tp）（H2O）]2H2O}. 1 and {[Cd（IM4py）2（tp）- （H2O）]1.25H2O},, 2 （IM4py = 2-（4＇-pyridinyl）-4,4,5,5-tetramethylimidazoline-l-oxyl and tp = terephthalate dianion） have been synthesized and characterized by elemental analyses, IR spectrum and single-crystal X-ray diffraction. Crystal data for complex I： monoclinic, space group C2/c, a = 20.648（7）, b = 12.130（4）, c = 14.036（4） A, β = 106.351（5）°, C32H42N6O9Zn, Mr = 720.09, V = 3373.3（2） A3, Z= 4, Dc = 1.418 g/cm^3μt（MoKα） = 0.790 mm^-1, F（000） = 1512, the final R = 0.0407 and wR = 0.0894 for 3480 independent reflections with Rint = 0.0432. Crystal data for complex 2： monoclinic, space group C2/c, a = 21.332（6）, b = 12.063（3）, c = 14.246（4） A, β = 106.704（4）°, C32H40.50N6O8.25Cd, Mr = 753.60, V= 3511.2（2） A^3, Z = 4, Dc = 1.426 g/cm^3,μ（MoKα） = 0.679 mm^--1, F（000） = 1554, the final R = 0.0419 and wR = 0.0961 for 3627 independent reflections with Rint = 0.0440. The framework structures of complexes 1 and 2 are 3-D networks via the hydrogen bonds among 1-D chains. The notable characteristics of the two complexes are that the coordination polyhedron of Zn（Ⅱ） adopts a rare distorted five-coordinate square pyramidal geometry in 1, and the Cd（Ⅱ） complex exhibits an unusual distorted seven-coordinate pentagonal bipyramid in 2.

Synthesis and Crystal Structure of an Imino Nitroxide Complex [Cd(IM2py)_2Cl_2]

The title compound [Cd(IM2py)2Cl2], where IM2py = 2-(2?-pyridinyl)-4,4,5,5-tetra- methylimidazoline-1-oxyl, has been prepared and structurally characterized by X-ray diffraction. It crystallizes in monoclinic, space group C2/c with a = 18.436(6), b = 9.255(3), c = 15.831(5) ? b = 100.274(5)? C24H32CdCl2N6O2, Mr = 619.86, V = 2658.0(14) ?, Z = 4, Dc = 1.549 g/cm3, m(MoKa) = 1.056 mm-1, F(000) = 1264, the final R = 0.0324 and wR = 0.0659 for 2725 independent reflections with Rint = 0.0378. The title complex exists as discrete mononuclear molecules, adopting a distorted octahedral [cis(Cl)-trans(py)] configuration with the cadmium(II) ion being bonded to two bidentate radicals and two chlorine atoms. There exist p???p stacking interactions between the adjacent parallel pyridyl rings of the complex in the ac plane.

Exchange Interaction of a Novel Heterospin Polynuclear Complex Containing Transition Metals and Imino Nitroxide Radicals: {[(CuL)Ni(IM-2Py)_2](ClO_4)_2}_2·2H_2O

A novel heterospin complex {[(CuL)Ni(IM 2Py) 2](ClO 4) 2} 2·2H 2O (L=2,3 dioxo 5,6:14,15 dibenzo 1,4,8,12 tetraazacyclo pentadeca 7,12 diene, IM 2Py=2 (2′ pyridyl) 4,4,5,5 tetra^methyl 4,5 dihydro 1 H imidazoline 1 oxyl) has been synthesized and its crystal structure was determined by X ray diffraction analysis. In order to interpret the exchange interaction of this asymmetric heterospin system, a theoretical model has been established. Using this theoretical model the magnetic susceptibility data have been fitted and lead to coupling constant values equal to 1 4 cm -1 (Ni Rad) and -38 0 cm -1 (Ni Cu), respectively.

Synthesis and Crystal Structures of Two Metal-Radical Complexes

Two new M(II)-radical complexes [M(hfac)2(IM-o-QN)] (M = Ni(1), Zn(2);IM-o-QN = 4'-quinoxalinyl-substituted imino nitroxide;hfac = hexafluoroa-cetylacetonate) have been synthesized and characterized by X-ray diffraction analysis, element analyses, IR and UV-Visible spectroscopy. X-ray analysis reveal that the structures of both complexes are similar configuration and differently spatial symmetries. The complex 1 crystallizes in the triclinic Pī space group with the respective cell parameters: a = 9.1189(18) Å, b = 9.836(2) Å, c = 18.537(4) Å, α = 75.92(3)°, β= 81.95(3)°, γ = 69.32(3)°, V = 1506.1(5) Å3, Z = 2, whereas the complex 2 is in monoclinic C2/c space group with the respective cell parameters: a = 26.996(5) Å, b = 9.5223(19) Å, c = 23.961(5) Å, α = 90.00°, β= 91.07(3)°, γ= 90.00°, V = 6158(2) Å3, Z = 8. In two new M(II)-radical complexes, the central M(II)(Ni(1) and Zn(2)) ions are coordinated by four oxygen atoms from two hfac and two nitrogen atoms from imino nitroxide radicals to form a distorted octahedron. Additionally, the optical properties and thermal analysis of the two complexes are reported.