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|Title: ||Synthesis, characterization and coordination chemistry of some selenium-containing macrocyclic Schiff bases|
|Authors: ||PANDA, A|
|Issue Date: ||2005|
|Publisher: ||WILEY-V C H VERLAG GMBH|
|Citation: ||EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, (6), 1114-1126|
|Abstract: ||The condensation of bis(o-formylphenyl) selenide with 1,2-diaminoethane or 1,3-diaminopropane yielded the new macrocyclic ligands 1 and 2 in very good yields. Crystals of 1 are monoclinic, space group P2(1)/c with a = 10.0648(10) angstrom, b = 37.390(4) angstrom, c = 8.0073(11) angstrom, Z = 4 and those of 2 are triclinic, space group P (1) over bar with a 7.200(3), b = 9.137(3), C = 12.780(6) angstrom, Z = 1. The coordination chemistry of 1 and 2 has been studied with the "soft" metal ion Pd-II and "hard" metal ions Ni-II and Co-II. Reaction of [PdCl2(COD)] with 1 mol-equiv. of 1 or 2 in refluxing methanol and addition of NH4PF6 afforded the PdII complexes 5 and 6, respectively. Compound 5 is an unexpected partially hydrolyzed complex. It crystallizes in the tetragonal space group P4(1)2(1)2 with a = 10.7737(10) angstrom, b = 10.7737(10) angstrom, c = 28.190(5) angstrom, Z = 4. The structure shows the Pd-II ion coordinated to a square-planar arrangement of two selenium and two nitrogen atoms. Reaction of NiCl(2)(.)6H(2)O with I or 2 and NH4PF6 yielded complexes 7 and 8, respectively. The assignment of octahedral geometries to [Ni(L)](PF6)(2)] (7: L = 1; 8: L = 2) follows from their paramagnetism [mu(eff) = 3.23 (7), 1.81 (8) B.M.] and their UV/Vis spectra. This was also confirmed by single-crystal Xray studies. The crystal structures of 7 and 8 showed a distorted octahedral nickel center coordinated by two selenium and four nitrogen atoms. 7: Monoclinic, space group P21/c; a 9.979(2) angstrom, b = 18.901(4) angstrom, c = 19.333(4) angstrom; Z = 4. 8:Orthorhombic, space group Pna2(1); a = 20.277(5), b = 20.865(5), c = 9.416(2) angstrom; Z = 4. The cyclic voltammograms of 7 and 8 in MeCN solution show well-behaved quasi-reversible Ni-III/Ni-II couples. The analogous Co-II complex, [Co(1)](PF6)(2)] (9) also shows a quasi-reversible Co-III/Co-II couple. (c) Wiley-VCH Verlag GmbH T Co. KGaA, 69451 Weinheim, Germany, 2005.|
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