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3 Polish Journal of Chemistry

3 2003

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Synthesis and Characterization of New Thiocyanato Bridged Heterobimetallic Complexes with the General formula: [Cu(diamine)2]3[Cr(NCS)6]2.nH2O

100%

Wrzeszcz G.

tom Vol. 77 / nr 7

845-854

Four new thiocyanato bridged heteropolynuclear complexes with general formula [Cu(diamine)2]3[Cr(NCS)6]2_nH2O, where diamine = N-ethylethylenediamine (N-Et-en), N-isopropylethylenediamine (N-Pri-en), N-methyl-1,3-propanediamine (N-Me-tn), 1,3-diaminopentane (C-Et-tn), were prepared by treatment of corresponding cationic [Cu(diamine)2]2+ complex with [Cr(NCS)6]3-in aqueous solutions. Solid products were formulated as [Cu(N-Et-en)2]3[Cr(NCS)6]2, [Cu(N-Pri-en)2]3[Cr(NCS)6]2_2H2O, [Cu(N-Me-tn)2]3[Cr(NCS)6]2_H2O and [Cu(C-Et-tn)2]3[Cr(NCS)6]2_H2O and characterized by spectroscopic methods, magnetic measurements and thermal analysis. The formation of end-to-end thiocyanato bridges between tetragonal Cu(II) and octahedral Cr(III) is evident from IR and electronic spectra. The EPR spectra measured at room temperature on solid samples show broad, symmetric signal at g = 2.01-2.03. Variable-temperature magnetic susceptibility measurements reveal the presence of weak antiferromagnetic interactions in [Cu(N-Pri-en)2]3[Cr(NCS)6]2_2H2O and [Cu(C-Et-tn)2]3[Cr(NCS)6]2_H2O. Thermal decomposition after dehydration is multistage and yields CuO and CuCrO2 as final products.

Spectroscopic, Magnetic and Thermal Properties of New Thiocyanato Bridged Complexes of the Type [M(diamine)2]3[Cr(NCS)6]2.nH2O4, where M=Cu(II), Ni(II)

84%

Wrzeszcz G. , Dobrzańska L.

2003

tom Vol. 77 / nr 10

1245-1254

Heteropolynuclear complexes of the type [M(diamine)2]3[Cr(NCS)6]2_nH2O, where diamine = N-methylethylenediamine (N-Me-en), 1,2-diaminopropane (pn); M = Ni(II), Cu(II) have been prepared by reacting [Cr(NCS)6]3- with the corresponding cationic [M(diamine)2]2+ complex in an aqueous solution. They have been characterized by elemental analysis, IR, UV-VIS, EPR, variable temperature magnetic susceptibility and thermal analysis. Spectroscopic studies reveal thiocyanato bridges between M(II)-Cr(III) centres. The parameters determined from temperature dependence on magnetic susceptibility (80-300 K) indicate moderate antiferromagnetic interactions for Ni(II)-Cr(III) and negligibly small or very weak ones for Cu(II)-Cr(III) systems. Magnetic studies suggest also presence of diamagnetic Ni(II) ions in the structure of Ni(II)-pn-Cr(III) complex. Thermal analysis shows higher thermal stability of Ni(II)-Cr(III) than Cu(II)-Cr(III) compounds. The process of thermal decomposition after dehydration is multistage and yields NiO + NiCr2O4and CuO + CuCrO2 as final products, respectively.

Synthesis and Characterization of New Thiocyanato Bridged Complexes with the General Formula [MLn}3[Cr(NCS)6]2.mH2O, where M=Cu(II), Ni(II), Co(II); L=Various Substituted Imidazoles

67%

Wrzeszcz G. , Dobrzańska L. , Grodzicki A. , Rozpłoch F.

tom Vol. 77 / nr 2

147-156

New thiocyanato bridged complexes of the type [CuL4]3[Cr(NCS)6]2_mH2O [L = 1-methylimidazole (1-Meim), 2-methylimidazole (2-Meim), 1,2-dimethylimidazole (1,2- Me2im)] and [M(1-Meim)6]n[{M(1-Meim)4Cr(NCS)6}2n]_mH2O (M = Ni(II), Co(II) were prepared by the reaction of [Cr(NCS)6]3- with the appropriate [MLn]2+ complex in an aqueous solution and characterized by elemental and thermal analysis, IR, UV-VIS, EPR and temperature variable magnetic susceptibility. The presence of NCS bridges between M(II)-Cr(III) centres is evident from IR spectra. The electronic spectra correlate with proposal of different composition of Cu3Cr2 and M3Cr2(M = Ni, Co) systems. The parameters determined from temperature dependence on magnetic susceptibility (80-300 K) indicate weak or negligible antiferromagnetic interaction for obtained Cu(II)-Cr(III), Ni(II)-Cr(III) and Co(II)-Cr(III) systems. Thermal decomposition after dehydration is multistage and yields CuO + CuCrO2 and MIIO+MIICr2O4 as final products, respectively.