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1

Synthesis, characterization and Magnetic Studies of Oxamido-Bridged Copper(II)-Iron(III) Heterobinuclear Complexes

Li Y., Zhu C., Yan C., Dou J., Wang D.

Polish Journal of Chemistry

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2005

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Vol. 79 / nr 8

1265-1273

EN

Two new oxamido-bridged Cu(II)-Fe(III) heterobinuclear complexes of formulae [Cu(dmoxpn)Fe(bpy)2](ClO4)3 (1) and [Cu(dmoxae)Fe(bpy)2](ClO4)3 (2) have been synthesized, where bpy denotes 2,2_-bipyridine; while dmoxpn and dmoxae represent N,N_-bis[3-(dimethylamino)propyl]oxamido and N,N_-bis[2-(dimethylamino) ethyl]oxamido dianions, respectively. Based on elemental analyses, molar conductivity measurements, IR and electronic spectral studies, it is proposed that the two complexes have oxamido-bridged structures consisting of a copper(II) and an iron(III) ions, which have a square planar environment and a distorted octahedral environment, respectively. The two heterobinuclear complexes were further characterized by variable-temperature magnetic susceptibility (4.2~300 K) measurements and the observed data were simulated by the equation based on the spin Hamiltonian operator, H = JS S 1 2 2 , giving the exchange integral J = -18.2 cm-1 for (1) and J = -26.5 cm-1 for (2). The results revealed the occurrence of an intramolecular antiferromagnetic interaction between the adjacent iron(III) and copper(II) ions through the oxamido- -bridge within each molecule. The influence of the chelate ring arrangement around the copper( II) in the copper(II)-iron(III) heterobinuclear complexes on magnetic interactions between the metal ions of this kind of complexes is preliminarily discussed.

2

Synthesis and Magnetic Studies of Copper(II)-Lanthanide(III) Heterobinuclear Complexes Bridged by N,N'-Bis[3-(dimethylamino)propyl]oxamido

Li Y., Yan C., Wu Z., Zhu C.

Polish Journal of Chemistry

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2005

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Vol. 79 / nr 1

37-46

EN

Ten new copper(II)-lanthanide(III) heterobinuclear complexes bridged by N,N'-bis[3- (dimethylamino)propyl]oxamido dianions (dmoxpn) and end-capped with 2,2'-bipyridine (bpy), namely, Cu(dmoxpn)Ln(bpy)2(NO3)3 (Ln = La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb), have been synthesized and characterized by elemental analyses, molar conductivity measurements, and spectroscopic (IR, UV, ESR) studies. The Cu(dmoxpn)Gd(bpy)2(NO3)3 complex was further characterized by variable-temperature magnetic susceptibility (4.2~300 K) measurements and the magnetic data have been also used to deduce the indicated heterobinuclear structure. The results derived from least-squares fit of the experimental data have confirmed that the adjacent copper(II) and gadolinium(III) ions through the oxamido-bridge in the complex are ferromagnetically coupled with the exchange integral J(Cu-Gd) = +8.59 cm-1. A plausible mechanism for the ferromagnetic coupling between gadolinium(III) and copper(II) is discussed in terms of spin-polarization.

3

Synthesis and Magnetic Characterization of mi-Oxamido-bridged Cu(II)-M(III) (M=Fe and Cr) Heterobinuclear Complexes

Li Y., Yan C. -W., Guan H. -S.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 10

1235-1244

EN

Two new _-oxamido-bridged heterobinuclear complexes have been synthesized and identified as [Cu(dmoxae)Cr(Ph2phen)2](ClO4)3 (1) and [Cu(dmoxae)Fe(Ph2phen)2](ClO4)3 (2), where dmoxae denotes N,N_-bis[2-(dimethylamino)ethyl]oxamido dianion and Ph2phen represents 4,7-diphenyl-1,10-phenanthroline. Based on elemental analyses, IR, ESR and electronic spectra studies, and molar conductivity measurements, the complexes are proposed to have an extended oxamido-bridged structure consisting of planar copper(II) and octahedral chromium(III) or iron(III) ions. The two heterobinuclear complexes were further characterized by variable-temperature magnetic susceptibility (4.2~300 K) measurements and the magnetic data have been also used to deduce the indicated heterobinuclear structure. The results derived from least-squares fit of the experimental data have confirmed that the adjacent copper(II) and chromium(III) ions through the oxamido-bridge in complex (1) are ferromagnetically coupled with the exchange integral J(Cu-Cr) = +13.6 cm-1, while an intramolecular antiferromagnetic coupling is detected between the copper(II) and iron(III) ions through the oxamido-bridge in complex (2) with the exchange integral J(Cu-Fe) = -17.5 cm-1, on the basis of the spin Hamiltonian operator, _ _ _ H JS S Cu M = Ĺ 2 (M = Cr3+ and Fe3+). The influence of electronic-structural variation of the metal ions on the nature of spin-exchange interaction between the paramagnetic centers is also discussed.

4

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

Wrzeszcz G.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 7

845-854

EN

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.

5

Synthesis and Magnetism of Copper(II)-Lanthanoid(III) Heterobinuclear Complexes with N,N'

Li Y.-T., Yan C. -W., Wang G.-M.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 5

653-662

EN

Eleven novel ž-oxamido-bridged copper(II)-lanthanoid(III) heterobinuclear complexes described by the overall formula Cu(obp)Ln(Ph2-phen)2ClO4 (Ln = Y, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb), where obp denotes N,N_-oxamidobis(propionato) and Ph2-phen represents 4,7-diphenyl-1,10-phenanthroline (Ph2-phen), have been synthesized and characterized by elemental analyses, spectroscopic (IR, UV, ESR) studies, and molar conductivity measurements. The temperature dependence of the magnetic susceptibility of complex Cu(obp)Gd(Ph2-phen)2ClO4 has been measured over the range 4.2~300 K and the magnetic properties were studied in detail, demonstrating the presence of a very weak ferromagnetic interaction between the adjacent Gd(III) and Cu(II) ions through the oxamido-bridge. Based on the spin Hamiltonian operator, _ _ _ H = 2JS S 1 2 _ _ , the exchange integral (J) was evaluated as +2.98 cm-1. A plausible mechanism for the ferromagnetic coupling between Gd(III) and Cu(II) is discussed in terms of spin-polarization.

6

Synthesis and Magnetic Properties of Heterobinuclear Copper(II)-Manganese(II) Complexes with N, N'-Bis[2-(dimethylamino)ethyl]oxamide as Ligand

Li Y., Yan C. -W., Miao S. -H.

Polish Journal of Chemistry

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2001

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Vol. 75, nr 2

223-230

EN

Four new copper(II)-manganese(II) heterobinuclear complexes bridged by N,N - bis[2-(dimethylamino)ethyl)]oxamido dianion (dmoxae) and end-capped with 2,2 -bipyridine (bpy); 4,4 -dimethyl-2,2 -bipyridine (Me2-bpy); 5-chloro-1,10-phenanthroline (Cl-phen) or 5-bromo-1,10-phenanthroline (Br-phen), respectively, namely, [Cu(dmoxae)MnL2](ClO4)2 (L = bpy, Me2-bpy, Cl-phen, Br-phen), have been synthesized and characterized by elemental analyses, IR and electronic spectra studies and molar conductivity measurements. The electronic reflectance spectrum indicates the presence of exchange-coupling interaction between bridging copper(II) and manganese(II) ions. The cryomagnetic measurements (4.2-300 K) of [Cu(dmoxae)Mn(bpy)2](ClO4)2 complex demonstrated the operation of an antiferromagnetic interaction between the adjacent manganese(II) and copper(II) ions through the oxamido-bridge within the complex. On the basis of spin Hamiltonian, H = 2JS S 1 2 , the magnetic analysis was carried out for the complex and the spin-coupling constant (J) was evaluated as -36.9 cm-1. The influence of methyl substituents in amine groups of the bridging ligand on magnetic interactions between the metal ions of this kind of complexes is also discussed.

7

Synthesis, Characterization and Magnetism of Heterodinuclear Cu(II)-Fe(II) Complexes Bridged by N,N'-Oxamidobis(propionato)cuprate(II)

Li Y., Yan C., Zeng X.

Polish Journal of Chemistry

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2000

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Vol. 74, nr 8

1063-1070

8

Synthesis, Characterization and ferromagnetic Interaction in M-Oxamino Cu(II)-Cr(III) Heterodinuclear Complexes

Li Y., Yan C., Zeng X.

Polish Journal of Chemistry

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2000

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Vol. 74, nr 8

1055-1062

9

Synthesis and Magnetic Properties of heterobinuclear Copper(II)-Lanthanide(III) Complexes with N,N'-Oxamidobis(benzoato)cuprate(II) as Ligand

Li Y., Yan C., Zeng X.

Polish Journal of Chemistry

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2000

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Vol. 74, nr 5

631-638