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Synthesis and Magnetic Analysis of mi Oxamido-Bridged Cu(II)-Fe(II) Heterodinuclear Complexes

Li Y., Zhang G., Yan C., Dou J., Wang D.

Polish Journal of Chemistry

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2005

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Vol. 79 / nr 9

1405-1413

EN

The strategy of "complex as ligand" allowed us to synthesize two new mi-oxamido- bridged heterodinuclear complexes identified as [Cu(bmap)Fe(bpy)2]SO4 (1) and [Cu(bmap)Fe(phen)2]SO4 (2), where bmap represents the N,N'-bis(2-methyl-2-aminopropyl) oxamido dianion; bpy and phen stand for 2,2'-bipyridine and 1,10-phenanthroline, respectively. These complexes are the first examples of copper(II)-iron(II) species bridged by bmap groups. Based on elemental analyses, IR and electronic spectra studies, magnetic moments at room temperature and molar conductivity measurements, these complexes are proposed to have an extended oxamido-bridged structure consisting of planar copper(II) and octahedral iron(II) ions. The two heterodinuclear complexes have been further characterized by variable temperature magnetic susceptibility (4.2-300 K) and the observed data were least-squares fitted to the susceptibility equation derived from the spin Hamiltonian including single-ion zero-field interaction for the iron(II) ion,H=-2JS1 . S2-DS2 Z1 , giving the exchange integrals J = -18.9 cm-1 for (1) and J = -20.1 cm-1 for(2). These results indicated that the spin coupling between the adjacent copper(II) and iron(II) ions through the oxamido-bridge in both complexes (1) and (2) is antiferromagnetic. The influence of methyl substituents in the bridging ligand on magnetic interactions between the metal ions of this kind of complexes is also discussed

2

Synthesis and Magnetic Studies of Copper(II)-Iron(II) Heterodinuclear Complexes with N,N'-Bis[2-dimethylamino)ethyloxamido Dianion as Ligand

Li Y., Yan C., Lou J., Zhu C.

Polish Journal of Chemistry

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2004

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Vol. 78 / nr 5

635-644

EN

Three new copper(II)-iron(II) heterodinuclear complexes bridged by the dianions of N,N_-bis[2-(dimethylamino)ethyl]oxamido (dmoxae) and end-capped with 2,2_-bipyridine (bpy); 1,10-phenanthroline (phen) or 5-nitro-1,10-phenanthroline (NO2phen); namely [Cu(dmoxae)Fe(bpy)2]SO4 (1), [Cu(dmoxae)Fe(phen)2]SO4 (2) and [Cu(dmoxae)Fe(NO2phen)2]SO4 (3), have been synthesized and characterized. The three dinuclear complexes have not yet been isolated in crystalline form suitable for X-ray structure analysis, but based on elemental analyses, IR and electronic spectra studies, magnetic moments at room-temperature and molar conductivity measurements, these complexes are proposed to have an extended oxamido-bridged structure consisting of planar copper(II) and octahedral iron(II) ions. The [Cu(dmoxae)Fe(bpy)2]SO4 (1) and [Cu(dmoxae)Fe(phen)2]SO4 (2) complexes have been further characterized by variable temperature magnetic susceptibility (4.2~300 K) and the observed data were least-squares fitted to the susceptibility equation derived from the spin Hamiltonian including single-ion zero-field interaction for the iron(II) ion, _H =-2J_S1_ _ S2 - D_SZ1 2 , giving the exchange integrals J = -20.9 cm-_ for (1) and J = -22.7 cm-1for (2). These results indicated that the spin coupling between the adjacent copper(II) and iron(II) ions through the oxamido-bridge in both complexes (1) and (2) is antiferromagnetic. The influence of methyl substituents in the amine groups of the bridging ligand and the relative stability of the chelate ring arrangement around the copper(II) on magnetic interactions between the metal ions of this kind of complexes is also discussed.

3

Synthesis and Magnetic Analysis of mi-Oxamido-Bridged Copper(II)-Iron(II) Heterodinuclear 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 2

137-145

EN

Five new copper(II)-iron(II) heterodinuclear complexes bridged by the dianion of N,N_-bis[3-(dimethylamino)propyl]oxamido (dmoxpn) and end-capped with 2,2_-bipyridine (bpy); 1,10-phenanthroline (phen); 5-nitro-1,10-phenanthroline (NO2-phen); 5-chloro-1,10-phenanthroline (Cl-phen) or 5-bromo-1,10-phenanthroline (Br-phen); namely [Cu(dmoxpn)FeL2](ClO4)2 (L = bpy, phen, NO2-phen, Cl-phen, Br-phen), have been synthesized and characterized. Based on elemental analyses, magnetic moments (at room temperature), molar conductivity measurements, and spectroscopic studies, extended oxamido-bridged structures consisting of a copper(II) ion and an iron(II) ion, which have a square-planar environment and an octahedral environment, respectively, are proposed for these complexes. The [Cu(dmoxpn)Fe(bpy)2](ClO4)2 (1) and [Cu(dmoxpn)Fe(phen)2](ClO4)2 (2) complexes have been further characterized by variable temperature magnetic susceptibility (4.2~300 K) and the observed data were least-squares fitted to the susceptibility equation derived from the spin Hamiltonian including single-ion zero-field interaction for the iron(II) ion,_ _ _ _ H = 2JS S DS 1 2 Z1 2 Ĺ , giving the exchange integrals J = -15.9 cm-1 for (1) and J = -17.5 cm-1 for (2). These results indicated that the spin coupling between the adjacent copper(II) and iron(II) ions through oxamido-bridge in both complexes (1) and (2) is antiferromagnetic. The influence of methyl (-CH3) substituents in the bridging ligand on magnetic interactions between the metal ions of this kind of complexes is also discussed.

4

Synthesis, Characterizationand Ferromagnetic Spin-Coupling Between Chromium(III) and Copper(II) Ions in Oxamido Bridget Cu(II)-Cr(III) Dinuclear Complexes

Li Y., Yan C. W., Hu C. X.

Polish Journal of Chemistry

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2001

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Vol. 75, nr 3

329-336

EN

Four new heterodinuclear copper(II)-chromium(III) complexes bridged by dianions of N,N -oxamidobis(propionato)cuprate [Cu(obp)] and end-capped with 1,10-phenanthroline (phen), 5-nitro-1,10-phenanthroline (NO2-phen), 5-chloro-1,10-phenanthroline (Cl-phen) or 5-bromo-1,10-phenanthroline (Br-phen); namely [Cu(obp)Cr(L)2]NO3 (L = phen, NO2-phen, Cl-phen, Br-phen), have been synthesized and characterized by elemental analyses, IR and electronic spectra studies, magnetic moments at room-temperature and molar conductivity measurements. It is proposed that these complexes have extended oxamido-bridged structures consisting of a copper(II) ion and a chromium(III) ion, which have a square-planar environment and an octahedral environment, respectively. The magnetic susceptibility of [Cu(obp)Cr(phen)2]NO3 complex was measured between 4.2 300 K and the magnetic analysis was studied in detail, demonstrating the operation of a ferromagnetic interaction between the adjacent chromium(III) and copper( II) ions through the oxamido-bridge within the complex. Based on spin Hamiltonian, H= - 2JS S 1 . S 2, the exchange integral (J) was evaluated as 12.8 cm -1.

5

Synthesis and Magnetism of mi-Oxamido-bridged Cu2 II Ln III -type Heterotrinuclear Complexes (Ln=Ce, Nd, Sm, Eu, Gd, Tb, Dy, Er)

Li Y., Yan C. W.

Polish Journal of Chemistry

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2001

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Vol. 75, nr 3

355-362

EN

Eight new Cu2 IILnIII-type (Ln = Ce, Nd, Sm, Eu, Gd, Tb, Dy, Er) heterotrinuclear complexes bridged by N,N_-bis(2-aminopropyl)oxamidocopper(II) [Cu(oxdn)], namely Cu2(oxdn)2Ln(NO3)3, have been synthesized and characterized by elemental analyses, molar conductivity measurements and spectroscopic (IR, UV, ESR) studies. Magnetic susceptibility measurements (4.2~300 K) and studies of Cu2(oxdn)2Gd(NO3)3 complex have revealed that the central gadolinium(III) and terminal copper(II) ions are ferromagnetically coupled with the exchange integral J(Cu-Gd) = +2.98 cm-1, while an antiferromagnetic coupling is detected between the terminal copper(II) metal ions with the exchange integral J(Cu Cu) ' _ = _0.75 cm-1, on the basis of the spin Hamiltonian operator [H 2J(S S S S ) 2J'(S S Cu1 Gd Cu2 Gd Cu1 Cu2