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1

Synthesis, Characterization and magnetic Properties of mi-2-Nitroterephthalato Binuclear Iron(II) Complexes

Li Y., Yan C. -W.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 6

765-771

EN

Four new binuclear iron(II) complexes bridged by 2-nitroterephthalato groups (NTPHA) and ended with 4,4_-dimethyl-2,2_-bipyridine (Me2-bpy), 2,9-dimethyl-1,10-phenanthroline (Me2-phen), 5-chloro-1,10-phenanthroline (Cl-phen) or 5-bromo-1,10-phenanthroline (Br-phen), namely [Fe2(NTPHA)L4](ClO4)2 (L=Me2-bpy,Me2-phen, Cl-phen, Br-phen), have been synthesized and characterized. Based on elemental analyses, magnetic moments (at room temperature), molar conductance measurements, and spectroscopic studies, extended NTPHA-bridged structures consisting of two iron(II) ions, each in a distorted octahedral environment are proposed for these complexes. The variable temperature magnetic susceptibilities of complexes [Fe2(NTPHA)(Me2-bpy)4](ClO4)2 (1) and [Fe2(NTPHA)(Me2-phen)4](ClO4)2 (2) were measured over the range 4.2~300 K and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, _ _ _ H JS S _ _ _ 2 1 2, giving the exchange integrals J = -1.02 cm-1 for (1) and J = -1.96 cm-1 for (2). These results indicate the presence of a very weakly antiferromagnetic spin-exchange interaction between the iron(II) ions within each molecule. The influence of nitro substituent in the bridging ligand on magnetic interaction between the metal ions of this kind of complexes is also discussed.

2

Synthesis and Magnetic Studies of Binuclear Iron(II) Complexes Bridged by Tetracarboxylato Groups

Li Y., Yan C. -W.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 12

1681-1687

EN

Four novel binuclear iron(II) complexes, namely [Fe2(PMTA)L4], where L denotes 4,4_-dimethyl-2,2_-bipyridine (Me2-bpy); 1,10-phenanthroline (phen); 5-chloro-1,10- phenanthroline (Cl-phen) or 5-bromo-1,10-phenanthroline (Br-phen), respectively, and PMTA stands for the tetraanion of pyromellitic acid, have been synthesized and characterized. Based on elemental analyses, magnetic moments at room-temperature and molar conductivity measurements, and spectroscopic (electronic and IR spectra) studies, extended PMTA-bridged structures consisting of two iron(II) ions, each in a distorted octahedral environment, are proposed for these complexes. The variable temperature magnetic susceptibilities (4_300 K) of the complexes [Fe2(PMTA)(Me2-bpy)4] (1) and [Fe2(PMTA)(phen)4] (2) were measured and the magnetic analysis was carried out by least-square method to the observed data with the susceptibility equation derived from the spin Hamiltonian operator, _ _ _ H 2JS S 1 2 _ _ _ , giving the exchange integrals J = _1.09 cm_1 for (1) and J = ___18 cm_1 for (2). The results indicate that there is a very weak antiferromagnetic spin-exchange interaction between the Fe(II) ions within each molecule.

3

Synthesis and Magnetic Properties of -Chloranilato-Bridged Binuclear Iron(II) Complexes

Li Y., Yan C., Zeng X.

Polish Journal of Chemistry

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1999

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Vol. 73, nr 10

1673-1679

EN

Based on elemental analyses, molar conductivity, magnetic moment of room-temperature measurements and spectroscopic studies, it is proposed that these complexes have CA-bridged structures and consist of two iron(II) ions, each in a distorted octahedral environment. This result indicates that there is a weak antiferromagnetic spin-exchange interaction between the two Fe(II) ions within each molecule.

4

Synthesis and antiferromagnetic interaction in tetrabromoterephthalato-bridged binuclear iron(II) complexes

Li Y., Yan C.

Polish Journal of Chemistry

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1999

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vol. 73 nr 3

417-424

EN

Five new binuclear iron(II) complexes have been synthesized and characterized , namely: [Fe2(BTPHA)L4]ClO4)2, where L stands for 4,4'-dimethyl-2,2'-bipyridyne (Me2-bpy); 2,9-dimethyl-1,10-phenanthroline (Me2-phen); 5-bromo-1,10-phenanthroline (Br-phen); 5-chloro-1,10-phenanthroline (Cl-phen) and 5-methyl-1,10-phenanthroline (ME-phen), respectively, and BTPHA represents the tetrabromoterephthalate dianion. Based on the elemental analyses, molar conductance measurements, and spectroscopic studies, extended BTPHA-bridged structures consisting of two iron (II) ions, each in an octahedral environment are proposed for these complexes. The variable temperature magnetic susceptibilities (4-300 K) for [Fe2(BTPHA)(Me2-bpy)4](ClO4)2 (1) and [Fe2(BTPHA)(Me2-phen)4](ClO4)2 (2) complexes were measured and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, H=-2J S1×S2, giving the exchanche integrals J= -1.09 cm -1 for (1) and J= -2.13 cm-1 for (2). These results indicate the presence of a weak antiferromagnetic spin-exchange interaction between the metal ions within each molecule. The influence of the bromo substituents in the bridge ligand on the magnetic interactions between the metal ions in this kind of complexes is also discussed.

5

Synthesis and magnetism of binuclear iron (II) complexes bridged by terephthalato dianions

Li Y.T., Yan C.W., Liao D.Z.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 5

832-838

EN

Four new terephthalato-bridges iron(II) binuclear complexes of the formula [Fe2(TPHA)L4](ClO4)2, where L stands for 4,4'-dimethyl-2,2'-bipyridine (Me2bpy); 2,9-dimethyl-1,10-phenanthroline (Me2phen); 5-bromo-1,10-phenanthroline (Br-phen); 5-chloro-1, 10-phenanthroline (Cl-phen), respectively, and TPHA represents the terephthalate dianion, have been synthesized and characterized. Based on the elemental analyses, molar conductance and magnetic moments of room-temperature measurements, and spectroscopic studies, extended TPHA-bridged structures consisting of two iron(II) ions, each in an octahedral environment are proposed for these complexes. The [Fe2(TPHA)(Me2bpy)4](ClO4)2 (1) and [Fe2(TPHA)(Me2phen)4](ClO4)2 (2) complexes were characterized by variable temperature magnetic susceptibility (4-300K) measurements and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, H=-2JS-1xS-2, giving the exchange integrals J=-2.15 cm -1 for (1) and J=-3.28 cm-1 for (2). This result indicates the presence of a weak antiferromagnetic spin-exchange interaction between the metal ions within each molecule.