Wyniki wyszukiwania - BazTech

1

Synthesis and magnetic Studies of mi-Iodanilato-Bridged Iron(III)-Iron(III) Binuclear Complexes

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

Polish Journal of Chemistry

|

2003

|

Vol. 77 / nr 8

935-942

EN

Four new _-iodanilato-bridged binuclear iron(III) complexes have been prepared and identified: [Fe2(IA)L4](ClO4)4, where IA represents the dianion of iodanilic acid and L denotes 2,2_-bipyridine (bpy); 1,10-phenanthroline (phen), 5-chloro-1,10-phenanthroline (Cl-phen) or 5-nitro-1,10-phenanthroline (NO2-phen). Based on elemental analyses, molar conductivity, magnetic moment of room-temperature measurements, IR and electronic spectra studies, these complexes are proposed to have extended IA-bridged structures consisting of two iron(III) ions, each in a distorted octahedral environment. The complexes [Fe2(IA)(bpy)4](ClO4)4 (1) and [Fe2(IA)(phen)4](ClO4)4 (2) were further characterized by variable temperature (4.2~300 K) magnetic susceptibility measurements and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator,_ _ _ H = 2JS S 1 2 Ĺ , giving the exchange parameter J = -6.9 cm-1 for (1) and J = -9.8 cm-1 for (2). These results are commensurate with antiferromagnetic spin-exchange interaction between the two iron(III) ions within each molecule. The influence of halogen substituents in the bridging ligand on magnetic interactions between the metal ions of this kind of complexes is also discussed.

2

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

|

2003

|

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.

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

|

2003

|

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 and Ferromagnetic Interaction in μ-Oxamido-Bridged Copper(II)-Oxovanadium(IV) Heterodinuclear Complexes

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

Polish Journal of Chemistry

|

2003

|

Vol. 77 / nr 8

943-959

EN

Three new copper(II)-oxovanadium(IV) heterodinuclear 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) or 5-chloro-1,10-phenanthroline (Cl-phen), have been synthesized and characterized; namely [Cu(obp)VO(phen)] (1), [Cu(obp)VO(NO2-phen)] (2) and [Cu(obp)VO(Cl-phen)] (3). The three 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 square-pyramidal oxovanadium(IV) ions. The heterodinuclear complexes (1) and (2) 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 heterodinuclear structure. The results derived from least-squares fit of the experimental data have confirmed that the operation of a ferromagnetic interaction between the adjacent oxovanadium(IV) and copper(II) ions through the oxamido-bridge within each molecule. Based on spin Hamiltonian, _ _ _ H = 2JS S 1 2 Ĺ , the exchange integral (J) was evaluated as J = +11.68 cm-1 for (1) and J = +10.27 cm-1 for (2). The influence of the symmetry of the magnetic orbitals on the nature of the magnetic interaction between the paramagnetic centers is also discussed.

5

Antiferromagnetically Coupled Binuclear Chromium(III) Complexes Through mi-Isophthalato-Bridge

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

Polish Journal of Chemistry

|

2003

|

Vol. 77 / nr 8

953-959

EN

Three new _-isophthalato-bridged binuclear chromium(III) complexes were synthesized and characterized, namely [Cr2(IPHTA)(Me2bpy)4](NO3)4 (1), [Cr2(IPHTA)(Me2phen)4](NO3)4 (2) and [Cr2(IPHTA)(Cl-phen)4](NO3)4 (3), where IPHTA represents the isophthalate dianions; Me2bpy, Me2phen and Cl-phen stand for 4,4_-dimethyl-2,2_-bipyridine; 2,9-dimethyl-1,10-phenanthroline and 5-chloro- 1,10-phenanthroline, respectively. The three complexes have not yet been isolated in crystalline form suitable for X-ray structure analysis, but based on elemental analyses, molar conductance and magnetic moments of room-temperature measurements, and spectroscopic studies, extended IPHTA-bridged structures consisting of two chromium( III) ions, each in an octahedral environment are proposed for these complexes. The complexes [Cr2(IPHTA)(Me2bpy)4](NO3)4 (1) and [Cr2(IPHTA)(Me2phen)4](NO3)4 (2) were further characterized by variable temperature magnetic susceptibility (4~300 K) measurements and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, _ _ _ H JS S = Ĺ 2 1 2, giving the exchange integrals J = -1.27 cm-1 for (1) and J = -2.19 cm-1 for (2). This result indicates the presence of weak antiferromagnetic spin-exchange interaction between the metal ions within each molecule.