Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 3

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  mi-oxalato-bridge
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
EN
Two new mi-oxalato-bridged binuclear chromium(III) complexes, [Cr2(ox)(salen)(bpy)2]- (NO3)2 (1) and [Cr2 (ox)(salen)(phen)2](NO3)2 (2) [where salen = N,N'-ethylenebis- (salicylideneiminate), ox = oxalato, bpy = 2,2'-bipyridine and phen = 1,10-phenanthroline], have been synthesized by the strategy of 'complex as ligand', and characterized by elemental analyses, molar conductance and magnetic moments of room-temperature measurements, and spectroscopic studies. It is proposed that the two complexes have extended ox-bridged structures consisting of two chromium(III) ions, each in an octahedral environment. The two complexeswere further characterized by variable temperature magnetic susceptibility (4.2~300 K) measurements and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, H= - 2JS S 1 2 giving the exchange integrals J = -2.78 cm-1 for (1) and J = -3.85 cm-1 for (2). This result indicates the presence of weak antiferromagnetic interaction between the metal ions within each molecule.
EN
The strategy of "complex as ligand" allowed us to synthesize three new _-oxalatobridged heterotetranuclear complexes identified as [Cu3Fe(ox)3(Me2bpy)3](ClO4)3 (1), [Cu3Fe(ox)3(Me2phen)3](ClO4)3 (2) and [Cu3Fe(ox)3(phen)3](ClO4)3 (3), where ox represents the oxalato dianions; Me2bpy, Me2phen and phen stand for 4,4_-dimethyl- 2,2_-bipyridine, 2,9-dimethyl-1,10-phenanthroline or 1,10-phenanthroline, respectively. These complexes are the first examples of [Cu3 IIFeIII] species bridged by oxalato groups. Based on elemental analyses, molar conductivity and magnetic moment (at room-temperature) measurements, IR, ESR and electronic spectral studies, these complexes are proposed to have oxalato-bridged structure consisting of three copper(II) ions and an iron(III) ion, in which the iron(III) ion has an octahedral environment, and the three copper(II) ions have a square-planar environment. The complexes (1) and (2) 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= 2J(S S S S S S Cu1 Fe Cu2 Fe Cu3 Fe Ĺ + Ĺ + Ĺ ), giving the exchange integrals J = -9.15 cm-1 for (1) and J = -8.79 cm-1 for (2). The results indicate the presence of an antiferromagnetic spin-exchange interaction between the copper(II) and iron(III) ions through the oxalato-bridge in both complexes (1) and (2).
EN
Three new binuclear chromium(III) complexes bridged by tris(oxalato)chromate(III), [Cr(ox)3]3- and end-capped with 2,2_-bipyridine (bpy); 4,4_-dimethyl-2,2_-bipyridine (Me2bpy) or 5-methyl-1,10-phenanthroline (Mephen), have been synthesized and characterized, namely [Cr2(ox)3(bpy)2] (1), [Cr2(ox)3(Me2bpy)2] (2) and [Cr2(ox)3(Mephen)2] (3). At present, 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 ox-bridged structures consisting of two chromium(III) ions, each in an octahedral environment are proposed for these complexes. The complexes [Cr2(ox)3(bpy)2] (1) and [Cr2(ox)3(Me2bpy)2] (2) were further characterized by variable temperature magnetic susceptibility (4.2~300 K) measurements and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, H_ = 2JS_ ĹS_ 1 2, giving the exchange integrals J = -9.73 cm-1 for (1) and J = -5.29 cm-1 for (2). This result indicates the presence of weak antiferromagnetic spin-exchange interaction between the metal ions within each molecule. The influence of the methyl substituents in the terminal ligand on magnetic interactions between the metals is also discussed.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.