Related Experiment Video
Updated: Jan 22, 2026
Crystallizing Membrane Proteins for Structure Determination using Lipidic Mesophases
Published on: November 21, 2010
Solvent-assisted structural conversion involving bimetallic complexes based on the tris(oxalato)ferrate(iii) unit
Tadeusz M Muzioł1, Natalia Tereba1, Robert Podgajny2
1Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Toruń, Poland. tmuziol@umk.pl.
Abstract:
Three new complexes forming a dynamic system and given by the following formulae: [Cu2(bpy)4Fe(ox)3]NO3·H2O 1, [Fe(bpy)3]2[Fe(ox)3]NO3·10H2O 2 and [Cu(bpy)3]2[Fe(ox)3]NO3·10H2O 3 (bpy - 2,2'-bipyridine, ox - oxalate), were synthesized from a methanol-water mixture or water, and characterized structurally, spectroscopically and magnetically. Compound 1 contains trinuclear [(bpy)2Cu(μ-ox)Fe(ox)(μ-ox)Cu(bpy)2]+ cations, while 2 and 3 can be classified as isomorphous ionic compounds, with alternately arranged hydrophobic and hydrophilic layers of mononuclear complex ions. The green crystals of 1 are perfectly stable in air, whereas in selected solvents they undergo irreversible solvent-assisted recrystallization towards red crystals of 2, which is also accompanied by the appearance of mononuclear blue copper complexes with oxalate, 2,2'-bipyridine and aqua ligands, already described in the literature. The above crystallization/recrystallization processes indicate variable solution contents. The whole effect is accelerated by both the increased temperature and day light irradiation, however, different products from the pool prevail under various conditions. The observed transformation can be understood in terms of thermodynamic and kinetic control, involving the known photo-activity of [Fe(ox)3]3- moieties and the effect of quadruple aryl embrace (QAE) on the stability of the crystal network. Considering the presence of FeIII-ox-CuII connectivity in 1 we performed detailed magnetic studies and theoretical calculations for this compound. Due to the strong asymmetry of Cu-O bonds the antiferromagnetic coupling is rather weak, with JCu-Fe being ca. -3.4 cm-1 (using Hamiltonian of the type H = -JCu-Fe(SCu1SFe + SFeSCu2) -JCu-Cu(SCu1SCu2)). We found that these values are very close to those predicted by B3LYP/6-311G* calculations.
More Related Videos
Related Concept Videos
02:58Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
03:02Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
01:36Conversion of Units
The first step in the unit conversion is to list the given units and the units required...
02:42Ionic Crystal Structures
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
01:26Per-Unit Sequence Models
Zero-sequence currents, which are identical in magnitude and phase, generate a neutral current, resulting in voltage drops across the neutral impedance and the low-voltage winding. If the...
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...