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Research has been conducted on the heterometallic copper(II)-lanthanide(III) compounds. The hydrothermal reaction between Ln (sub)2 O (sub)3, where Ln= Dy and Ho, and oxydiacetic acid has been carried out in producing isostructural polymers crystallizing in the hexagonal crystal system and the details are reported.

Results describe the synthesis and the structural and magnetic characterization of two new copper complexes with 1-phenyl-3,5-dimethylpyrazole along with bromine and chlorine. Data reveal that bromine and chlorine ions change compound structures and bond geometry.

The ion pair charge-transfer complexes (C14H12N2)(Cu(opba))*3H2O and Na2(C12H12N2)(Cu(opba))2*4H2O were synthesized and their crystal structure and physical properties investigated. The crystal structures are comprised of alternated anion complex and diquaternary cation layers pi-pi interacting through the corresponding aromatic rings. Electron spin resonance data confirmed the dimeric nature of the compounds and revealed the existence of small zero-field splitting in a triplet state. The /J/ values were accurately calculated due to the observation of the two forbidden singlet-triplet transitions, which undergo marked shifts with temperature.

Electron paramagnetic resonance (EPR) and magnetic susceptibility measurements were utilized to analyze the structure of a ternary copper complex with L-aspartic acid and phenanthroline. The crystal lattice of the compound was composed of two different copper ions lying in two types of copper chains running parallel to the crystal axis. Hydrogen bonds and hydrophobic interactions held the chains together.

Research has been conducted on the mononuclear-ligand complex [Gd(CF (sub)3 CO (sub)2) (sub)3 (phen) (sub)2 (H (sub)2 O)]. The preparation, the single-crystal structure and the magnetic behavior of this complex have been examined and the results are discussed.

An extremely weak exchange interaction supported by a long chemical path of 18.34 Angstrom bridging copper ions in the copper complex of the peptide L-alanyl-L-phenyalanine is evaluated. This path includes a sequence of strong covalent bonds plus two moderate and one weak hydrogen bond and the results are compared with the exchange interaction transmitted by similar paths containing sigma bonds and H bonds in biomolecules and other model compounds.

Research has been conducted on cobalt(II) compounds containing L-threonine. The authors have investigated the structure and magnetic properties of this compound, and report that it crystallizes in the orthorhombic chiral space group.

Examines the hydrothermal reaction and oxydiacetic acid in maloe ratio. Formation of isostructural series of polymers; Susceptibility of temperature-dependent magnetic structures; Discussion on the exchange interactions between magnetic ions.

Structural, magnetic, and powder and single-crystal electron paramagnetic resonance (EPR) studies were performed on [{Cu(bipy)(en)}{Cu(bipy)(H2O)}{VO3}4]n (bipy = 2,2′-bipyridine, en = ethylenediamine), which is a new copper-vanadium hybrid organic-inorganic compound containing CuII and VV centers. The oxovanadium units provide an anionic scaffolding to the structure, where two types of CuII coordination modes, octahedral (Cu1) and square pyramidal (Cu2), contribute to the magnetic properties. The crystal structure contains layers including Cu1 and Cu2 ions, separated by stacked arrangements of 2,2′-bipyridine molecules. Each type of CuII ion in these layers forms parallel spin chains described by exchange coupling parameters J1 and J2 for Cu1 and Cu2, respectively (exchange couplings defined as ℋex(i,j)= -JijSiSj), which, for necessity, are assumed to be equal to J. These chains are coupled by much weaker Cu1-Cu2 exchange interactions J3 connecting neighbor Cu1 and Cu2 ions within a layer, through paths acting as rungs of a ladder chain structure. The average coupling J, which is antiferromagnetic (J < 0), according to the susceptibility data, is estimated with similar results with a mean field approximation (J = -1.4 cm-1), and with a uniform chain model (J = -1.7 cm-1). The EPR spectra of powdered samples and oriented single crystals are shown to be independent of J1 and J2, but are dependent on the weak coupling J3, and the data allow a lower limit to be established: ∣J3∣ > 0.04 cm-1. The spectra are also strongly sensitive to extremely weak coupling interactions with average magnitude J4 between copper atoms in neighboring layers, separated by 10 Å, using the stacked 2,2′-bipyridine molecules, which produce a 2D-to-3D quantum phase transition. This is observed in single-crystal samples when the energy levels are changed with the orientation of the magnetic field. From the characteristics of these transitions, we estimate a value of ∣J4∣ = 0.0034 ± 0.0004 cm-1 between CuII ions in neighboring layers. This work emphasizes the important possibilities of EPR to evaluate extremely small exchange couplings between metal ions in a solid material, even in the presence of other much larger couplings. [ABSTRACT FROM AUTHOR]

A CuII⋯CuII pyrophosphate-bridged compound of formula {[Na3Cu(P2O7)(NO3)]·3H2O}n (1) has been characterized. X-ray diffraction measurements show that it crystallizes in the monoclinic space group P21/m, with unit cell dimensions a = 7.2492(5) Å, b = 8.2446(6) Å, c = 9.9050(7) Å, β = 107.123(1)°, and Z = 2. The structure consists of chains of CuII cations at inversion symmetry sites bound to four equatorial oxygen atoms provided by two pyrophosphate anions halved by a symmetry plane and two axial oxygen atoms of nitrate anions. The molar magnetic susceptibility ?0 of a powdered sample was measured in the temperature range 2 K < T < 273 K, and an isothermal magnetization curve, M(B0,T), was obtained at T = 30 K, with the magnetic field B0 between 0 and 5 T. Fitting a spin-chain model to the susceptibility data, we evaluate an antiferromagnetic exchange coupling 2J = -24.3(1) cm-1 (defined as Hex = -2JSiSj) between CuII neighbors. For any orientation of B0, single-crystal electron paramagnetic resonance (EPR) spectra obtained at 9.8 and 33.9 GHz at 300 K display a single signal having a g matrix with orthorhombic symmetry, arising from the merger produced by the exchange interaction of the resonances corresponding to the two rotated CuII sites. The g matrices of the individual molecules calculated assuming axial symmetry yielded principal values g = 2.367(1) and g = 2.074(1) at both frequencies, indicating a dx²-y² ground-state orbital for the CuII ions. The angular variation of the EPR line width suggests exchange narrowing in a system with one-dimensional spin dynamics, as expected from the structure and susceptibility data. The results, discussed in terms of the crystal and electronic structures and of the spin dynamics of the compound, are compared with those obtained in other materials. [ABSTRACT FROM AUTHOR]