A. V. Rotov

anti-syn and anti-anti coordination of the bridging CO32− group in [Cu2(Phen)4(μ-CO3)]B10H10 binuclear complexes: Synthesis, structure, and magnetic properties

A redox reaction that occurs in the [Cu2B10H10]/Phen system in CH3CN/DMSO and CH3CN/DMF in air yields a Cu(II) binuclear complex, [(Phen)2Cu(CO3)Cu(Phen)2]2+. The [Cu2(Phen)4(μ-CO3)]B10H10 · 2.5DMSO · 2H2O (I) and [Cu2(Phen)4(μ-CO3)]B10H10 · 4DMF (II) compounds have been isolated and studied by X-ray crystallography at 150 K and EPR at 295 K. Their magnetic properties have been studied in the range 300–2 K. In the cations of both compounds, the bridging CO32− group is bidentately coordinated to two Cu atoms. The cations in I and II have different spatial orientations of the Cu-O bonds: anti-syn and anti-anti, respectively. Compound I has weak magnetic interactions caused by a short Cu…Cu distance (4.441 Å) in the dimer. No exchange coupling is observed in II.

Polymeric heterometallic CuII dimethylmalonate complexes with potassium and cadmium ions

A reaction of (HPiv)2Cu2(Piv)4 with dimethylmalonic acid dipotassium salt (K2Me2mal) leads to the formation of a cage coordination polymer {(μ-H2O)6K8[(μ-H2O)Cu-(μ3,κ2-Me2mal)(μ6,κ2-Me2mal)]2[Cu2(μ5,κ2-Me2mal)2(μ5,κ2-Me2mal)2]}n (1). It was found that when 1 reacted with CdSO4·8H2O in a mixture of EtOH-H2O (3: 1), the potassium ions in 1 were displaced with cadmium(ii) ions with the formation of a heterometallic 1D-polymer [(κ1-H2O)4CdCu(μ,κ2-Me2mal)2]n (2). Compounds 1 and 2 were characterized by X-ray crystallography and ESR spectroscopy.

Dimerization of the copper(II) N -methylbenzoylhydroxamic acid complex in toluene according to EPR data

The structure of copper complexes with N-methylbenzoylhydroxamic acid in toluene at 100 K has been investigated by EPR spectroscopy. In frozen solution, copper hydroxamate exists as one dimeric and two monomeric species. The relative concentrations of these species and their magnetic resonance parameters have been determined by mathematical modeling of the shape of the EPR line.

Thermal stability and products of decomposition of molybdenum(IV) complex with isopropylhydroxylamine [MoO2(i-C3H7NHO)2]

The thermal behavior of the molybdenum(VI) complex with N-isopropylhydroxylamine [MoO2(i-C3H7NHO)2] has been studied. The thermal decomposition of the complex has been found to proceed in a single stage at 185.5°C and to result in non-stoichiometric molybdenum(IV) dioxide.

Structure copper(II) complexes with N-methylacetohydroxamic acid in crystal and solution

The structure of the dimeric complex [CuL2]2 (HL is N-methylacetohydroxamic acid) formed by two square-planar CuL2 moieties with the trans coordination of the ligands has been studied by X-ray crystallography. In methylene chloride at 297 K, the complex exists as two species, which are monomeric as probed by electron paramagnetic resonance. At 80 K, the dimeric and monomeric forms are identified. The relative concentrations of paramagnetic forms and their magnetic resonance parameters have been determined from simulation of EPR spectra.

Isomerism of copper(II) coordination compounds with hydroxamic acids

The structure of CuII complexes with hydroxamic acids Cu[R1N(O)−(O)CR2]2, where R1=Ph, R2=Me; R1=Me, R2=Ph, was studied by ESR spectroscopy. In toluene solutions and low-temperature glasses, the complexes exist as two forms, which were identified ascis-andtrans-isomers. The proportions of the isomers were determined.

Structure of N-substituted copper(II) hydroxamates in crystalline state and frozen solution

Two CuL2 complexes, where L = R1N(O)-(O)CR2, R1 = tert-Bu, R2 = Me (I) and R1 = Me, and R2 = tert-Bu (II) have been structurally studied by X-ray diffraction. According to electron paramagnetic resonance (EPR) data, the complexes exist in dichloromethane at 77 K as two mononuclear isomeric species. The species whose spectrum is described by a spin Hamiltonian with a high hyperfine structure (HFS) constant is a cis-isomer. The species with a smaller HFS constant is classified as a trans-isomer. The trans-isomer of compound II forms an associate with dichloromethane molecules.

Multifrequency EPR and DENR of Polyacetylene Composite

The organo-inorganic composite MoCl1.9 ± 0.1(C30 ± 1H30 ± 1), a product of interaction of MoCl5 with C2H2, has been studied by X- and W-band EPR, double electron nuclear resonance, and W-band electron spin echo spectroscopy. The composite consists of nanosized organometallic molybdenum clusters in the polyacetylene matrix. It has been shown that the composite contains three types of magnetic centers: the first is related to the existence of paramagnetic molybdenum atoms in the polyacetylene matrix, and the other two are paramagnetic defects of the matrix.

Conformation of diethylglyoxime in uranyl complexes

New complexes of uranyl with diethylglyoxime have been synthesized and studied. A feature of these complexes is the tetradentate bridging coordination of the ligand in both cis- and trans-conformations. The structure of organic ligand C6H12N2O2 and binuclear complex (CN3H6)4[(UO2)2(C6H10N2O2)(CO3)(C2O4)2] ∙ H2O have been determined by X-ray diffraction.

Influence of ligand structure on the dimerization of copper(II) N-substituted hydroxamates according to EPR data

Compounds CuL2, where L = R1N(O)–(O)CR2, R1 = C6H5, R2 = C6H5 (I); R1 = C6H5, R2 = CH3 (II); or R1 = 2,4,6-(CH3)3C6H2, R2 = CH3 (III) have been structurally studied by electron paramagnetic resonance (EPR) in methylene chloride. Spectra of two forms of the compounds, which according to the EPR data are mononuclear, are observed in all solutions at room temperature. In frozen solutions of complexes I and II, spectra of monomeric and dimeric forms of the complex are recorded; in a frozen solution of III, spectra of two monomeric forms of the complex. The absence of dimers in the frozen solution of III is explained by the presence of steric hindrances for the rapprochement of monomeric complexes. Relative concentrations of the forms and their magnetic resonance parameters have been determined using mathematical modeling of the shape of the EPR line.