E. A. Ugolkova

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.

Synthesis, structure, and ESR spectra of the new heteronuclear complex {Li4(VO)2[(OOC)2C(H)Bu]4(H2O)8}·H2O

The reaction of an aqueous solution of vanadyl sulfate VOSO4·3H2O, butylmalonic acid (H2Bumal = C4H10(COOH)2), and lithium carbonate at pH ∼4–5 gave crystals of the complex Li4(VO)2(Bumal)4(H2O)8]·H2O (1). The structure of complex 1 was established by X-ray diffraction analysis. The molecule of complex 1 consists of two mononuclear bischelate dianionic units {VO(Bumal)2(H2O)} linked by four lithium ions to form the hexanuclear heterometallic {V2Li4} structure. The crystals and an ethanolic solution of compound 1 were studied by ESR spectroscopy.

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.

Unusual structure of new dimethylmalonate coordination polymer with strontium atoms and VO2+ fragments

A reaction of vanadyl sulfate VOSO4·3H2O with dimethylmalonic acid strontium salt led to the coordination polymer {Sr(H2O)8[VO(Me2mal)2]}n (1, Me2mal is the dimethylmalonic acid dianion), in which the carboxylate dianions did not form chelate metallocycles with the vanadyl ions. The complex was studied by ESR spectroscopy. The compound 1 exhibited weak spin-spin exchange interactions of ferromagnetic type between the VIV atoms.

Synthesis and characterization of Mn(II) coordination compounds with 2-(7-bromo-2-oxo-5-phenyl-3H-1,4-benzdiazepin-1-yl)acetohydrazide and its condensation product with pyruvic acid

Complexes of MnCl2 with 2-(7-bromo-2-oxo-5-phenyl-3H-1,4-benzdiazepin-1-yl)acetohydrazide (Hydr) and its condensation product with pyruvic acid (HPv) of composition [Mn(Hydr)2Cl2] (I) and [Mn(HydrHPv)2Cl2] (II) were prepared. The complexes were characterized by conductivity and magnetic susceptibility measurements, IR and ESR spectroscopy.

Copper(II) coordination compounds with 2-(7-bromo-2-oxo-5-phenyl-3H-1,4-benzdiazepin-1-yl)acetohydrazide and products of its condensation with pyruvic acid

Some methods for the synthesis of copper(II) complexes with 2-(7-bromo-2-oxo-5-phenyl-3H-1,4-benzodiazepin-1-yl)acetohydrazide (Hydr) ([Cu(Hydr)(H2O)Cl2]) and products of its condensation with pyruvic acid ([Cu(HydrHPv)(H2O)Cl2] and, with alkalization to pH 8, [Cu(HydrPv)2]) were developed, and the complexes themselves were synthesized. The complexes were characterized by electrical conductivity, magnetic susceptibility, and IR and EPR spectroscopy measurements.

Composition and structure of rhenium(VI) complexes as found by EPR and laser mass spectrometry

Reactions of rhenium with oxymonothiophenols in ReO4−-HCl (H2SO4)-L systems (where L is 3-tert-butyl-2-mercaptophenol or 3-tert-butyl-2-mercapto-6-methylphenol) to form complexes, in which rhenium has an oxidation number of +6, have been studied by means of electron paramagnetic resonance (EPR), spectrophotometry, and surface-assisted laser desorption/ionization methods. The parameters of EPR spectra have been determined, and ion peaks in the mass spectra have been identified. It has been found that the studied complexes are octahedrons distorted in the equatorial plane and the composition of compounds satisfies the Re: L ratio of 1: 3.

Electronic structure of κ-ET2X salts, where “ET” is bis(ethylenedithio) tetrathiafulvalene (BEDT-TTF) molecule

Abstract The electronic structure of κ-ET 2 X salts is studied on the basis of the tight-binding approach for correlated electrons. The evaluated band gap in the paramagnetic state, derived density of states and energy dispersion relations are in agreement with available experimental data and theoretical speculations.

Magnetically active coordination polymers containing VO2+ and Na+ cations linked by substituted malonic acid anions

The interaction of vanadyl sulfate VOSO4·3H2O and dimethylmalonic (H2Me2mal = = C3H6(CO2H)2), butylmalonic (H2Bumal = C4H10(CO2H)2), and cyclobutane-1,1-dicarboxylic (H2cbdc = C4H6(CO2H)2) acids with Na2CO3 at pH ∼4 in aqueous solutions gives crystals of compounds [Na4(VO)2(Me2mal)4(H2O)]n (1), {[Na6(VO)3(Bumal)6(H2O)15]· ·3H2O}n (2), and [Na2(VO)(cbdc)2(H2cbdc)(H2O)3]n (3), whose structures were determined by X-ray diffraction analysis. The formation of 3D (for 1) and 2D (for 2 and 3) polymer networks occurs in crystals of the compounds. These networks are constructed of mononuclear bis-chelate dianionic fragments [VOL2]2− (L is the corresponding dicarboxylic acid dianion) linked by the Na atoms. The magnetic properties of the obtained compounds were studied. The solid samples and solutions of complexes 1–3 were characterized by ESR spectroscopy.

Self-assembly and decay of Mn(II) pivalate–phosphonate complexes

A series of new manganese(II) pivalate–phosphonate complexes with various nuclearities (Mn4, Mn10, and Mn20) under aerobic conditions was synthesized by self-assembly of simple reagents. The constitution of polynuclear architectures is affected by the reaction temperature. The structures of the complexes were determined by single crystal X-ray analysis. Magnetic behavior of the compounds points to dominant antiferromagnetic exchange interactions. Antiferromagnetic coupling with JMn–Mn = −0.097(1) cm−1, gMn = 1.993(1) for an equilateral tetrahedron model simulates the magnetic behavior of the tetranuclear complex Mn4 with a cube-like core.