E. S. Bazhina

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.

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.

The formation of polymeric structures in the M2+–VO2+ systems (M2+ = Sr2+, Ca2+) containing substituted malonate anions

The synthesis and crystal structures of the polymeric compounds of vanadyl (VO2+) and alkaline-earth metal cations (Sr2+ and Ca2+) with the anions of substituted malonic acid analogs, R(COOH)2, were described. Reactions of vanadyl sulfate (VOSO4 · 3H2O) with calcium and strontium salts of cyclopropane-1,1-dicarboxylic (H2Cpdc, C3H4(COOH)2), cyclobutane-1,1-dicarboxylic (H2Cbdc, C4H6(COOH)2), and butylmalonic acids (H2BuMal, C4H10(COOH)2) gave polymeric structures with different (from 1D to 3D) dimensionality. The structure and dimensionality of the compound depends on the size of the substituent in the carboxylate dianion and the radius of the alkaline-earth metal ion.

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.

Novel oxovanadium(IV) heterochelate complexes: synthesis, structure, ESR spectra, and photoluminescence properties

The reactions of oxovanadium(iv) salts with dimethylmalonate anions (H2Dmm — C3H6(COOH)2) and chelating N-donor ligands (2,2′:6′,2″-terpyridine (terpy), 2,2′-bipyridine (bpy)) led to the formation of new mononuclear heterochelate complexes [VO(Dmm)(terpy)]·4H2O (1) and [VO(Dmm)(bpy)(H2O)] (2). The structures of the synthesized compounds were determined by X-ray diffraction. The ESR spectra of the compounds at 293 and 100 K were analyzed and simulated. The photoluminescence properties were investigated.

The effect of the substituents in the malonate anion and the solvent molecules on the structures of novel coordination polymers [Li2VO(R2mal)2] n

Reactions of vanadyl sulfate (VOSO4∙3H2O) with dimethylmalonic (H2Me2mal = = C3H6(CO2H)2), cyclobutane-1,1-dicarboxylic (H2cbdc = C4H6(CO2H)2), or butylmalonic acid (H2Bumal = C4H10(CO2H)2) and Li2CO3 in a ratio of 1: 2: 2 afforded novel coordination polymers of similar compositions ([Li2(VO)(Me2mal)2]n (1), [Li2(VO)(Me2mal)2(EtOH)-(H2O)]n (2), [Li4(VO)2(cbdc)4(H2O)7]n (3), and [Li2(VO)(Bumal)2(H2O)5.5]n (4)) but different structures. The crystal structures of the compounds containing the Me2mal2– and Bumal2– anions depend on the solvent nature.

Lanthanide(III) (Eu, Gd, Tb, Dy) Complexes Derived from 4-(Pyridin-2-yl)methyleneamino-1,2,4-triazole: Crystal Structure, Magnetic Properties, and Photoluminescence

The reaction of lanthanide(III) nitrates with 4-(pyridin-2-yl)methyleneamino-1,2,4-triazole (L) was studied. The compounds [Ln(NO3 )3 (H2 O)3 ]⋅2 L, in which Ln=Eu (1), Gd (2), Tb (3), or Dy (4), obtained in a mixture of MeCN/EtOH have the same structure, as shown by XRD. In the crystals of these compounds, the mononuclear complex units [Ln(NO3 )3 (H2 O)3 ] are linked to L molecules through intermolecular hydrogen-bonding interactions to form a 2D polymeric supramolecular architecture. An investigation into the optical characteristics of the Eu3+ -, Tb3+ -, and Dy3+ -containing compounds (1, 3, and 4) showed that these complexes displayed metal-centered luminescence. According to magnetic measurements, compound 4 exhibits single-ion magnet behavior, with ΔEeff /kB =86 K in a field of 1500 Oe.

Examples of cation exchange in new ionic oxovanadium(IV) complexes with anions of cyclobutane-1,1-dicarboxylic acid

The results on the synthesis and study of the crystal structures of compounds based on anionic fragments {VO(Cbdc)2}2– formed by oxovanadium(IV) (vanadyl, VO2+) and two chelate-bound anions of cyclobutane-1,1-dicarboxylic acid (H2Cbdc = C4H6(COOH)2) are presented. The use of ammonium cation NH4+ as a counterion in the synthesis leads to the formation of the mononuclear complex (NH4)2[VO(Сbdc)2(H2O)] · 2H2O (I). In the case of K+ cation, compound [K4(VO)2(Сbdc)4(H2O)4]n (II) with the 3D polymeric crystal structure is formed. The reaction of compound II with Mg(NO3)2 · 6H2O in an aqueous solution involves the partial substitution of K+ by Mg2+ cations to form 1D polymeric compound {[KMg0.5(VO)(Сbdc)2(H2O)6.5] · 3H2O}n (III), while a similar reaction of compound I does not afford the product of substitution of NH4+ by Mg2+ cations (CIF files CCDC 1551021–1551023 for compounds I–III, respectively).