B. E. Zaitsev

Synthesis and luminescent properties of neutral Eu(III) and Gd(III) complexes with 1-(1,5-dimethyl-1h-pyrazol-4-yl)-4,4,4-trifluoro-1,3-butanedione and 4,4,5,5,6,6,6-heptafluoro-1-(1-methyl-1H-pyrazol-4-yl)-1,3-hexanedione

Neutral [EuL3Phen] complexes were synthesized by the reaction of EuCl3 with heterocyclic diketones-1-(1,5-dimethyl-1H-pyrazol-4-yl)-4,4,4-trifluoro-1,3-butanedione and 4,4,5,5,6,6,6-heptafluoro-1-(1-methyl-1H-pyrazol-4-yl)-1,3-hexanedione—and 1,10-phenanthroline (Phen) in an aqueous alcohol solution in the presence of NaOH. The reaction of GdCl3 with the same diketones under analogous conditions, but without adding 1,10-phenanthroline, yielded [GdL3(H2O)2] complexes. The composition of the complexes was determined by elemental analysis, and their optical and luminescent properties were examined.

Synthesis, structure, geometrical, and spectral characteristics of the (HLn)2[CuCl4] complexes. Crystal and molecular structure of bis(2-methylimidazolium) tetrachlorocuprate(II)

The (HLn)2[CuCl4] complexes (where Ln are organic nitrogen-containing bases with n = 1–6) were synthesized. The crystal and molecular structures of bis(2-methylimidazolium) tetrachlorocuprate(II), (HL1)2[CuCl4], were determined. The spectral characteristics of the complexes were measured. The correlations between the degree of distortion of the crystal structure of the tetrachlorocuprate anion and the hydrogen bond parameters and the spectral characteristics of compounds were obtained.

Complexes of 2,3-Dihydroxypyridine with Bivalent Metals. Crystal Structure of 2,3-Dihydroxypyridine

Crystal structure of 2,3-dihydroxypyridine (H2L) is determined. Mn(HL)Cl · H2O, Co(HL)Cl · 2H2O, Cu(HL)Cl, Ni(HL)OH · H2O, and Zn(HL)OH · H2O complexes are synthesized by reacting Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) chlorides with H2L in ethanol solutions and identified. In these complexes, 2,3-dihydroxypyridine is involved in coordination as a monoanion. Spectral parameters of neutral and anionic forms of a ligand are determined and the acidity and complex formation constants are calculated. The compositions of complexes are established.

Crystal structure and spectral characteristics of 2,4,7-trinitro-9-fluorenone

The crystal structure of 2,4,7-trinitro-9-fluorenone C13H5N3O7 is determined by X-ray diffraction analysis. The crystals are monoclinic, a = 4.024(1) Å, b = 16.763(3) Å, c = 18.250(4) Å, β = 96.32(3)°, V = 1223.6(5) Å3, Z = 4, space group P21/c, and R = 0.0640 for 605 reflections with I > 2σ(I). The crystal is built of planar isolated molecules. The compound is characterized using IR and electronic absorption spectroscopy.

Physicochemical properties of solutions of bis(2,3,5,6-tetraoxo-4-nitropyridinate) dianions. Crystal structures of sodium 2,3,5,6-tetraoxo-4-nitropyridinate trihydrate and sodium ammonium bis(2,3,5,6-tetraoxo-4-nitropyridinate) monohydrate

Ammonium 2,3,5,6-tetraoxo-4-nitropyridinate was shown to exist as stable dimers and act as a weak electrolyte in both a crystalline state and aqueous solutions. In a strongly alkaline medium, ammonium cations were successively replaced by sodium cations. The molecular and crystal structures of sodium 2,3,5,6-tetraoxo-4-nitropyridinate trihydrate and sodium ammonium bis(2,3,5,6-tetraoxo-4-nitropyridinate) monohydrate were established, and their spectroscopic characteristics were determined.

Crystal structure and spectral characteristics of 2-methyl-3-chloro-9-hydroxypyrido[1,2-a]pyrimidin-4-one and bis(2-methyl-3-chloro-9-hydroxypyrido[1,2-a]pyrimidin-4-onium) perchlorate

Abstract2-Methyl-3-chloro-9-hydroxypyrido[1,2-a]pyrimidin-4-one (I) and bis(2-methyl-3-chloro-9-hydroxypyrido[1,2-a]pyrimidin-4-onium) perchlorate (Ia) are synthesized and studied by X-ray diffraction and IR spectroscopy. It is shown that compound I exists in the molecular form in crystals and in the zwitterion form in solutions. The structural units of compound Ia are partially protonated centrosymmetric dimeric cations and perchlorate anions. The dimeric cation involves two molecules I in the zwitterion form. These molecules are linked together by a strong symmetric hydrogen bond formed with the participation of a proton located at the inversion center. The structures of a series of pyrido[1,2-a]pyrimidines are investigated and compared. It is demonstrated that the tautomeric equilibrium revealed in solutions of compounds of this class depends on the solvent type and pH of the medium.

Geometric and spectral characteristic of the tetrahalocuprate(II) complexes (HL)2CuX4 (X = Cl, Br). Crystal and molecular structures of bis(2-methylimidazolium) tetrabromocuprate(II)

The crystal and molecular structures of bis(2-methylimidazolium) tetrabromocuprate(II) are determined. The linear dependences of the degree of distortion of the CuBr42− coordination polyhedron on the protonation constant of the organic cation are revealed for the structures with θ < 140°. The dependence of the hydrogen bond parameters (distances H…Br and N…Br, angle NHBr) on the degree of distortion of CuBr42− is shown. The degree of distortion of CuX42− (X = Cl, Br) is determined by the type of the organic cation and is almost the same for the CuBr42− and CuCl42− polyhedra. The empirical equations relating the degree of distortion of CuX42− (X = Cl, Br) and the position of the Cu ← X ligand-to-metal charge-transfer band (νLMCT) are obtained.

Complexation of 2,3-dihydroxyquinaline with some bivalent d metals. Crystal and molecular structures of 2,3-dihydroxyquinoline

The reactions of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Cd with 2,3-dihydroxyquinoline (H2L) were used to synthesize and identify the complexes M(HL)2 · 2H2O (M = Mn, Ni, Cu), Fe(HL)OH · 2H2O, Co(HL)OH · H2O, Cd(H2L)Cl2, where H2L participates in the coordination in the monoanionic or neutral forms with the formation of the chelate cycles. Single crystal was isolated and the crystal structure of H2L was determined. The spectral characteristics of a neutral and anionic form of the ligand were measured, and its complexation with MCl2 was studied in the ethanol solutions. The acidity constant of H2L and the formation constants of the complexes in solutions were calculated.

Synthesis and physicochemical properties of the d metal complexes with 2-phenyl-4-(piperidyl-1)-pyrido[2,3-a]anthraquinone. The molecular and crystal structures of 2-phenyl-4-(piperidyl-1)-pyrido[2,3-a]anthraquinonium-7,12 tetranitrozincate

Two types of complexes of 2-phenyl-4-(piperidyl-1)-pyrido[2,3-a]anthraquinone (L) with transition metals were isolated from neutral acetonitrile and acidified acetonitrile and ethanol solutions and characterized. Metal complexes synthesized at pH = 7 had the composition MCl2L · (CH3CN)n (M = Cu, Co, Ni). The complexes (HL)2[Cu2Cl6] (I), (HL)2[CoCl4] (II), (HL)2[Zn(NO3)4] (III) were obtained at pH = 1–2. The molecular and crystal structure of complex III was determined. Some spectral parameters of L and its complexes were measured.

Complexes of d and f Metals with 2-Methyl-3-hydroxy(amino)pyrido[1,2-a]pyrimidine-4-one. Crystal Structure of 2-Methyl-3-hydroxypyrido[1,2-a]pyrimidine-4-one

Six complexes of scandium(III), lanthanum(III), praseodymium(III), and copper(II) chlorides with 2-methyl-3-hydroxypyrido[1,2-a]pyrimidine-4-one (HL1) and 2-methyl-3-aminopyrido[1,2-a]pyrimidine-4-one (L2), as well as hydrochloride and hydronitrate L2, were isolated. The crystal and molecular structures of HL1 were determined. HL1 in CCl4 solution was shown (IR data) to occur as two forms, namely, neutral and zwitterionic forms. The structures for the complexes isolated were proposed.