Synthesis and spectroscopic studies of europium chelate complexes

The synthesis of the mixed complexes of the europium ion with 2-pyridylcarbinol-N-oxide, and 2,2′-dipyridyl and 1,10-phenanthroline were prepared. The compounds, were characterized by means of chemical analyses, vibrational spectra, molar conductivities, and electronic spectra. The emission of the [EuL₃, phen] complex at 10 K is very intense and an assignment of the point symmetry of the Eu(III) ion has been made.     

Coordination of rare-earth elements in complexes with monovacant Wells-Dawson polyoxoanions

The alpha-1 and alpha-2 isomers of the monovacant Wells-Dawson heteropolyoxoanion [P(2)W(17)O(61)](10-) are complexants of trivalent rare-earth (RE) ions and serve to stabilize otherwise reactive tetravalent lanthanide (Ln) and actinide (An) ions in aqueous solution. Aspects of the bonding of Ln ions with alpha-1-[P(2)W(17)O(61)](10-) and alpha-2-[P(2)W(17)O(61)](10-) were investigated to address issues of complex formation and stability. We present structural insights about the Ln(III) coordination environment and hydration in two types of stoichiometric complexes, [Ln(alpha-1-P(2)W(17)O(61))](7-) and [Ln(alpha-2-X(2)W(17)O(61))(2)](17-) (for Ln identical with Sm, Eu, Lu; X identical with P, As). The crystal and molecular structures of [(H(2)O)(4)Lu(alpha-1-P(2)W(17)O(61))](7-) (1) and [Lu(alpha-2-P(2)W(17)O(61))(2)](17-) (2) were solved and refined through use of single-crystal X-ray diffraction. The crystallographic results are supported with corresponding insights from XAFS (X-ray absorption fine structure) for a series of nine solid-state complexes as well as from optical luminescence spectroscopy of the Eu(III) analogues in aqueous solution. All the Ln ions are eight-coordinate with oxygen atoms in a square antiprism arrangement. For the 1:1 stoichiometric Ln/alpha-1-[P(2)W(17)O(61)](10-) complexes, the Ln ions are bound to four O atoms of the lacunary polyoxometalate framework in addition to four O atoms from solvent (water) molecules as [(H(2)O)(4)Ln(alpha-1-P(2)W(17)O(61))](7-). This structure (1) is the first of its kind for any metal complex of alpha-1-[P(2)W(17)O(61)](10-), and the data indicate that the general stoichiometry [(H(2)O)(4)Ln(alpha-1-P(2)W(17)O(61))](7-) is maintained throughout the lanthanide series. For the 1:2 stoichiometric Ln/alpha-2-[X(2)W(17)O(61)](10-) complexes, no water molecules are in the Ln-O(8) coordination sphere. The Ln ions are bound to eight O atoms-four from each of two heteropolyanions-as [Ln(alpha-2-X(2)W(17)O(61))(2)](17-). The average Ln-O interatomic distances decrease across the lanthanide series, consistent with the decreasing Ln ionic radius.     

Synthesis and spectral study of chelate alkenylarenedicarbonyl complexes of Cr,Mo and W

Irradiation of alkenylarene tricarbonyl-chromium, -molybdenum, and -tungsten compounds in which the double bond is separated from the arene moiety by a two- or three-atom bridge results in intramolecular cyclization to give stable chelate alkenylarenedicarbonylmetal complexes. Chelate complexes containing four-atom bridges have low stabilities, and those with monoatomic bridges were not formed at all. Irradiation of styrenetricarbonyl-chromium and -molybdenum leads to dinuclear tricarbonylmetal—dicarbonylmetal complexes. The chelate complexes obtained have been studied by IR, proton NMR, and ¹³C NMR spectroscopy. The electron density distributions and the stereochemistry of the complexes are discussed. With nonsymmetric arenes, diastereoisomers are formed; the predominant isomers have been isolated in the pure form. According to the proton NMR data the double bond in alkenylarenechromium chelates is parallel of nearly parallel to the arene ring plane.     

Synthesis and characterization of the rare-earth complexes with salicylic acid

Seven rare-earth complexes with salicylic acid RE(HSal)₃·nH₂O (HSal = C₇H₅O₃; RE = La-Sm, n = 2; RE = Eu, Gd, n = 1) were synthesized and characterized by elemental analysis, the IR spectrum, and cyclic voltammetry. The constant-volume combustion energies of complexes, Δ_c U, were determined by a precise rotating-bomb calorimeter at 298.15 K. Their standard molar enthalpies of combustion, Δ_c H _m ^o , and standard molar enthalpies of formation, Δ_f H _m ^o , were calculated.     

Synthesis and catalytic properties of rhodium(I) complexes with anionic chelate nitrogen-oxygen ligands

Summary Dicarbonyl complexes of rhodium(I) [Rh(CO)₂(LL)], where LL = salicylaldoximate, 8-oxyquinolinate, glycinate, leucinate, aminophenolate or pyridine carboxylate and [Rh(COD)(LL)], where COD = 1,5-cyclooctadiene, were prepared and characterized by elemental analysis, and i.r. and n.m.r. spectra. Their activity to catalytic hydroformylation of styrene has been evaluated at atmospheric pressure of COH₂(11).     

Electrochemical and electrochromic properties of rare-earth metal diphthalocyanine complexes

The electrochemical and spectroelectrochemical properties of several new rare-earth metal diphthalocyanine complexes with different substituents containing both electron-withdrawing and -donating substituents in the phthalocyanine rings were studied. The influence of structural modification of the phthalocyanine complexes (viz., the nature of the central metal atom and substituents in the phthalocyanine rings and the number of phthalocyanine rings in the complexes) on the total number of redox transitions, their potentials, and spectral characteristics of anionic and cationic forms of the complexes was examined. The potentials of the first anodic and cathodic redox transitions of the diphthalocyanine complexes are in a good linear correlation with the ionic radii of lanthanides. The potentials of the observed redox transitions of the complexes under study correlate well with the sums of Hammett constants for the substituents and the minimum molecular electrostatic potential of the benzene rings in the phthalocyanine moiety, which serves as a measure of electron perturbations introduced by the substituents. The revealed regularities allow the prediction of the redox properties and structure of rare-earth element diphthalocyanine complexes, which are redox-active in a specified potential range.     

Synthesis and spectral characteristics of cyclohexylmethoxy-substituted phthalocyanines of rare-earth elements

New symmetrical metal complexes of the rare-earth element phthalocyanines were synthesized by the reaction of 4,5-bis(cyclohexylmethoxy)phthalonitrile, obtained for the first time, with the rare-earth element salts, as well as starting from the corresponding free phthalocyanine. A correlation between method of the synthesis and the reaction product compositions was studied. Structures of the complexes obtained were confirmed by mass spectrometry, X-ray crystallography, and electronic absorption spectroscopy. All the metal complexes are well soluble in organic solvents. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2343–2349, December, 2007.     

Synthesis and study of rare-earth uranogermanates

A series of M^III(HGeUO₆)₃ · 8H₂O rare-earth uranogermanates (M^III = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er) were prepared by precipitation from solutions under hydrothermal conditions. The compositions and structures of the synthesized compounds were studied, their complete crystallographic and functional similarity were established, and the processes of their dehydration and thermal decomposition were studied on the basis of chemical analysis, X-ray diffraction, IR spectroscopy, and differential scanning calorimetry data.     

Synthesis and physicochemical properties of crystalline tris(ferrocenoyl)acetonate hydrates of some rare-earth elements

Tris(ferrocenoyl)acetonates of some lanthanides were obtained by homophase synthesis. The compositions and structures of the complexes obtained were proved by elemental analysis, electronic absorption and IR spectroscopy. Their solubilities in some aprotic solvents and thermal stabilities (by the thermographic method) were determined. The thermal properties of lanthanide tris(ferrocenoyl)acetonates were compared with those of analogous lanthanide tris(acetyl)acetonates.     

Halide polyhydrates of some rare-earth elements: Synthesis and structures

Scandium, yttrium, lanthanum, cerium, and terbium bromides and iodides of the formulas [(H₂O)₅Sc(μ-OH)₂Sc(H₂O)₅]Br₄ · 2H₂O (I), [(H₂O)₅Sc(μ-OH)₂Sc(H₂O)₅]I₄ (II), [Y(H₂O)₈]Br₃ · 2H₂O (III), [(H₂O)₇La(μ-Br)₂La(H₂O)₇]Br₄ (IV), [Ce(H₂O)₉]I₃ (V), and [Tb(H₂O)₉]I₃ (VI) were obtained and examined using X-ray diffraction and IR and Raman spectroscopy. It was found that the compositions and structures of complexes II and III differ from the literature data. Crystallographic parameters were obtained for isostructural complexes V and VI. It was demonstrated that the conditions of the synthesis and the possibility of protolysis are decisive for the formation of polynuclear oxo and hydroxo complexes of rare-earth metal halides.     

Influence of the composition of compositions based on organic compounds and chelate complexes of aluminun and yridium on their electroluminescent properties

The effect of the composition of electroluminescent compositions based on PEDOT, TPD, Alq₃, and Ir(PPy)₃, the structure of the cathode (Al, CaMg/Ag, Al/Ag), and the possibility of forming of emitting layers (thermovacuum deposition and centrifugation) on their current-voltage, voltage-brightness, and spectral characteristics has been studied. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 45, No. 1, pp. 54–58, January–February, 2009.     

一种新型毛细管气相色谱固定相的合成及其色谱性能研究

以单（6-O-对甲苯磺酰基）-β-环糊精为中间体，合成了L-苯丙氨酸衍生化的β-环糊精。为了提高其涂渍性能，使其能更好地适用于气相色谱分析，用乙酸酐将其乙酰化，得到了一种橙黄色的粘稠液体。产物用红外光谱进行表征并用热重分析测试其热稳定性能。将其作为一种新型的气相色谱手性固定相动态涂渍在石英毛细管柱。在该毛细管上对一系列化合物的分离和保留行为进行了研究，结果表明该固定相对位置异构体和对映异构体具有较好的分离效果，显示了较强的立体选择性和较好的手性分离效果。     

Hexadecapropyloxy-substituted diphthalocyanine complexes of rare-earth elements: synthesis,spectroscopic and electrochemical studies

Hexadecapropyloxy-substituted diphthalocyanine complexes of rare-earth elements (REE = Lu, Tm, Sm) were synthesized. The new symmetrically substituted diphthalocyanine complexes prepared starting from 4,5-dipropyloxyphthalodinitrile (phthalogen) are characterized by better solubilities compared to the known hexadecamethyl-substituted diphthalocyanine complexes of the same REE. Spectral and electrochemical characteristics of the complexes were studied. The compounds can be used as materials for high-contrast electrochromic devices.