Photo-Absorption and photochemical decomposition of copper and alkaline-earth ß-diketonates as source gases of high-Tc superconducting films

For low-temperature deposition of oxide films relating to Bi-Sr-Ca-Cu-O superconductors, photo-absorption and -decomposition properties were examined with respect to copper and alkaline-earth ß-diketonates. It was confirmed that all ß-diketonates examined were promising as source materials for photochemical vapour deposition (photo-CVD) using a low-pressure mercury lamp, in view of their large light absorption coefficients at wavelength 254 nm. The light irradiation was effective for the formation of highly crystalline oxide films at temperatures below 600 °C. By combining two sources, Ca₂CuO₃ and SrCuO₂ films were prepared. Photo-CVD of c-axis oriented Bi₂Sr₂CuO_x film was achieved by the irradiation of ternary sources of Bi(C₆H₅)₃ and strontium and copper ß-diketonates at 500 °C.     

Structure and energy studies of β-diketonates. XIII. Molecular structure of gadolinium tris-hexafluoroacetylacetonate Gd(C5O2HF6)3

In a mass spectrometric study, it was found that the saturated vapor over gadolinium tris-hexafluoroacetylacetonate Gd(C₅O₂HF₆)₃ contains molecular forms with a mass exceeding the mass of the dimer. The vapor overheated to 250–300°C contains only the monomer form. Simultaneous electron diffraction and mass spectrometric experiment aimed at investigating the structure of the Gd(hfa)₃ monomer molecule was carried out at 284(5)°C. The Gd(hfa)₃ molecule was found to have the symmetry of the equilibrium D ₃ configuration. The basic structural parameters are r _h1(Gd-O) = 2.291(10) Å, r _h1(O-C) = 1.257(10) Å, r _h1(C-C_r) = 1.404(6) Å, r _h1(C_F-F)_av = 1.341(3) Å, ∠OGdO = 72.8(0.4)°. The GdO₆ coordination polyhedron has the structure of a distorted antiprism. The rotation angle of the O-O-O trigonal faces relative to their position in a regular prism is 18.7(0.9)°. Quantum chemical calculations (HF/SBK, 6-31G*) generally reproduce the experimental structure, but the Gd-O internuclear distance is exaggerated by 0.04 Å.     

Synthesis and X-ray structural study of octa-coordinated hexafluoroacetylacetone hafnium(IV) complex

Hexafluoroacetylacetonate hafnium(IV) complex has been synthesized and studied by X-ray structural analysis. Crystal data for C₃₀H₈F₃₆Hf₂O₁₄ are: a = 12.957(3) Å, b = 16.687(3) Å, c = 12.398(3) Å, β = 108.97°, space group P2₁/c, Z = 2, d _calc = 2.137 g/cm³, R = 0.047. The molecular structure is built from discrete binuclear molecules of Hf₂(OH)₂(hfac)₆ composition; the Hf...Hf distance in dimer is 3.533 Å. The structural units are connected by van der Waals interactions in the crystal.     

Crystal structure of oxotitanium(IV) 2,2,6,6-tetramethyl-3,5-heptanedionate

The structure of titanyl dipivalylmethanate TiO(dpm)₂ has been studied by X-ray diffraction analysis. The compound has a molecular structure formed by isolated centrosymmetrical dimers [TiO(dpm)₂]₂; the unit cell contains two structurally related, crystallographically unique binuclear molecules. The Ti...Ti distance in the dimer is 2.73 Å. Crystal data for Ti₂C₃₆H₇₆O₁₀: a = 32.477(6) Å, b = 14.409(3) Å, c = 25.630(5) Å; β = 107.82(3)°, space group C2/c, Z = 8, d _calc = 1.002 g/cm³.     

A brief study of the supercritical fluid chromatographic behavior of lanthanide β-diketonates

The chromatographic behaviors of lanthanide chelates of acetylacetone (ACAC), trifluoroacetylacetone (TFA), thenoyltrifluoroacetone (TTA), dipivaloylmethane (THD), 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione (FOD), and the thenoyltrifluoroacetonepyridine (TTA·Py) adduct were investigated using packed column supercritical fluid chromatography. Mobile phases consisting of neat and alcohol modified CO₂ were used with a phenyl packed stationary phase. Lanthanide complexes of ACAC, THD, and FOD were shown to have better chromatographic performance compared to the corresponding chelates with TFA, TTA, and TTA·Py. In particular, TTA complexes such as Eu(TTA)₃ showed characteristic thermal decomposition in the mobile phase at elevated temperature. In addition, retention behavior was found to be a temperature dependent function of volatility and solubility for all chelates studied.     

Crystal structure of copper(II) bis-hexafluoroacetylacetonate

An X-ray diffraction investigation has performed for copper(II) bis-hexafluoroacetylacetonate (Bruker AXS P4 automatic diffractometer, MoK radiation, t = –25°C). Crystal data for C₁₀H₂CuF₁₂O₄: a = 5.530(1) Å, b = 6.038(1) Å, c = 11.266(2) Å, = 95.948(3)°, = 101.743(3)°, = 92.298(3)°, space group; P1, V = 365.6(1) ų, Z = 1, d _calc = 2.169 g/cm³. The square-planar environment of the copper atom (Cu-O_av 1.912 Å, O-Cu-O_av 93°) is completed to bipyramidal by two fluorine atoms of the neighboring molecules, Cu...F 2.71 Å and 2.75 Å.Original Russian Text Copyright © 2004 by S. A. Gromilov, I. A. Baidina, P. A. Stabnikov, and G. V. RomanenkoTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 502–507, May–June 2004.     

Crystal structure of boron difluoride 3-phenylthiopentane-2,4-dionate. π stacking interactions and luminescence of boron difluoride acetyl acetonates

The crystal structure of boron difluoride 3-phenylthiopentane-2,4-dionate was determined. The relationship between the structure and luminescent properties is traced in the series of boron difluoride acetyl acetonates (acetyl acetonate, phenylacetyl acetonate, and phenylthioacetyl acetonate). The presence of the π stacking interactions in boron difluoride phenylthioacetyl acetonate crystals leads to increased intensity and bathochromic shift of the fluorescence band.     

金属β－二酮化合物用于MOCVD法生长铁电氧化物薄膜

对用于MOCVD法生长铁电氧化物薄膜的金属β－二酮化合物的制备、结构及性质进行了评述，对它们在生长铁电薄膜中的应用现状进行了介绍，并对它们的应用前景作了展望。     

Luminescence quenching of lanthanides in complexes with β-diketones containing different fluorinated radicals

It is shown that luminescence quenching of lanthanide (Ln) ions by water molecules (OH-oscillators) entering the first coordination sphere of a complex decreases as the chain of the fluorinated radical lengthens from CF₃ to C₆F₁₃. The amounts of water molecules in binary and different-ligand Eu complexes with some fluoro derivatives of acetyl acetone are determined. It is established that, unlike OH-oscillators, the elimination of hydrogen oscillations at the central carbon atom by β-diketone deuteration provides the same increase (1.1–1.2 fold) in luminescence intensity in all the investigated Eu complex compounds. A. V. Bogatskii Physicotechnical Institute, National Academy of Sciences of Ukraine, 86, Lyustdorfskaya Read, Odessa, 270080, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 2, pp. 217–220, March–April, 1997.     

Luminescence of praseodymium (III) in solutions of mixed-ligand complexes with β-diketones

We have found that it is possible to enhance the luminescence of Pr(III) in solutions of complexes with β-diketones: acetylacetone derivatives containing fluoroalkyl substituents of different lengths and structures. We have established that in the presence of organic solvents, second (additional) ligands, and surfactants shielding the central ion from the quenching effect of the water molecules (OH oscillators), the intensity of luminescence for Pr(III) increases by a factor of 65, 38, and 45 respectively. In this case, cationic surfactants form ionic associates with Pr(III) β-diketonates, with incorporation of one more β-diketone molecule (ratio Pr:β-diketonate:surfactant = 1:4:1). As a result of suppression of intramolecular energy losses in solutions of Pr(III) β-diketonates, it is possible to observe its rather intense luminescence at 605 nm (the transition ¹D₂ → ³H₄), 612 nm (³P₀ → ³H₆), and 646 nm (³P₀ → 3F₂). __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 746–750, November–December, 2006.