S. A. Prokhorova

Crystal and molecular structure of monomeric yttrium(III) dipivalylmethanate. Arrangement of adsorbed layers

Crystal structure of monomeric yttrium(III) dipivalylmethanate, YO6C33H57, has been studied by X-ray diffraction. Crystal data: a=17.868(3), b=9.977(2), c=10.633(2) Å, V=1895.7 Å3, space group Pmn21, Z=2, dcalc=1.116, dexp=1.119 g/cm3. The compound has a molecular structure and consists of monomeric molecules with a proper symmetry plane m. In the metallocycle lying in this plane, Y-O interatomic distances and O−Y−O bond angles markedly differ from the similar distances and angles in the other two planes. The average Y−O, O−C, and C−C distances are 2.22, 1.25, and 1.46 Å, respectively. As a result of comparative crystal-chemical analysis carried out for related compounds, the coordination polyhedra around the yttrium atoms were found to be trigonal prisms formed by six oxygen atoms of three bidentate ligands. Layers ∼1 μm thick were obtained by vapor condensation of the complex on different supports; the layers were investigated by XRD. Irrespective of the type of support, the layers are oriented polycrystalline films with [001] texture axes. Arrangement of the adsorbed molecules of the complex is analyzed. The layers are self-organized into close-packed structures with C(CH3)3 groups oriented toward supports.

CRYSTAL STRUCTURE OF LEAD(II) DIPIVALOYLMETHANATE

The volatile complex of lead(II) with 2,2,6,6-tetramethylheptane-3,5-dione is investigated by X-ray diffractometry. Crystal data: a = 10.901(2), b = 21489(4), c = 10.203(2) å, space group Pccn (N 56), V = 2503.4(8) å3, M = 573.74, Z = 4, dcalc = 2.522 g/cm3. The crystal structure is of molecular type; the molecule of the complex has a nonplanar structure. The lead atom is coordinated by four oxygen atoms of the two bidentate ligands. Films of the complex on substrates of Si and SiO2 single crystals, melted quartz, and glass were obtained by thermal evaporation in vacuum. X-Ray diffraction analysis of the polycrystals and films of the complex showed that the films are distinctly textured along the b axis.

Optical characteristics of nickel and boron carbonitride films in Si(100)/Ni/BC x N y structures

The optical characteristics of nickel films deposited on Si(100) substrates by vacuum thermal evaporation have been studied. The thickness and optical constants of the films are determined using monochromatic zero ellipsometry, while the inverse problems are solved within the three-layer optical model of the samples. It is shown that thermal annealing leads to a change in the optical constants of nickel films in the heating-temperature range of 500–900°C. Boron carbonitride layers deposited on silicon substrates with a nickel sublayer are analyzed within multilayer optical models, which make it possible to determine the refractive index and absorption coefficient distributions along the thickness of the synthesized Si(100)/Ni/BCxNy structure.

STRUCTURAL ARRANGEMENT OF LAYERS IN SOME OCTAORGANYLSILSESQUIOXANES

Thick (≈0.2–1 μm) layers of octaorganylsilsesquioxanes [RSiO1.5]8, where R is CH3, C2H3, and C2H5, were obtained by vacuum deposition and studied by X-ray diffractometry (DRON-3M, R=192 mm, CuKα radiation). Irrespective of the type of support, the layers are ideally oriented polycrystalline films with the [001] texture axis. Structural arrangement of the layers is analyzed on the basis of the crystal data. Orientation of the terminal atomic groups on the surface of the layer is established. It is shown that it is possible to adjust the scale of the layer pattern. Two-layer compositions— Cu(II) β-diketonates and phthalocyanines on octaorganylsilsesquioxane supports and vice versa — with preserved orientations of the films were obtained.

Crystal Structures of [Dy(dpm)3]2 and Dy(dpm)3, Luminescent and X-Ray Fluorescent Study of Lanthanide(III) Tris-Dipivaloylmethanates

Crystal structures of [Dy(dpm)3]2 (1) at 155(2) K (space group P21/n, a = 12.2191(3) Å, b = 27.6044(6) Å, с = 21.8615(5) Å, β = 105.172(1)°, V = 7116.9(3) Å3, Z = 4) and Dy(dpm)3 (2) at 200(2) K (space group Pmn21, a = 17.8741(7) Å, b = 10.5639(4) Å, с = 9.8336(4) Å, V = 1856.78(13) Å3, Z = 2) are determined. The structure of complex 1 is similar to the previously known dimeric packings [Ln(dpm)3]2 (Ln = La, Pr, Nd, Eu, Gd, Tb). Complex 2 is isostructural to the previously studied molecular complexes Er(dpm)3 and Lu(dpm)3. At room temperature the luminescence quantum yield (QY) of Tb(dpm)3 is found to reach 77% and that of Dy(dpm)3 is 5%, while for the other Lu(dpm)3 complexes, where Ln = Pr, Nd, Sm, Eu, Gd, Ho, Er, Tm, Yb, QY is below 1%. A series of [Tb(dpm)3]2 and Dy(dpm)3 solid solutions is obtained by evaporating mixtures from solutions. Molecular films of these complexes on Si, Cu, Ni, Ti, KBr substrates are obtained by vacuum deposition.

Composition and structure of silicon carbonitride layers grown on Si(100)/(Fe, N, Co) substrates

The phase and chemical composition of silicon carbonitride films obtained by plasma-enhanced chemical vapor deposition on Si(100) substrates and the same substrates covered by a layer of (Fe, Ni, Co) alloy is studied. It is shown that substrate metallization practically does not change the chemical composition of the film, but affects the ratio phases present in the film and the film nanostructure.

X-ray spectroscopic study of the electronic structure of boron carbonitride films obtained by chemical vapor deposition on Co/Si and CoO x /Si substrates

Boron carbonitride films are synthesized by chemical vapor deposition from a mixture of triethylamine borane and ammonia on a metallic or oxidized cobalt sublayer sprayed over Si(100) substrates. Scanning electron microscopy shows that the surface of a BCxNy/Co/Si sample has a homogeneous fine-grained structure; filamentous entities are found on the surface of the BCxNy/CoOx/Si sample. The electronic structure of the films is investigated by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS). An analysis of the spectra shows that BCxNy films are composed of graphite and hexagonal boron nitride (h-BN) regions and complex BCxNyOz components with B-C, N-C, B-O, N-O, and C-O bonds. The deposition of the BCxNy film on the oxidized Co sublayer results in an increase in the number of C-O, N-O, B-O, and C-N bonds and a decrease of the graphite and h-BN components and in the number of C-B bonds. The XPS data are used to estimate the surface elemental composition of the BCxNy/CoOx/Si sample. It is found that the film consists of 66 at.% graphite component and 3 at.% h-BN; the proportion of complex C0.46B0.11N0.05O0.38 components is 31 at.%.

Synthesis, X-ray diffraction study, and crystal structure analysis of novel copper Alkoxy-β-diketonates: bis(6,2-dimethyl-6-methoxy-3,5-heptanedionato) copper(II) and bis(1-phenyl-4-methyl-4-methoxy-1,3-pentanedionato) copper(II)

This article is a continuation of the structural study of Cu(II) complexes with alkoxy-β-diketones [1]. Alkoxy-β-diketones, possessing the same complexing ability as classical β-diketones, are more accessible and inexpensive ligands. In some properties (e.g., volatility), metal complexes with these ligands are closely related to metal β-diketonates and can effectively replace them in some important coating methods, including the MOCVD method.