Synthesis, properties, and crystal structure of the tin(IV) complex with N-(2-hydroxyethyl)ethylenediaminetriacetic acid [Sn(μ-Hedtra)(μ-OH)SnCl3(H2O)] · 3H2O

The binuclear tin(IV) complex with N-(2-hydroxyethyl)ethylenediamine-N,N′,N′-triacetic acid (H₄Hedtra) is synthesized. The compound is characterized by elemental analysis, thermogravimetry, and IR spectroscopy. An X-ray diffraction analysis of complex Sn(μ-Hedtra)(μ-OH)SnCl₃(H₂O)] · 3H₂O (I) is carried out. Structure I is formed by the binuclear complexes and molecules of water of crystallization. One of the tin atoms coordinates six “active” sites Hedtra^4? (the alcohol branch is deprotonated and forms a bridge between two tin atoms) and the bridging hydroxo group. The polyhedron is a pentagonal bipyramid. The octahedral environment of the second tin atom is formed by two bridging oxygen atoms, three chlorine atoms (fac isomer), and a coordination water molecule.     

Ion-selective properties of 1,8-bis [2-(dihydroxyphosphinyl)phenoxy]-3,6-dioxaoctane (H4L3), synthesis and vibrational spectra of copper and zinc complexes with H4L3, and crystal and molecular structure of [Cu(H4L3)(H2O)3][(H2L3)(H2O)]

The ion-selective properties of 1,8-bis[2-(dihydroxyphosphinyl)phenoxy]-3,6-dioxaoctane (H₄L³) have been studied and its potentiometric selectivity coefficients have been determined. New complexes [Cu(H₄L³)(H₂O)₃][(H₂L³)(H₂O)] (I) and Zn(H₄L³)(H₂L³) · 3H₂O, and Cu(H₂L³) · 2(H₂O) have been synthesized and characterized. The crystal and molecular structure of I has been determined by X-ray crystallography and vibrational spectroscopy. The crystals are monoclinic, a = 10.279(5) Å, b = 26.532(13) Å, c = 8.399(4) Å, β = 99.270(8)°, V = 2260.8(7) ų, Z = 2, space group Cm, R = 0.0347 for 4325 reflections with I > 2σ(I). Ionic compound I is composed of the [Cu(H₄L³)(H₂O)₃]²⁺ complex cations and [(H₂L³)(H₂O)]^2? anions. In the cation, the Cu²⁺ cation located in the m plane is bound to a tetragonal pyramidal (TP) array. The equatorial plane of the TP is formed by two phosphoryl oxygen atoms of the podand (Cu(1)-O, 1.921(2) Å) and two O atoms of two water molecules (av. Cu(1)-O, 1.981(3) Å). The third water molecule is at the axial vertex of the TP at a considerably larger distance (Cu(1)-O, 2.139(3) Å). The anion is of the host-guest type. The host is the deprotonated podand (H₂L³)^2?, and the guest is the water molecule. The latter is bound to the terminal hydroxyl groups of two phosphoryl groups of the podand by two acceptor hydrogen bonds and to two central ether oxygen atoms of the (H₂L³)^2? anion by one donor bifurcated hydrogen bond. The cations and anions in the structure are linked by hydrogen bonds to form chains parallel to the c axis.     

Synthesis and crystal structure of the sodium complex with 2-(diphenylacetyl)indandione-1,3

The sodium complex with 2-(diphenylacetyl)indandione-1,3 (HL) have been synthesized and studied by X-ray diffraction analysis. Crystals of [Na₄(H₂O)₄L₄] (I) precipitated from aqueous acetone are monoclinic, Z = 2, space group P2₁/c, a = 12.171(1) Å, b = 10.527(1) Å, c = 29.777(2) Å, β = 97.455(1)°. The structure of compound I is based on a centrosymmetric tetranuclear [Na₄O₁₂] cage. Two central Na(2) atoms are coordinated to four O atoms of two L ligands. The central and peripheral atom polyhedrons [Na(2)O₆] and [Na(1)O₅] are joined by a common edge formed by two O atoms of two L ligands. Tetranuclear moieties are joined into the framework by hydrogen bonds, numerous C-H-π contacts, and π-π stacking-contacts between the conjugated and aromatic ligand systems of neighboring tetramers.     

Bis(citrato)hydroxogermanic(IV) acid dimer [H5O2][Ge(H2Cit)(H2.5Cit)(OH)]2 · 2CH3COOH · 2H2O: Synthesis, properties, and crystal and molecular structure

Bis(citrato)hydroxogermanic(IV) acid was obtained for the first time in the complex [H₅O₂][Ge(H₂Cit)(H_2.5Cit)(OH)]₂ · 2CH₃COOH · 2H₂O (H₄Cit is citric acid). The complex was characterized by chemical analysis, X-ray powder diffraction, TGA, and IR spectroscopy. Complex I was studied by X-ray crystallography. The crystals are triclinic; a = 10.0651(4) ?, b = 10.1918(4) ?, c = 10.5838(4) ?, α = 85.0110(10)°, β = 85.2170(10)°, γ = 86.7670(10)°, V = 1076.50(7) ?³, Z = 1, space group P[`1]P\bar 1, R1 = 0.0353 for 5709 reflections with I > 2σ(I). Complex I is composed of centrosymmetric dimeric complex anions [Ge₂(H₂Cit)₂(H_2.5Cit)₂(OH)₂]⁻, dioxonium cations [H₅O₂]⁺, and acetic acid and water molecules of crystallization. The coordination polyhedron of the Ge atom is a trigonal bipyramid. Its equatorial plane comprises two O atoms of the deprotonated alcohol groups of two ligands H₂Cit (A) and H_2.5Cit (B) and the O atom of the terminal OH group (Ge-O, 1.7585–1.7754 ?; O_eqGe(1)O_eq, 116.26°–127.64°). The axial positions are occupied by the carboxy O atom of the deprotonated carboxylate group of the α branch of ligand A (α-Ge-O(C)(carb), 1.8882(12) ?)) and the carbonyl O atom of the hemiprotonated acetate α branch of ligand B (α-Ge-O(C) 1.9615(12) ?, O(1)Ge(1)O(8) 170.47(5)°). In structure I, the complex dianion, the cation, and acetic acid and water molecules are united through hydrogen bonds into a three-dimensional framework.     

Higher borides and oxygen-enriched Mg–B–O inclusions as possible pinning centers in nanostructural magnesium diboride and the influence of additives on their formation

The study of high pressure (2 GPa) synthesized MgB₂-based materials allows us to conclude that higher borides (with near MgB₁₂ stoichiometry) and oxygen-enriched Mg–B–O inclusions can be pinning centers in nanostructural magnesium diboride matrix (with average grain sizes of 15–37 nm). It has been established that additions of Ti or SiC as well as manufacturing temperature can affect the size, amount and distribution of these inclusions in the material structure and thus, influence critical current density. The superconducting behavior of materials with near MgB₁₂ stoichiometry of matrix is discussed.