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.     

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 (1<Emphasis Type="Italic">H</Emphasis>-Benzo[<Emphasis Type="Italic">d</Emphasis>]imidazol-2-yl)(3,3-dimethyl-3,4-dihydroisoquinolin-1-yl)methanone (L). complex formation of copper(II) and cobalt(II) chlorides with L

(1H-Benzo[d]imidazol-2-yl)(3,3-dimethyl-3,4-dihydroisoquinolin-1-yl)methanone (L) and its complexes with copper and cobalt chlorides [CuLCl₂] (I) and [CoLCl₂] (II) are synthesized and studied by IR spectroscopy. The structure of molecule L is determined by X-ray diffraction analysis. Molecule L crystallizes as a cis-trans isomer. The dihydroisoquinoline (A) and benzimidazole (B) fragments lie in the mutually perpendicular planes. The N-C bond lengths of fragment A (double bond N(1)-C(1) 1.278(3) Å, ordinary bond N(1)-C(9) 1.490(3) Å) differ noticeably. The N-C bond lengths in fragment B range from 1.327(4) to 1.389(4) Å. The C=O bond is 1.218(3) Å According to the data of IR spectroscopy and X-ray diffraction analysis, complexes I and II are assumed to have different structures with different coordination modes to the metal atom of molecule L: through the imine atoms N(1) and N(2) of fragments A and B in I and through the N(1) atom of the dihydroisoquinoline fragment and the O atom of the carbonyl group in II.     

Nematic liquid crystals in frequency and amplitude modulated electric fields

In this paper we study peculiarities of behaviour of a nematic liquid crystal (NLC) in an electric field consisting of two harmonics with different amplitudes and frequencies. The most interesting result is the experimental observation of high frequency, stabilization of a low frequency electrohydrodynamic instability in the NLC. A method of measurement of the one frequency instability threshold has been proposed. The beating regime of the two frequency electric field was also studied. The theory developed provides an explanation for all the experimental results.     

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.     

Intramolecular Interactions of Phosphor-Containing Groups with an Aromatic Fragment in Different Conformations

Abstract

Geometrical and electronic structure of conformers was studied by optical spectroscopy and quantum chemistry methods. The interaction mechanism of phosphor-containing groups with an aromatic fragment in YC₆H₄PX₂ (Y = H, Cl, Me, OMe, NMe₂, C(O)OR; × = Alk, OAlk, NAlk₂, Cl) and YC₆H₄P(Z)X₂ (Y = H, C1, Me, OMe, NMe₂; × = Alk, OAlk, NAlk₂, F, C1; Z = O, S) compounds is discussed. In case of bisector conformation (A), where the benzene ring plane coincides with a XPX-angle bisectrix, ll-acceptor action of phosphorus-containing groups increases with X varying in a series: Alk <NAlk₂ ≈ OAlk ≤ F4 << C1. These properties are displayed in ground and excited states of molecules, and are determined by interaction of PX₂ and P(Z)X₂ vacant group orbitals antisymmetric with respect to bisector plane with aromatic fragment π-orbitals. For phosphorchloride groups [sgrave]-π-conjugation dominates and the d-π-conjugation contribution is small. π-acceptor effect for P(0)X₂is weaker than for PX₂ and P(S)X₂ groups (especially in excited states) which is due to competitive transfer of electron density from oxygen to PX₂ fragment. In case of the gonal conformation (B) where benzene ring and bisector plane of PX₂ fragment are perpendicular, π-donor effect of PAlk₂ group is found to be 2–4 times weaker than for NAlk₂. According to quantum-chemical calculations with the MNDO method ArPX₂ the stabilization of conformer B for ArPX₂ increases in a series X: C1 <C=N <F <H <CH₃; and for ArP(0)X₂ the main conformation is (A).     

Specific features of the structures of d 2-Rhenium(V) monomeric octahedral oxo complexes: I. Structure of d 2-Re(V) mono-oxo compounds with halogen ligands trans-positioned to O(oxo) ligands

The specific features of the structure of rhenium(V) mononuclear octahedral mono-oxo complexes with halogen ligands (F, Cl, Br), trans-positioned to multiply bonded oxo ligands, are considered.     

Synthesis and crystal and molecular structures of new copper and zinc complexes with aza-14-crown-4 ether having di(α-pyridyl)-substituted bispidine subunit

The complexes [Cu(L)(H₂O)](ClO₄)₂ · 2H₂O (I) and [Zn(L)Cl₂] · C₂H₅OH (II), where L is the macrocyclic substituted aza-14-crown-4 ether molecule containing di(α-pyridyl)bispidine insert, were synthesized and studied by X-ray diffraction. The Cu atoms in complex I and the Zn atoms in complex II have equal coordination numbers of 5 and different highly distorted polyhedra (the CuN₄O tetragonal pyramid and ZnN₃Cl₂ trigonal bipyramid). Ligand L in structure I performs the tetradentate tetrachelate (4N) structural function and in II, it performs the tridentate bis-chelate (3N) function. The key difference between the structures of complexes I and II is determined by different conformations of both the aza-macrocycles and bispidine substituents of ligand L.     

Ionic mobility in ammonium-rubidium heptafluorozirconate (NH<Subscript>4</Subscript>)<Subscript>2.4</Subscript>Rb<Subscript>0.6</Subscript>ZrF<Subscript>7</Subscript> by (<Superscript>1</Superscript>H, <Superscript>19</Superscript>F) NMR data

NMR (¹⁹F, ¹H) methods are used to study ionic mobility in heptafluorozirconate (NH₄)_2.4Rb_0.6ZrF₇ in a range of temperatures from 150 K to 430 K. Types of ionic movements are determined, and their activation energy is evaluated. As a result of a phase transition a modification forms in which diffusion in the ammonium sublattice and isotropic reorientations of ZrF ₇ ^3? complex anions are observed. According to preliminary data, due to diffusion of ammonium ions the compound has relatively high ionic conductivity (σ ≈ 8.3 × 10^?5 S/cm at 423 K).