Home – Home – Jornals – Journal of Structural Chemistry 2013 number 4

Within the calculation at MR2/6-311++G (d,p) and the analysis was conducted QTAIM structural investigation of 2,6-bis [2-(1H-pyrrol-2-yl) vinyl]-pyridine and 2,5-bis [2-(pyridin-2-yl) vinyl]-1H-pyrrole. Found that the molecule is formed in a first symmetrical three-center hydrogen bond, the components of which are substantially weakened in comparison with two-centered H-bond in the Z-isomer of 2-[2-(1H-pyrrol-2-yl) vinyl]-pyridine. This weakening is due to the steric interaction of the two hydrogen bond donors. At the same time, more stringent steric conditions for forming the three-center interaction 2,5-bis [2-(pyridin-2-yl) vinyl]-1H-pyrrole lead to an actual breaking of one of the three-center hydrogen bond component involving increased preserved components. This makes the possibility of pendulum oscillation of the hydrogen bond in the latter case by alternately entering the hydrogen bond acceptors in the coordination sphere of the hydrogen atom.

A calculation scheme based on density functional theory with full geometry optimization, modified for structures with translational symmetry is applied to study the electron energy spectrum and magnetic characteristics of hexagonal gallium nitride and structures such as Y_xGa_{1– x}N (Y: donor (Ti) or acceptor (Zn) impurity). The dependence of relaxation shifts of interstitial atoms, the position of the chemical potential level, energy band boundaries, valence band widths, and energies corresponding to the intraband maxima of the density of states on the dopant concentration is discussed.

A quantum chemical and molecular dynamics simulation of a fragment of the sulfo cation exchanger in the form of glycine is performed. It is found that in the system studied an ionic pair dissociates.

The equilibrium geometries and vibrational frequencies of the ionic liquid 1-butyl-3-methylimidazolium cation and the alanine anion [BMIM][Ala] are studied using density functional theory (DFT) at the B3PW91/6-311+G(d,p) leve1. The most stable structures of the anion, the cation, and the ion pairs are obtained and characterized, and the geometry parameters of the ion pairs confirm the presence of a hydrogen bonding interaction between the anion and the cation. Natural bond orbital (NBO) analysis is also performed to analyze the atomic charge distribution and charge transfer in the [BMIM]⁺ cation and [BMIM][Ala] ionic liquids. The results show that there are the electrostatic interaction and multiple hydrogen bond interactions between the cation and the anion of the ionic liquids, and the stability of the ground state of the ion pairs mostly results from the hydrogen bonding between the lone pairs of O atoms in the anion and H in the imidazole cycle of the cation. There are some changes in microstructures and the charge distribution during the formation of the ion pairs.

A consistent calculation of frequencies and intensities of normal vibrations of some steroid phytohormones having biological activity (22S,23S)-24-epibrassinolide and (22S,23S)-28-homobrassinolide molecules) is performed within an original approach combining a classical normal mode vibration analysis by the molecular mechanics method and a quantum chemical estimation of absolute intensities. Based on a comparison of the experimental and theoretical spectral absorption curves the interpretation of IR spectral absorption bands is given for the first time and the effect of structural differences within the side chain of these molecules on the formation of their IR spectra in the range 1500-950 cm^–1 is estimated.

Potassium, rhubidium, and caesium fluorophosphatozirconates (hafnates) and oxo(hydroxo)fluorophosphatonitratometalates with PO₄^3-/Zr molar ratios of 2.0, 1.5, 1.0, 0.66, 0.5, and 0.33 are synthesized for the first time. Most of them form either fine crystalline or X-ray amorphous particles. In order to characterize them IR spectroscopy and SEM are used. For the crystalline compounds the types of PO₄ groups and the character of bonds between fluorine and water are revealed. The occurrence of triple МеF₄×Rb(PO₄)_0.33×RbNO₃ (Ме = Zr, Hf) salts and also M₃Me₃(PO₄)₅×3HF crystalline solvates is found. The layered habit of K₃Hf₃(PO₄)₅×3HF, RbHfF₂PO₄×0.5H₂O, Rb₃Hf₃(PO₄)₅×3HF, CsHfF₂PO₄×0.5H₂O, CsHf₂F₆PO₄×4H₂O, and CsH₂Hf₂F₂(PO₄)₃×2H₂O crystals gives grounds to suppose that the structure of these compounds is layered unlike the structure of triple МеF₄×Rb(PO₄)_0.33×RbNO₃ salts.

The heterobimetallic complexes [MMoO₂(L)(H₂O)₂] (where M = Zn²⁺ (1), Cu²⁺ (2), and Co²⁺ (4)) and [{MMoO₃(H₂L)(H₂O)₂}₂] (where M = Ni²⁺ (3) and Mn²⁺ (5)) are synthesized from bis(2-hydroxy-1-naphthaldehyde)malonoyldihydrazone (H₄L) using the monometallic precursor complex [MoO₂(H₂L)]×H₂O in ethanol. The composition of the complexes is established based on the data obtained from the elemental analysis and molecular weight determinations. The structure of the complexes is discussed in the light of data obtained from molar conductance, magnetic moment, electronic, EPR and IR spectroscopic studies.

New complexes of Co(II), Ni(II), and Cu(II) chlorides with 3-amino-4-ethoxycarbonylpyrazole (L) of the composition ML₂Cl₂ are synthesized. The compounds are studied by powder X-ray diffraction, electronic and IR spectroscopy, static magnetic susceptibility (temperature range 2-300 K). It is found that in the ML₂Cl₂ complexes (М = Co(II), Ni(II), Cu(II)) ferromagnetic exchange interactions between the unpaired electrons of metal ions occur. In [CoL₂Cl₂] and [NiL₂Cl₂] compounds a transition to the magnetically ordered state ( Т_с ≈ 10-12 K) is observed.

A spectroscopic method for the analysis of compounds belonging to methanofullerenes with different functionalization and a number of substituents is developed. In order to determine the composition of mixtures of these compounds the standard spectrophotometric procedure along with derivative spectroscopy are applied. Acceptable reproducubility and sensitivity of the methods used are demonstrated on model mixtures of fullerene derivatives. The reaction mass obtained in the interaction of fullerene with diallyl ester of malonic acid is analyzed.

Data on the solubility of argon in water and aqueous solutions of L and D enantiomers of α-valine and α-phenylalanine at T = 283-328 K and partial pressure of argon p₂ = 0.1 MPa are used to calculate the standard parameters of the Sechenov salt effect. Parameters of the solute–solute pair interaction are estimated within the formalism of the McMillan–Mayer theory. Evidence is provided for the presence of the chiral effect in the Sechenov parameters.

Using the simulation method for the diffraction patterns of one-dimensionally disordered materials, the effect of different violations in the layered structure of aluminum trihydroxides (gibbsite and bayerite) on their diffraction patterns is analyzed. The features of the diffraction patterns of a disordered gibbsite sample obtained by intercalation–deintercalation of lithium salts are considered.

For the first time, hybrid organic-inorganic 4-amino-1,2,4-triazolium fluorohafnate of the composition (C₂H₅N₄)[HfF₅(H₂O)₂]×H₂O is synthesized and its crystal structure is determined. The formation of a new type of a fluoride monomeric pentagonal bipyramid complex [HfF₅(H₂O)₂]^– anion with five F atoms and two H₂O molecules is revealed.

By X‑ray diffraction study the structure of two new carbonyl cluster complexes of the composition [Fe₄(μ₄-Q)(μ₄-AsMe)(CO)₁₁], where Q = Se or Te, is determined. The structures are molecular, and the selenium-containing cluster complex crystallizes in the form of a solvate with toluene.

By the interaction between (Et₄N)₂[Mo₂O₂S₈] and I₂ in DMF with a subsequent addition of 2,2'-bipyridine or 1,10-phenanthroline, new binuclear complexes [Mo₂O₂S₂I ₂(bipy)₂] (1) and [Mo₂O₂S₂I₂(phen)₂] (2) are obtained. The structure of [Mo₂O₂S₂I₂(bipy)₂] is determined using single crystal X‑ray diffraction. The compounds are characterized by elemental analysis and IR spectra. The [MoO(S₂)₂(bipy)] complex as a product of oxidative destruction of 1 is isolated and characterized.

Complex rhodium(III) salts of the composition cis-M[Rh(NH₃)₂(NO₂)₄]×n H₂O, where M = K⁺, Cs⁺, Ag⁺, (CH₃)₄N⁺, are synthesized and described. Their molecular and crystal structures are determined by single crystal X‑ray diffraction.

In this study four coordinated complexes of zinc(II) halides with a new symmetrical bidentate Schiff base ligand (2,5-MeO-ba)₂En are synthesized and characterized. The metal to ligand ratio of the complexes is found to be 1:1 with the formula of Zn((2,5-MeO-ba)₂En)X₂ (X = Cl (1), Br (2), I (3)). The crystal structure of the Schiff base ligand (2,5-MeO-ba)₂En is determined by X-ray crystallography from single crystal data. Also, the optimized geometries of the Schiff base ligand (2,5-MeO-ba)₂En and its zinc(II) complexes are calculated using the density functional theory method (B3LYP/6-31g). The obtained structural parameters of (2,5-MeO-ba)₂En are in agreement with the experimental data.

The Schiff base compounds N,N'-bis(3,4-dimethoxybenzylidene)-2,2-dimethylpropane-1,3-diamine hydrate, (3,4-MeO-ba) ₂Mepn.H₂O (1), and N,N'-bis(3,4-dimethoxybenzylidene)butane-1,4-diamine, (3,4-MeO-ba)₂bn (2), with different central groups derived from 3,4-dimethoxybenzaldehyde are synthesized and characterized by elemental analysis, FT—IR and ¹H NMR spectroscopy. The crystal structure of 1 is determined by single crystal X-ray diffraction. Each imino functional group (—C=N—) is coplanar with its adjacent benzene ring and the two benzene rings form a dihedral angle of 86.868(27)°. Title compound 1 crystallizes in the monoclinic space group P2₁/n with unit cell parameters: a = 9.0774(2) Å, b = 29.2138(5) Å, c = 8.5696(2) Å, b = 92.4756(14)°, V = 2270.41(8) ų and Z = 4.

Two 4-phenylbenzophenones (I) and (II) are synthesized via Friedel—Crafts reactions. There are four crystallographically independent molecules with different conformations in the crystal structure of [1,1'-biphenyl]-4-yl(2-chlorophenyl)methanone (I). Crystals are orthorhombic, Pca2₁, C₁₉H₁₃ClO, a = 13.699(3) Å, b = 8.9385(17) Å, c = 46.836(9) Å; V = 5735(2) ų, Z = 16, dx = 1.356 g/cm³. Torsion angles between the biphenyl rings are between 28.5° and 30.8°. Several C—H…O and C—H…Cl hydrogen bonds and weak π—π stacking contacts consolidate the crystal. Crystals of [1,1'-biphenyl]-4-yl(3-methoxyphenyl)methanone (II) are orthorhombic, Pbca, C₂₀H₁₆O₂, a = 7.8179(15) Å, b = 16.003(3) Å, c = 23.345(5) Å; V = 2920.7(10) ų, Z = 8, dx = 1.311 g/cm³. The torsion angle between the biphenyl rings is 28.1° and C—H…O hydrogen bonds are observed in compound (II).

The reaction of cadmium(II) chloride and 4-pyridine carboxylic acid (4-Hpyc) produces a new three-dimensional supramolecular compound [Cd(4-pyc)₂(H₂O)₄]_n (1). Compound 1 is characterized by IR spectroscopy and elemental analyses. The single crystal X-ray data show an infinite three-dimensional structure formed by the hydrogen bonding and π—π stacking interactions. The CdO nanoparticles are obtained by direct calcination at 400 °C, 500 °C and 600 °C in the air atmosphere as well as by thermolysis in oleic acid at 200 °C. The obtained cadmium(II) oxide nanoparticles are characterized by X-ray diffraction and scanning electron microscopy. This study demonstrates another potential application of cadmium(II) supramolecular compounds in the preparation of nanoscale cadmium(II) oxide materials with a specific size and morphologies.

A method to predict the vaporization enthalpies of aldehydes and ketones of different structures under normal conditions is proposed based on the modified Randič method.

Partial volumes V⁰ of amino acids in aqueous NH₄Cl and NaCl solutions are discussed. The salts have different effects on water structure. The contributions of the charged NH₃⁺ and COO^– groups of amino acids are found. Structural characteristics of hydrated complexes are calculated: partial volumes of water inside and outside the hydration sphere and hydration numbers. The same value of V⁰(NH₃⁺, COO^–) is achieved at a higher NH₄Cl concentration. The two salt systems with the same V⁰(NH₃⁺, COO^–) have similar values of the partial volumes of water and hydration numbers.

Bis(iso-maleonitriledithiolate)nickel(II) benzylpiperidinium, [BzPid]₂[Ni(i-mnt)₂] (1) is prepared and characterized by elemental analyses, UV, IR, molar conductivity, and single crystal X-ray diffraction. It is found that 1 crystallizes in the monoclinic space group P2₁/n with a = 9.551(1) Å, b = 16.520(2) Å, c = 11.004(1) Å, β = 96.60(1)°, V = 1724.6(3) ų, Z = 2. consolidate the stacking of the molecules The electrostatic interaction between [Ni(i-mnt)₂]^2– anions and [BzPid]⁺ cations consolidates the stacking of the molecules.

A new tetranuclear zinc(II) complex [Zn₄(tmphen)₄(tbip)₄(H₂O)₄] (1, tmphen = 3,4,7,8-tetramethyl-1,10-phenanthroline, H₂tbip = 5- tert-butyl isophthalic acid) is hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction, elemental analysis, and IR spectroscopy. In complex 1, four tbip^2– ligands act as bridges between four neighboring Zn atoms to form an unusual tetranuclear zinc cluster. The clusters are further connected by two types of O—H⋯O and C—H⋯O hydrogen bonds, generating a three-dimensional supramolecular structure. Meanwhile, π—π stacking interactions and C—H⋯p interactions further consolidate the three-dimensional supramolecular framework of 1. In addition, the luminescence measurements reveal that complex 1 exhibits strong fluorescent emissions in the solid state at room temperature.

A cadmium(II) complex dicyanidobis(N,N'-dimethylthiourea- S) cadmium(II) [Cd(Dmtu)₂(CN)₂] (1) is prepared and its structure in the solid state is determined by single crystal X-ray structural analysis. The cadmium(II) ion is four-coordinate having a distorted tetrahedral geometry composed of two cyanide C atoms and two thione S atoms of N,N'-dimethylthiourea (dmtu). The molecular structure is stabilized by intermolecular N—H⋯N(CN) hydrogen bonding interactions that lead to a 3D network structure. The complex was also characterized by IR and NMR spectroscopy.

Single-crystal X-ray diffraction is used to determine the structure of a new compound based on an octahedral cyanide anionic cluster complex of rhenium and a trimethyltin(IV) cation: {(SnMe₃)₃[Re₆Se₈(CN)₆]} (1). The crystallographic characteristics: space group С2/с, a = 13.9898(14) Å, b =15.334(2) Å, c = 20.761(2) Å, β = 97.75(0)°, V = 4412.91(90) ų, Z = 4, d_x = 3.607 g/cm³, and R = 0.0526. The compound has a framework structure; two porous frameworks with pcu topology interpenetrate each other.

An X-ray crystallographic study is conducted of single crystals with the composition [Ba₂(Aet^–)₂×10(H₂O)]²⁺×2(Aet^–)×4H₂O, where Aet^– = (C₁₀H₁₁N₄O₂S₂)^– is the ethazole (2-( para-aminobenzenesulfamido)-5-ethyl-1,3,4-tiadiazole) anion. The crystals are monoclinic; the space group is P2₁/c, Z = 2; а = 9.793(2) Å, b = 15.408(4) Å, and c = 22.553(6) Å; β = 94.98(2)°; and R = 0.047. The independent part of the compound’s structural formula, [Ba(Aet)(OH₂)₅](Aet)×2H₂O, is isostructural with the analogous compound with the Sr atom. The ethazole anion is coordinated to the complexing metal atom by oxygen and nitrogen atoms to form a four-membered ring.

The crystal structure of [2-(2-hydroxybenzilydene)hydrazinecarboxoamidato(1-)][2-(2-hydroxy-benzilydene)hydrazinecarboxoamidato(2-)]chromium monohydrate [Cr(HL)(L)]×H₂O (I), where H₂L is salicylaldehyde semicarbazone, is determined. In I the central chromium atom is octahedrally surrounded by two ligand anions in the mer position and coordinated azomethine nitrogen atoms, phenol and carbamide oxygen atoms. In both ligands phenol groups are deprotonated; in one of them the imine group is also deprotonated. In the crystal, complexes of the compound studied are hydrogen bonded into layers along the [100] direction, with π–π stacking being observed between the phenyl rings inside the layer along with the X–Н⋯Cg (π ring) interaction.

Two hydrazone compounds N'-(2,4-dichlorobenzylidene)-4-methylbenzohydrazide monohydrate (1) and 2-chloro-5-nitro- N'-(4-methylbenzylidene)benzohydrazide (2) derived from 4-methylbenzohydrazide with different benzaldehydes are synthesized and characterized by physicochemical methods and single crystal X-ray diffraction. Compound 1 crystallizes in the orthorhombic space group P2₁2₁2₁ with unit cell parameters a = 4.714(2) Å, b = 13.093(3) Å, c = 24.754(3) Å, V = 1527.9(8) ų, Z = 4, R ₁ = 0.0812, and wR ₂ = 0.1623. Compound 2 crystallizes in the monoclinic space group Cc with unit cell parameters a = 11.564(2) Å, b = 13.271(2) Å, c = 9.462(2) Å, β = 96.860(2)°, V = 1441.7(4) ų, Z = 4, R₁ = 0.0461, and wR₂ = 0.0896. The crystals of the compounds are stabilized by intermolecular hydrogen bonds as well as π⋯π stacking interactions.