Structure and some properties of [UO<Subscript>2</Subscript>CrO<Subscript>4</Subscript>{CH<Subscript>3</Subscript>CON(CH<Subscript>3</Subscript>)<Subscript>2</Subscript>}<Subscript>2</Subscript>]

A new complex [UO₂CrO₄{CH₃CON(CH₃)₂}₂] (I) was studied by thermal analysis, IR spectroscopy, and X-ray crystallography. The crystals are monoclinic: a = 13.8108(11) Å, b = 8.6804(7) Å, c = 13.0989(10) Å, β = 104.777(1)°, V = 1518.4(2) ų, space group P2₁/c, Z = 4, R = 2.39%. The structure of I contains infinite chains of the [UO₂CrO₄{CH₃CON(CH₃)₂}₂] composition running along [001]; the complex belongs to the AT¹¹M¹ ₂ crystal-chemical group (A = UO ₂ ²⁺ , T¹¹ = CrO ₄ ^2? , M¹ = CH₃CON(CH₃)₂) of uranyl complexes. The chains are linked into a three-dimensional framework due to hydrogen bonds between oxygen atoms of chromate ions and hydrogen atoms of methyl groups of the dimethylacetamide.     

Crystal Structure of [UO<Subscript>2</Subscript>SO<Subscript>4</Subscript>{(CH<Subscript>3</Subscript>)HNCONH(CH<Subscript>3</Subscript>)}<Subscript>2</Subscript>]

The single crystals of [UO₂SO₄{(CH₃)HNCONH(CH₃)}₂] (I) were synthesized and studied by X-ray diffraction. The crystals are monoclinic, a = 6.847(1) Å, b = 14.259(3) Å, c = 14.297(3) Å, β = 93.451(4)°, space group P2₁/n, Z = 4. The main structural units of crystals I are ribbons whose composition coincides with the composition of the compound. The crystal chemical formula of the complex is AT³M ₂ ¹ (A = UO ₂ ²⁺ ).     

Synthesis and structure of [UO<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>){CONH<Subscript>2</Subscript>N(CH<Subscript>3</Subscript>)<Subscript>2</Subscript>}<Subscript>2</Subscript>]

The single crystals of [UO₂(C₂O₄){CONH₂N(CH₃)₂}₂] were synthesized and studied by X-ray diffraction. The crystals are monoclinic, a = 7.461(2) Å, b = 8.828(2) Å, c = 11.756(2) Å, β = 107.21(3)°, space group Pc, Z = 2, R = 2.94%. The structure comprises infinite chains [UO₂(C₂O₄){CONH₂N(CH₃)₂}₂] extended along [001] and corresponding to the AT¹¹M ₂ ¹ crystallochemical group (A = UO ₂ ²⁺ , T¹¹ = C₂O ₄ ^2? , M¹ = N,N-CONH₂N(CH₃)₂) of uranyl complexes. The chains are connected into a three-dimensional framework by hydrogen bonds involving the oxygen atoms of oxalate and uranyl ions and the N,N-dimethylcarbamide methyl groups.     

Competition between H<Subscript>2</Subscript>O and CH<Subscript>3</Subscript>OH molecules in the formation of the simplest stable proton disolvates and their solvation in aqueous methanol solutions of KOH and CH<Subscript>3</Subscript>OK

IR spectroscopic and quantum chemical methods are used to study the competition between water and methanol molecules in the formation of the simplest stable proton disolvates and their subsequent solvation in the case of solutions of KOH in CH₃OH and CH₃OK in H₂O with similar stoichiometries (~1:3-3.5). The complexes found in these solutions are analysed to determine their composition and structure: they are found to be heteroions (CH₃O?H?OH)^– solvated by two similar solvent molecules. In both cases, there are virtually no complexes of the second possible type (CH₃OH·(CH₃O?H?OCH₃)^–··H₂O or CH₃OH·(HO?H?OH)^–·H₂O), which appears to be due to the stoichiometric compositions of the solutions. It is shown that a DFT calculation (B3LYP/6-31++G(d,p)) of linear complexes with strong (~15-30 kcal/mol) H bonds reproduces, with good accuracy, the IR spectra of the solutions, which consist mainly of these complexes.     

A quantum-chemical study of the thermodynamic properties of the CNOH<Subscript>3</Subscript> isomers

The B3LYP/6-311++G(3df,3pd) DFT method was used to determine the geometry and vibrational frequencies for the formamide, formaldoxime, nitrosomethane, oxaziridine, and formimide. The potential energy functions of the hindered internal rotations were calculated. The conformers of formaldoxime and formimide were determined. For all the molecules, including the conformers, the thermodynamic characteristics Δ_f H° (298 K), S°(298 K), C _p(298 K), and Δ_f G° (298 K) were determined. The temperature dependences C _p(T) within 298–1500 K were represented in the form of cubic polynomials.     

Study of the structural and thermodynamic stability of pentacoordinated nitrogen compounds NF<Subscript>2</Subscript>X<Subscript>3</Subscript> (X = H,Cl, Br): <Emphasis Type="Italic">Ab initio</Emphasis> calculations

Quantum chemical calculations of compounds with a pentacoordinated nitrogen atom such as NF₂H₃ (in the CCSD(Full)/6-311++G(d,p) approximation), NF₂Cl₃ and NF₂Br₃ (in the B3LYP/6-311+G(d) approximation) are carried out. It is found that NF₂Cl₃ and NF₂Br₃ molecules are structurally stable, but thermodynamically unstable, and are isomerized to NFCl₂...FCl and NFBr₂...FBr molecular complexes respectively. The total energy of NFCl₂...FCl and NFBr₂...FBr complexes is lower than the total energy of NF₂Cl₃ and NF₂Br₃ molecules by 62 kcal/mol and 64 kcal/mol respectively. The trigonal bipyramidal form of the NF₂H₃ molecule of D _3h symmetry is structurally unstable: a first-order saddle point corresponds to it on the potential energy surface of the system. A second-order saddle point is found on the reaction path of NF₂H₃ isomerization.     

Structural and electronic properties of heptachlor

In this work, the molecular geometry of heptachlor is investigated using ab initio HF, DFT, LDA, and GGA methods. The natural bond orbital (NBO) analysis is performed at the B3LYP/6-311++G(d,p) level of theory. The first order hyperpolarizability β_total, the mean polarizability Δα, the anisotropy of the polarizability Δα, and the dipole moment μ, are calculated by B3LYP/6-311++G(d,p) and HF/6- 311++G(d,p) methods. The first order hyperpolarizability (β_total) is calculated based on the finite field approach. UV spectral parameters along with HOMO, LUMO energies for heptachlor are determined in vacuum and the solvent phase using HF, DFT, and TD-DFT/B3LYP methods implemented with the 6-311++G(d,p) basis set. Atomic charges and electron density of heptachlor in vacuum and ethanol are calculated using DFT/B3LYP and TD-DFT/B3LYP methods and the 6-311++G(d,p) basis set. In addition, after the frontier molecular orbitals (FMOs), the molecular electrostatic potential (MEP), the electrostatic potential (ESP), the electron density (ED), and the solvent accessible surface of heptachlor are visualized as a results of the B3LYP/6-311++G(d,p) calculation. Densities of states (DOS), the external electric field (EF) effect on the HOMO-LUMO gap, and the dipole moment are investigated by LDA and GGA methods.     

Structural investigation of [Au(en)<Subscript>2</Subscript>]Cl(ReO<Subscript>4</Subscript>)<Subscript>2</Subscript> and [Au(en)<Subscript>2</Subscript>](ReO<Subscript>4</Subscript>)<Subscript>3</Subscript> complexes

Novel complex salts [Au(en)₂]Cl(ReO₄)₂ (I) and [Au(en)₂](ReO₄)₃ (II), en = ethylenediamine, are obtained. Their crystal structures are determined by single crystal X-ray diffraction. Complex I crystallizes in the triclinic crystal system: a = 6.2172(7) Å, b = 7.1644(8) Å, c = 8.8829(8) Å, α = 96.605(4)°, β = 110.000(4)°, γ = 97.802(4)°, P-1 space group, Z = 1, d _x = 3.905 g/cm³; complex II crystallizes in the monoclinic crystal system: a = 15.244(2) Å, b = 7.6809(8) Å, c = 9.3476(12) Å, β = 127.004(3)°, C2 space group, Z = 4, d _x = 4.057 g/cm³.     

Synthesis and X-ray investigation of Rb<Subscript>2</Subscript>[Pd(NO<Subscript>3</Subscript>)<Subscript>4</Subscript>] and Cs<Subscript>2</Subscript>[Pd(NO<Subscript>3</Subscript>)<Subscript>4</Subscript>]

Powder and single crystal X-ray diffraction studies have been performed for anhydrous nitrate complexes Rb₂[Pd(NO₃)₄] (I) and Cs₂[Pd(NO₃)₄] (II). Crystal data for I: a = 7.843(1) Å, b = 7.970(1) Å, c = 9.725(1) Å; β = 100.39(1)°, V = 597.9(1) Å ³, space group P2₁/c, Z = 2, d _calc = 2.918 g/cm³; for II: a = 10.309(2) Å, b = 10.426(2) Å, c = 11.839(2) Å; β = 108.17(3)°, V = 1209.0(4) ų, space group P2₁/c, Z = 4, d ^calc = 3.408 g/cm³. The structures are formed by isolated [Pd(NO₃)₄]^2? complex anions and alkali metal cations. The plane-square environment of the Pd atom is formed from the oxygen atoms of the monodentate nitrate groups. The geometrical characteristics of the complex anions are analyzed. Compound II has a short contact Pd...Cs 3.252 Å.     

Crystal structure of KPb<Subscript>2</Subscript>Cl<Subscript>5</Subscript> and KPb<Subscript>2</Subscript>Br<Subscript>5</Subscript>

The KPb₂Cl₅ and KPb₂Br₅ crystals are monoclinic (P2₁/c) with a microtwinned structure. X-ray analysis of chloride resulted in the parameters a = 8.854(2) Å, b = 7.927(2) Å, c = 12.485(3) Å; β = 90.05(3)°, d_calc = 4.78(1) g/cm³ (STOE STADI4, MoK_α, 2θ_max = 80°), R₁ = 0.0702 for 4094 F ≥ 4 σ(F) reflections. For bromide, a = 9.256(2) Å, b = 8.365(2) Å, c = 13.025(3) Å; β = 90.00(3)°, d_calc = 5.62(1) g/cm³ (Bruker P4, MoK_α, 2θ_max = 70°), R₁ = 0.0692 for 3076 F ≥ 4 (F) reflections.     

Hydrolysis of coordinated aminoacetonitrile in a platinum(IV) complex. Crystal structure of [PtPy(NH<Subscript>2</Subscript>CH<Subscript>2</Subscript>COO)Cl<Subscript>3</Subscript>]

Heating of a hydrochloric acid solution of trans-PtPy(NH₂CH₂CN)Cl₄ results in the hydrolysis of coordinated aminoacetonitrile to aminoacetic acid with the formation of a five-membered chelate ring attached to platinum through the nitrogen atom of the amino group and the oxygen atom of the carboxy group. X-ray diffraction analysis of [PtPy(NH₂CH₂COO)Cl₃] is carried out. The crystals are monoclinic: space group C2/c, a = 21.704(2), b = 8.7027(7), c = 15.576(1) Å, β = 126.606(1)^o, V = 2361.8(3) ų, Z = 8; R _hkl = 0.057, wR = 0.141. In the neutral complex, the Pt atom has a distorted octahedral coordination. The equatorial plane is formed by a Cl atom (Pt-Cl, 2.284(3) Å), the N atom of the Py molecule (Pt-N, 2.062(8) Å), and the N and O atoms of the bidentate-chelating ligand (Pt-N, 2.039(8); Pt-O, 2.026(7) Å); two Cl atoms are arranged in the apical positions (Pt-Cl, 2.301(3) and 2.312(3) Å). The five-membered chelate ring has a flattened gauche conformation with an NCCO torsion angle of 19(1)°.     

Organic-inorganic hybrid perovskite (C<Subscript>6</Subscript>H<Subscript>5</Subscript>(CH<Subscript>2</Subscript>)<Subscript>2</Subscript>NH<Subscript>3</Subscript>)<Subscript>2</Subscript>CdCl<Subscript>4</Subscript>: Synthesis,structural and thermal properties

The present research work reports the study on crystal structure, vibrational spectroscopy and thermal analysis of organic-inorganic hybrid compound (C₆H₅(CH₂)₂NH₃)₂CdCl₄. Single crystals of bis(phenethylammonium)tetrachlorocadmate (C₆H₅(CH₂)₂NH₃)₂CdCl₄ (PEA–Cd) were obtained by diffusion at room temperature. This compound crystallizes in the orthorhombic space group C2cb with unit cell parameters a = 7.4444(2) Å, b = 38.8965(3) Å, c = 7.3737(2) Å and Z = 4. Single crystal structure has been solved and refined to R = 0.036 and wR = 0.092. The structure consists of an extended [CdCl₄]^2– network and two [C₆H₅(CH₂)₂NH₃]⁺ cations to form a two-dimensional perovskite system. The infrared (IR) spectrum of the title compound was recorded at room temperature. Differential scanning calorimetry (DSC) was used to investigate the phase transition; this compound exhibits a reversible single solid-solid phase transition.     

A quantum-chemical study of the interaction of the HeT<Superscript>+</Superscript> ion with cycloalkanes and their oxidation products

The RHF/6-311G*(3d), RHF/6-311++G**(3df, 3p) and MP2/6-311G*(3d) ab initio methods were used to calculate the equilibrium structure of the products of the ion-molecular reaction of tritium ion transfer from HeT⁺ to cyclopentane and cyclohexane. Similar reactions with cyclopentanol and cyclopentanone were calculated at the RHF/6-311G*(3d) level. The interaction of HeT⁺ with cycloalkanes was found to produce onium ions with cyclic structures, in which the tritium atom held neighboring methylene groups together. With the alcohol and ketone, not only cyclic but also stabler linear cations could be formed, and the addition of the tritium ion directly to the oxygen atom was possible. The suggestion was made that the chain of tritium ion transfer reactions was the mechanism of the accumulation of tritium by hydrocarbon oxidation products when T₂ was dissolved in mineral oils.     

Nitrosonium nitrite isomer of N<Subscript>2</Subscript>O<Subscript>3</Subscript>: Quantum-chemical data

The geometrical, electronic, and thermodynamic parameters of three known isomers of dinitrogen trioxide N₂O₃ were calculated by the density functional theory DFT/B3LYP method using the 6-311++G(3df) basis. The structure of the new isomer, NONO₂, was calculated. From the calculation of vibrational frequencies it follows that the structure of NONO₂ has a local potential energy minimum and corresponds to the stationary state of the N₂O₃ isomer. The molecular structure of NONO₂ is characterized by a substantial negative charge on the NO₂ fragment and positive charge on the NO fragment. The electronic structure of the NO⁺NO ₂ ^? isomer can be characterized as nitrosonium nitrite, which can be oxidized to nitrite and participate in nitrosylation in accordance with the biogenic characteristics of the NO _x intermediate, assumed to be formed in biological systems during the oxidation of NO.     

Synthesis and crystal structures of Schiff base oxovanadium(V) complexes [VO(Bhm)(OCH<Subscript>3</Subscript>)(CH<Subscript>3</Subscript>OH)] and [VO<Subscript>2</Subscript>(Bpp)]

Compound [VO(acac)₂] reacts with the Schiff bases N′-(5-bromo-2-hydroxybenzylidene)-2-hydroxy-3-methylbenzohydrazide (H₂Bhm) and 4-bromo-2-[(2-piperidin-1-ylethylimino)methyl]phenol (HBpp) in absolute methanol to give the oxovanadium(V) complexes [VO(Bhm)(OCH₃)(CH₃OH)] (I) and [VO₂(Bpp)] (II), respectively. Both complexes were characterized by elemental analysis, IR spectra, and single-crystal X-ray determination. The crystal of I crystallizes in the triclinic space group \(P\bar 1\) with a = 7.625(2), b = 11.240(3), c = 12.156(4) Å, α = 77.404(5)°, β = 75.770(4)°, γ = 79.922(5)°, V = 977.4(5) ų, Z = 2. The crystal of II crystallizes in the monoclinic space group P2/c with a = 26.760(3), b = 6.655(1), c = 17.570(2) Å, β = 100.335(2)°, V = 3078.2(7) ų, Z = 8. The V atom in I is in an octahedral coordination, and those in II are intervenient between square pyramidal and trigonal bipyramidal coordination.     

Crystal structures of [Zn(SALIMP)(CH<Subscript>3</Subscript>CO<Subscript>2</Subscript>)]<Subscript>2</Subscript> and [Cu(SALIMP)Cl] with 2-[[(2-pyridinylmethyl) imino]methyl]phenol (HSALIMP) as a ligand

Two complexes [Zn(SALIMP)(CH₃CO₂)]₂ (1) and [Cu(SALIMP)Cl] (2) are obtained by the reactions of zinc(II) and copper(II) salts with a tridentate Schiff base ligand 2-[[(2-pyridinylmethyl) imino]methyl]phenol (HSALIMP). Their structure is determined by single crystal X-ray diffraction. Data for complex 1: C₃₀H₂₈N₄O₆Zn₂, CCDC number: 668213, M _r = 671.3, monoclinic, C2/c, with a = 34.670(5) Å, b = 15.266(2) Å, c = 23.464(4) Å, β = 114.045(2)°, V = 11341(3) ų, Z = 16, F(000) = 5504, GOOF(F ²) = 0.894, the final R = 0.0520 and wR = 0.1272 for 10515 observed reflections with I > 2σ(I); complex 2: C₁₃H₁₂N₂OClCu, CCDC number: 668211, M _r = 311.24, triclinic, P-1, with a = 7.4050(8) Å, b = 10.2369(11) Å, c = 16.2873(17) Å, α = 87.728(2)°, β = 87.818(2)°, γ = 78.279(2)°, V = 1207.4(2) ų, Z = 4, F(000) = 632, GOOF(F ²) = 1.077, the final R = 0.0326 and wR = 0.0381 for 4209 observed reflections with I > 2σ(I).     

X-ray diffraction study of CsZn<Subscript>2</Subscript>Br<Subscript>5</Subscript>

CsZn₂Br₅ crystals are studied by X-ray diffraction. The compound crystallizes in the monoclinic system with the unit cell parameters a = 6.8880(12) Å, b = 10.4703(19) Å, c = 6.5197(9) Å, β = 108.25°, V = 446.55 ų, ρ_calcd = 4.960 g/cm³. Refractive indices are n _p = 1.640 and n _p = 1.754.     

Resonant photoemission and absorption spectroscopy study of the Cu<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>TiSe<Subscript>2</Subscript> electronic structure

The Cu3p and Cu2p resonance photoelectron spectra of the valence bands and core levels as well as Ti and CuL _2,3 absorption spectra for monocrystals 1T-Cu _x TiSe₂ were studied. The valence spectra obtained at Cu3p and Cu2p resonance drastically differ from each other. For Cu 3p-3d resonance, there are several bands corresponding to different channels of excited state decay. Spectra of the valence bands at Cu 2p-3d resonance are virtually identical to the spectra of pure TiSe₂. As follows from the absorption spectra, titanium atoms have the oxidation state 4+, whereas copper atoms are close to the free ion state.     

A Quantum Chemical Study of C<Subscript>60</Subscript>Cl<Subscript>30</Subscript>, C<Subscript>60</Subscript>(OH)<Subscript>30</Subscript> Molecules and Fe@C<Subscript>60</Subscript>(OH)<Subscript>30</Subscript> Endocomplex

(U)PBE0/cc-pVDZ method is used to study the structure of C₆₀Cl₃₀, C₆₀(OH)₃₀ molecules and Fe@C₆₀(OH)₃₀ endocomplex. The triplet state of the endocomplex is shown to be the lowest in energy among its four states corresponding to different spin multiplicities and positions of Fe nucleus within the fullerene cavity. This state is characterized by bonding between the iron atom and one of two benzenoid cycles of the carbon cage, six internuclear Fe–C distances (208 pm), and 1s²2s²2p⁶3s²3p⁶3d^7.24s^0.14p^0.3 electron configuration of iron with spin population of 2.36.     

Crystal structures of <Emphasis Type="Italic">trans</Emphasis>-[Re<Subscript>6</Subscript>S<Subscript>8</Subscript>(CN)<Subscript>2</Subscript>L<Subscript>4</Subscript>] complexes,L = pyridine or 4-methylpyridine

The structures of three novel octahedral rhenium cluster compounds [Re₆S₈(CN)₂(py)₄]·H₂O (1), [Re₆S₈(CN)₂(4-Mepy)₄] (2), [Re₆S₈(CN)₂(4-Mepy)₄]·4-Mepy (3) (py = pyridine, 4-Mepy = 4-methylpyridine) are determined by X-ray crystallography. Crystal data are: C2/m space group, a = 14.813(1) Å, b = 14.772(1) Å, c = 9.2122(6) Å, β = 119.085(2)°, V = 1761.7(2) ų, d _x = 3.318 g/cm³, R = 0.0585 (1); I4₁/amd space group, a = 16.0018(3) Å, c = 14.7186(5) Å, V = 3768.81(16) ų, d _x = 3.169 g/cm³, R = 0.0489 (2); P2₁/c space group, a = 9.0452(4) Å, b = 15.8065(7) Å, c = 15.2951(6) Å, β = 103.700(2)°, V = 2124.57(16) ų, d _x = 2.957 g/cm³, R = 0.0245 (3). Molecular cluster complexes interact via π-π stacking affording 3D frameworks in 1 and 2 and chains in 3.