Kinetics of reactions between arylnitroso oxides and methyl vinyl ketone

The kinetics of the reactions of phenylnitroso oxide, (4-methylphenyl)nitroso oxide, (4-methoxyphenyl) nitroso oxide, 4-(N, N -dimethylamino)phenylnitroso oxide, (4-chlorophenyl)nitroso oxide, (4-bromophenyl) nitroso oxide, and (4-nitropenyl)nitroso oxide with methyl vinyl ketone in acetonitrile at 295 K was studied. With the use of 4-CH₃O-C₆H₄-NOO as an example, it was found that only the trans isomers of nitroso oxides entered into the reaction. The rate constants of the reactions of the trans isomers of nitroso oxides with methyl vinyl ketone were measured. A linear correlation between the logarithms of reaction rate constants and the electronic properties of substituents in the aromatic rings of nitroso oxides on the Hammett scale was established: ρ = 1.11 ± 0.08; r = 0.990.     

Structure of arsenic 8-mercaptoquinolinate: Synthesis and crystal structure of arsenic 4-methoxy-8-mercaptoquinolinate As[C<Subscript>9</Subscript>H<Subscript>5</Subscript>(OCH<Subscript>3</Subscript>)NS]<Subscript>3</Subscript>

Arsenic 4-methoxy-8-mercaptoquinolinate As[C₉H₅(4-OCH₃)NS]₃ (I) was synthesized and studied by X-ray diffraction. Crystals are trigonal: space group R3, a = b = 13.9867(4) Å, c = 12.4991(5) Å, γ = 120°, V = 2117.58(12) ų, ρ = 1.519 g/cm³, Z = 3. An arsenic atom in the crystal structure occupies a special position on axis 3. The structural unit of the crystal (neutral complex I) has symmetry C3. 4-Methoxy-8-mercaptoquinoline acts as a bidentate (N,S-) ligand. The coordination polyhedron of the arsenic atom is a symmetric octahedron (3S + 3N) or, with allowance for the lone electron pair, ψ-one-capped octahedron (3S + 3N + E). Bond lengths are as follows: As-S, 2.3179(7)Å; As…N 2.688(3) Å. The geometries of coordination polyhedra of arsenic atoms are compared in the crystal structures of As(C₉H₆NS)₃, As[C₉H₅(2-CH₃)NS]₃, and As[C₉H₅(4-CH₃)NS]₃.     

Structure and energetics of β-diketonates. XVI. Molecular structure and vibrational spectrum of zinc acetylacetonate according to gas-phase electron diffraction and quantum-chemical calculations

The molecular structure of zinc acetylacetonate was studied in a simultaneous electron diffraction and mass spectrometric experiment at 376(7) K and by quantum-chemical calculations. The Zn(acac)₂ molecule has a structure of D _2d symmetry with the chelate rings lying in mutually perpendicular planes. The main geometrical parameters of the molecule are r _h1(Zn-O) = 1.942(4) Å, r _h1(C-O) = 1.279(3) Å, r _h1(C-C_r) = 1.398(3) Å, r _h1(C-C _m ) = 1.504(5) Å, ∠(O-Zn-O) = 93.2(7)°, ∠(Zn-O-C) = 125.9(7)°, ∠(C-C_r-C) = 125.8(14)°, ∠(O-C-C _m ) = 115.2(9)°. The effective rotation angle of methyl groups is close to 30°, which is indicative of the free rotation of these groups. The vibration frequencies were obtained by quantumchemical calculations, and the IR spectrum of the Zn(acac)₂ molecule was interpreted.     

Structure and thermal properties of volatile copper(II) complexes with β-diimine derivatives of acetylacetone and the structure of 2-(methylamino)-4-(methylimino)-pentene-2 crystals

Copper(II) chelates with β-diimine derivatives of acetylacetone that have a general formula of Cu(R¹C(NR²)CHC(NR²)R¹)₂, where R¹, R² are alkyl substituents, are synthesized. The complexes were identified using elemental analysis, melting point measurements, and high-temperature mass spectrometry data. Knudsen technique is employed to determine the vapor pressure temperature dependence, and standard thermodynamic parameters of sublimation ΔH _T ⁰ and ΔS _T ⁰ are derived. A single crystal X-ray diffraction study is carried out for copper(II) complexes of Cu(CH₃-C(NCH₃)-CH-C(NCH³)-CH₃)₂ (a = 10.363(1) Å, b = 11.978(1) Å, c = 12.653(1) Å, V = 1570.6(3) ų, space group Pnc2, Z = 4, d _calc = 1.328 g/cm³, R = 0.027), Cu(CH₃-C(NC₂H₅)-CH-C(NC₂H₅)-CH₃)₂ (a = 11.782(4) Å, b = 13.951(8) Å, c = 25.591(8) Å, V = 4206(3) ų, space group C222¹, Z = 8, d _calc = 1.169 g/cm³, R = 0.10), and also 2-(methylamino)-4-(methylimino)-pentene-2 CH₃-(C=(NCH₃))-CH=(C-(NHCH₃))-CH₃ (a = 12.129(2) Å, b = 12.034(2) Å, c = 5.692(1) Å, β = 107.05(3)°, V = 794.3(3) ų, space group Cc, Z = 4, d _calc = 1.055 g/cm³, R = 0.06). Van der Waals lattice energy E _cryst is calculated for the cooper(II) complexes by the atom-atom potential technique. The calculated values are compared to experimental sublimation enthalpies Δ H _T ⁰ .     

Syntheses and structures of six-coordinate K[Ga<Superscript>III</Superscript>(Cydta)] · 2H<Subscript>2</Subscript>O and K[Ga<Superscript>III</Superscript>(Pdta)] · 3H<Subscript>2</Subscript>O complexes

The title complexes, K[Ga^III(Cydta)] · 2H₂O(Cydta = trans-1,2-cyclohexanediaminetetraacetic acid) and K[Ga^III(Pdta)] · 3H₂O (Pdta = propylenediaminetetraacetic acid), were prepared, and their structures were studied by IR spectra, elemental analyses, NMR spectra, and single-crystal X-ray diffraction techniques. In the K[Ga^III(Cydta)] · 2H₂O complex, the Ga³⁺ is six-coordinated by the Cydta ligand yielding an octahedral conformation, and the complex crystallizes in the monoclinic system with the P2₁/c space group. The crystal data are as follows: a = 16.5039(19), b = 13.1499(16), c = 8.5204(10) Å, β = 101.650(2)°, V = 1811.0(4) ų, Z = 4, ρ = 1.757 g/cm³, μ = 1.805 mm^?1, F(000) = 984, R = 0.0291, and wR = 0.0698 for 3713 observed reflections with I ≥ 2σ(I). In the K[Ga^III(Pdta)] · 3H₂O complex, the Ga³⁺ is also six-coordinated by the Pdta ligand yielding an almost standard octahedral conformation, and the complex crystallizes in the orthorhombic system with P2₁2₁2₁ space group. The crystal data are as follows: a = 8.8913(10), b = 11.6181(13), c = 17.0227(19) Å, V = 1758.4(3) ų, Z = 4, ρ = 1.757 g/cm³, μ = 1.862 mm^?1, F(000) = 952, R = 0.0288, and wR = 0.0724 for 3556 observed reflections with I ≥ 2σ(I).     

Gas electron diffraction and quantum chemical study of the structure of a 2-nitrobenzenesulfonyl chloride molecule

A combined gas electron diffraction and quantum chemical (B3LYP/6-311+G**, B3LYP/cc-pVTZ, B3LYP/cc-pVTZ, midix (Cl), and MP2/cc-pVTZ) study of the structure of a 2-NO₂-C₆H₄-SO₂Cl molecule is performed. It is found experimentally that at a temperature of 345(5) K the gas phase contains two conformers of the C ₁ symmetry. Conformer I with a nearly perpendicular arrangement of the S-Cl bond with respect to the benzene ring plane (the C(NO₂)-C-S-Cl torsion angle is 84(3)°) is contained predominantly (69(12)%). In conformer II, the S-Cl bond is located near the benzene ring plane (the C(NO₂)-C-S-Cl angle is 172(3)°). The following experimental internuclear distances (Å) are obtained for conformer I: r _h1(C-H) = 1.064(15), r _h1(C-C)_av = 1.397(3), r _h1(C-S) = 1.761(6), r _h1(S-O)_av = 1.426(4), r _h1(S-Cl) = 2.043(5), r _h1(N-O)_av = 1.222(4), r _h1(C-N) = 1.485(16). In both conformers, the NO₂ group is turned by more than 30° relative to the benzene ring plane.     

Synthesis and crystal structure of hydrogen strontium paratungstate Sr<Subscript>4.5</Subscript>H[W<Subscript>12</Subscript>O<Subscript>40</Subscript>(OH)<Subscript>2</Subscript>] · 30H<Subscript>2</Subscript>O

The conditions for formation of individual isopolytungstates in solutions of the Sr(NO₃)₂-Na₂WO₄-HNO₃-H₂O system acidified to Z = ν(H⁺)/ν(WO ₄ ^2? ) = 1.29 were studied. The conditions of formation of strontium paratungstate B, strontium hydroheptatungstate, and hydrogen strontium paratungstate were determined. An X-ray diffraction study of single crystals of Sr_4.5H[W₁₂O₄₀(OH)₂] · 30H₂O was carried out. Selected crystallographic data for H₆₃O₇₂Sr_4.50W₁₂ are: M _r = 3815.99, monoclinic, space group P2₁/c, a = 11.41270(10) Å, b = 23.7575(3) Å, c = 12.4392(2) Å, β = 110.476(2)°, V = 3159.64(7) ų at T = 293 K, Z = 2, ρ = 4.011 g/cm³, F₀₀₀ = 3396, μ(MoK _α) = 25.635 mm^?1, ?14 ≤ h ≤ 14, ?30 ≤ k ≤ 30, ?16 ≤ l ≤ 16, R _F = 0.0430, wR ² = 0.1067 (R _F = 0.0506, wR ² = 0.1129), and S = 1.043.     

Crystal structures of a family of layered coordination polymers containing divalent metal ions (Mn<Superscript>2+</Superscript>, Co<Superscript>2+</Superscript>, Ni<Superscript>2+</Superscript> and Zn<Superscript>2+</Superscript>) and the 3-amino 4-methyl benzoate ion

The syntheses and crystal structures of the layered coordination polymers M(C₈H₈NO₂)₂ [M = Mn (1), Co (2), Ni (3) and Zn (4)] are described. These isostructural compounds contain centrosymmetric trans-MN₂O₄ octahedra as parts of infinite sheets; the ligand bonds to three adjacent metal ions in μ³-N,O,O′ mode from both its carboxylate O atoms and its amine N atom. In each case, weak intra-sheet N–H?O and C–H?O hydrogen bonds may help to consolidate the structure. Crystal data: 1, C₁₆H₁₆MnN₂O₄, M _r = 355.25, monoclinic, P2₁/c (No. 14), a = 10.6534(2) Å, b = 4.3990(1) Å, c = 15.5733(5) Å, β = 95.1827(10)°, V = 726.85(3) ų, Z = 2, R(F) = 0.026, wR(F ²) = 0.067. 2, C₁₆H₁₆CoN₂O₄, M _r = 359.24, monoclinic, P2₁/c (No. 14), a = 10.6131(10) Å, b = 4.3374(4) Å, c = 15.3556(17) Å, β = 95.473(4)°, V = 703.65(12) ų, Z = 2, R(F) = 0.041, wR(F ²) = 0.091. 3, C₁₆H₁₆N₂NiO₄, M _r = 359.02, monoclinic, P2₁/c (No. 14), a = 10.6374(4) Å, b = 4.2964(2) Å, c = 15.2827(8) Å, β = 95.9744(14)°, V = 694.66(6) ų, Z = 2, R(F) = 0.028, wR(F ²) = 0.070. 4, C₁₆H₁₆N₂O₄Zn, M _r = 365.68, monoclinic, P2₁/c (No. 14), a = 10.6385(5) Å, b = 4.2967(3) Å, c = 15.2844(8) Å, β = 95.941(3)°, V = 694.89(7) ų, Z = 2, R(F) = 0.038, wR(F ²) = 0.107.     

Electron diffraction and quantum-chemical studies of the molecular structure of 2-methylbenzenesulfochloride

A combined electron diffraction and quantum-chemical (MP2/6-31G**) study of the molecular structure of 2-methylbenzenesulfochloride at 336(5) K was carried out. It was found that the gas phase contained only one conformer, C ₁. The following structural parameters were obtained: r _h1(C-H)_av = 1.095(8) Å, r _h1(C-C)_Ph = 1.402(4) Å, r _h1(C_Ph-C_meth) = 1.507(13) Å, r _h1(C_Ph-S) = 1.763(6) Å, r _h1(S=O) = 1.418(4) Å, r _h1(S-Cl) = 2.048(5) Å, ∠(H-C-H)_meth/av = 107.3(96)°, ∠(Cl-S-O)_av = 106.4(3)°, ∠C_Ph-S-Cl = 100.8(9), ∠O=S=O = 120.8(10)°. The C_C-C_S-S-Cl torsion angle that defines the position of the S-Cl bond relative to the plane of the benzene ring is 75.6(20)°. The B3LYP/6-311+G** calculated barriers of internal rotation of the methyl and sulfochloride groups are 1.2 kcal/mol and V ₀₁ = 10.2 (V ₀₂ = 4.1) kcal/mol, respectively.     

Gas electron diffraction and quantum chemical studies of the molecular structure of 2-nitrobenzenesulfonic acid

A combined gas electron diffraction and quantum chemical (B3LYP/6-311+G**, B3LYP/cc-pVTZ) study of the molecular structure of 2-nitrobenzenesulfonic acid (2-NBSA) is performed. Quantum chemical calculations show that the 2-NBSA molecule has five conformers, and the Gibbs energy of one of them is lower by more than 4.5 kcal/mol than the energy of the other conformers. It is found experimentally that the saturated vapor of 2-NBSA at T = 394(5) K contains only the low-energy conformer that has an intramolecular hydrogen bond between the H atom of the hydroxyl group and one of the O atoms of the NO₂ group. The C-C-S-O(H) torsion angle determining the position of the S-O(H) bond is ?72(7)°, while the NO₂ group is substantially turned relative to the benzene ring plane (C1-C2-N-O = 40(5)°). The following experimental values of the internuclear distances are obtained for this conformer (Å): r _h1(C-H)_av = 1.07(2), r _h1(C-C)_av = 1.401(4), r _h1(C-S) = 1.767(6), r _h1(S=O)_av = 1.412(4), r _h1(S-O) = 1.560(6), r _h1(N-O)_av = 1.217(5), r _h1(C-N) = 1.461(8), r _h1(O-H) = 0.99(3).     

Theoretical prediction of the new high-density lithium boride LiB<Subscript>11</Subscript> with polymorphism and pseudoplasticity

We predict the possibility of existence of the new lithium boride LiB₁₁ with polymorphism. For energy reasons, the preferred type is α′-LiB₁₁ (trigonal space group R3m, a _h = 0.4982 nm, c _h = 1.1123 nm, z _h = 3, ρ = 2.63 g/cm³), with a framework built of tetrahedra and one-capped octahedra. α′-LiB₁₁ is pseudoplastic because of twinning via the high-symmetry state of α-LiB₁₁ (cubic space group \(F\bar 43m\), a = 0.6810 nm, z = 4, ρ = 2.65 g/cm³) and a bipolaron semiconductor. α → α′ transition is accompanied by the 0.0627-nm displacement of 1/11 B atoms. The β′ polymorph (tetragonal space group \(I\bar 4m2\), a = 0.4404 nm, c = 0.7708 nm, ρ = 2.80 g/cm³) is transformation hardened because of the transition to the α′ phase. We infer that LiB₁₁ formation is possible under high pressure.     

High-temperature heat capacity and thermodynamic properties of pyrovanadate Pb<Subscript>2</Subscript>V<Subscript>2</Subscript>O<Subscript>7</Subscript> and orthovanadate Pb<Subscript>3</Subscript>(VO<Subscript>4</Subscript>)<Subscript>2</Subscript>

The heat capacities of Pb₂V₂O₇ and Pb₃(VO₄)₂ as a function of temperature in the range 350–965 K have been studied by the differential scanning calorimetry method. The C_P = f(T) curve for Pb₂V₂O₇ is described by the equation C_p = (230.76 ± 0.51) + (73.60 ± 0.50)×10^-3T ? (18.38 ± 0.54)×10⁵T^-2 in the entire temperature range. For Pb₃(VO₄)₂, there is a well-pronounced extreme point in the C_P = f(T) curve at T = 371.5 K, which is caused by the existence of a structural phase transition. The thermodynamic properties of the oxide compounds have been calculated.     

Electron diffraction and quantum-chemical study of the molecular structure of 2-chlorobenzenesulfonyl chloride

The molecular structure of 2-chlorobenzenesulfonyl chloride was studied by electron diffraction and quantum-chemical (2/6-31G**, B3LYP/6-311++G**) methods at 337(3) K. Only one (C ₁) conformer was found in the gas phase. The following structural parameters were obtained: r _h1(C-H)_av = 1.105(6) Å, r _h1(C-C)_av = 1.398(3) Å, r _h1(C-S) = 1.783(11) Å, r _h1(S=O)_av = 1.427(3) Å, r _h1(S-Cl) = 2.048(4) Å, r _h1(C-Cl) = 1.731(9) Å, ∠(C-S=O1) = 109.9(8) °, ∠(C-S=O2) = 106.9(8) °, ∠(Cl1-S-O1) = 107.3(4) °, ∠(Cl1-S-O2) = 106.4(4) ∠, ∠C-S-Cl = 102.1(6) °, ∠O=S=O = 122.3(11) °. The C2-C1-S-Cl1 torsion angle that defines the position of the S-Cl bond relative to the plane of the benzene ring was 69.7(8) °. The B3LYP/6-311++G** calculated barriers of internal rotation of the sulfonyl chloride group were V ₀₁ = 9.7 kcal/mol and V ₀₂ = 3.6 kcal/mol.     

Oxygen isotope exchange in praseodymium nickelate

Oxygen surface exchange kinetics and diffusion were studied in Pr₂NiO_4?+?δ (PNO) by the isotope exchange method with gas phase equilibration in the temperature range of 600–800 °C and oxygen pressure range of 0.33–1.62 kPa. The oxygen heterogeneous exchange rate (r_H), oxygen diffusion coefficient (D), rates of oxygen dissociative adsorption (r_a), and oxygen incorporation (r_i) were calculated along with the apparent activation energies of oxygen surface exchange and diffusion processes. The temperature dependence of r_H was found to benon-linear in Arrhenius coordinates. The apparent activation energy changed from 1.4?±?0.2 eV at T?>?700 °C to 2.0?±?0.1 eV. This might be attributed to the change in the rate-determining stage of oxygen exchange for Pr₂NiO_4?+?δ at T ~?700 °C, because of a shift in the ratio between r_a and r_i caused by the difference in their activation energies. Possible reasons for the observed changes in the rate-determining stage are discussed.     

Potassium decamolybdodiferrate(III): Synthesis and characterization

Potassium decamolybdodiferrate(III) of composition K₆[Fe₂Mo₁₀O₃₄(OH)₄] · 7H₂O (compound I) is synthesized and characterized by IR spectroscopy, thermogravimetry, and powder X-ray diffraction. The crystals of compound I are monoclinic with a = 9.7482 Å, b = 6.5663 Å, c = 7.8453 Å, β = 116.81°, V = 448.15 ų, ρ = 3.115 g/cm³.     

Constants of acid‒base equilibria in an aqueous amikacin aminoglycoside solution at 298 K

The acid dissociation constants of form pK₁ = 7.34 ± 0.01, pK₂ = 7.84 ± 0.01, pK₃ = 8.77 ± 0.01, pK₄ = 9.49 ± 0.01, and pK₅ = 10.70 ± 0.02 of cationic amikacin are determined by pH-metric titration at 25°C against the background of 0.1 mol/L KNO₃. K₁, K₂, K₃, and K₄ correspond to the dissociation of protons coordinated to amino groups, while K₅ characterizes the dissociation of the hydroxyl hydrogen atom, testifying to the amphoteric character of amikacin molecules. Applying density functional theory (DFT) with the B3LYP hybrid functional and the 6-311G**++ basis set, the partial charges on the atoms of an amikacin molecule are calculated. It is concluded that the dissociation of H(55)hydrogen atom occurs with a greatest partial charge of +0.53631.     

Density of N<Subscript>2</Subscript>O Solutions in Perfluorodecalin As a Function of Concentration

The dependence of density ρ of nitrogen oxide N₂O solutions in perfluorodecalin on the N₂O concentration is measured. At a constant temperature, this dependence has a linear character: ρ = аx + b. Coefficients a and b are tabulated for five temperatures: 293, 298, 303, 313, and 328 K. These data allow us to control the N₂O concentration in perfluorodecalin.     

Crystal structure and antitumor activities of a dinuclear cobalt(II) complex based on <Emphasis Type="Italic">meso</Emphasis>-1,2,3,4-tetra(1H-benzo[<Emphasis Type="Italic">d</Emphasis>]imidazol-2-yl)butane

The [Co₂(tbb)Cl₄]?4DMF complex, where tbb is meso-1,2,3,4-tetra(1H-benzo[d]imidazol-2-yl)butane, is synthesized and characterized by single crystal X-ray diffraction. For the complex: C₄₄H₅₄Co₂C_l4N₁₂O₄, M_r = 1074.65, monoclinic crystal system, space group P21/n, a = 9.2350(13) Å, b = 11.3566(15) Å, c = 23.879(3) Å, β = 90.547(2)°, V = 2504.3(6) ų, Z = 2, D_c = 1.425 g/cm³, λ = 0.71073 Å, μ(MoK_α) = = 0.929 mm^–1, F(000) = 1112, S = 1.047, R = 0.0765, and wR = 0.2110 for 13668 observed reflections with I > 2σ(I). It is a neutral dinuclear complex. One meso-1,2,3,4-tetra(1H-benzo[d]imidazol-2-yl)butane coordinates two cobalt(II) ions. Each cobalt(II) ion is formed by two tbb nitrogen atoms and two chloride ions. The antiproliferative activities of the complex are screened by MTT assay against Eca109 cancer cells. The complex exhibits inhibition on the growth of Eca109 cancer cells with IC₅₀ of 22.1±6.7 μM after 48 h treatment. The cobalt complex has potential application in treatment of Eca109 cancer. CCDC 1015791.     

Electron diffraction study of molecular structure of mebicar

The structure of the mebicar molecule has been studied by gas-phase electron-diffractometry using quantum chemical calculations. An eclipsed conformation along the C-C bond (torsion angle ?(H-C-C-H) = 10°) and flattened semi-chair conformations of cyclic fragments have been found. The bond lengths (r _g ) and angles (∠α) show the following average values: r(C-C) 1.576(3) Å, r(C-N) 1.460(3) Å, r(C(O)-N) 1.390(4) Å, r(C=O) 1.211(5) Å, r(C-H) 1.090(5) Å, ∠CCN 103.0(5)°, ∠CNC(O) 112.2(1)°, ∠CNC 122.4(1)°. The dihedral angle between the cyclic fragments is 116.6°.     

Syntheses and characterization of two 1D Cu(II) coordination polymers with 2,2′:6′,2″-terpyridine ligand

The solution reactions of CuCl₂ with 2,2′:6′,2″-terpyridine (Terpy) and dicarboxylic acid (glutaric acid or suberic acid) afforded two 1D coordination polymers [Cu(Terpy)(C₅H₆O₄)] _n (I) and [Cu(Terpy)(C₈H₁₂O₄)] · 3H₂O (II) and their structures were characterized by IR, TG-DTA, and single-crystal X-ray diffraction. Crystallographic data for I: C₂₀H₁₆CuN₃O₄, M _r = 425.90, monoclinic, space group C2/c, a = 10.335(2), b = 21.193(4), c = 8.580(2) Å, β = 111.99(3)°, V = 1742.5(6) ų, Z = 4, ρ _c = 1.623 g/cm³, F(000) = 872, R = 0.0304 and wR = 0.0915; and those for II: C₂₃H₂₉CuN₃O₇, M _r = 523.03, triclinic, space group P \(\bar 1\), a = 8.362(2), b = 10.605(2), c = 14.617(3) Å, α = 73.26(3)°, β = 86.23(3)°, γ = 69.45(3)°, V = 1161.3(4) ų, Z = 2, ρ _c = 1.496 g/cm³, F(000) = 546, R = 0.0636 and wR = 0.1106. X-ray diffracion studies reveal that both complexes I and II feature 1D chain. The 1D polymer chains are connected by π-π-stacking interactions to generate 2D supramolecular layers.