Anharmonic Effect in CH<Subscript>3</Subscript>CH<Subscript>2</Subscript>C(=O)OCH<Subscript>2</Subscript>CH<Subscript>3</Subscript> Decomposition

In this paper, using the B3LYP functional and CCSD(T) method with 6-311++G** basis set, the harmonic and anharmonic rate constants in the unimolecular dissociation of ethyl propanoate have been calculated using Rice–Ramsperger–Kassel–Marcus theory. The anharmonic rate constants of the title reaction have also been examined, the comparison shows that, the anharmonic effect especially in the case of high total energies and temperature for channels 3 to 6 is significant, so that the anharmonic effect cannot be neglected for unimolecular dissociation reaction of CH₃CH₂C(=O)OCH₂CH₃ both in microcanonical and canonical systems.     

Synthesis,spectral and structural studies of oxovanadium(IV/V) complexes derived from 2-hydroxyacetophenone-3-hydroxy-2-naphthoylhydrazone: polymorphs of oxovanadium(V) complex [VOL(OCH<Subscript>3</Subscript>)]

Abstract  

Oxovanadium(IV/V) complexes of 2-hydroxyacetophenone-3-hydroxy-2-naphthoylhydrazone (H₂L) have been synthesized and characterized. The complexes were characterized by elemental analyses, IR, electronic and EPR spectra. The oxovanadium(V) complex [VOL(OCH₃)] is crystallized in two polymorphic forms, denoted by 1a and 1b, with space groups Pn2₁a and P_[`1] P_{{\bar{1}}} , respectively. Both have distorted square pyramidal structures.     

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⁺ ).     

Theoretical study on the reaction mechanism of the OH-initiated oxidation of CH<Subscript>2</Subscript>=C(CH<Subscript>3</Subscript>)CH<Subscript>2</Subscript>CH<Subscript>2</Subscript>OH

In the present work, the detailed reaction mechanism and possible products of the OH-initiated oxidation of CH₂=C(CH₃)CH₂CH₂OH (MBO331) have been revealed theoretically for the first time. The potential energy surfaces of various reaction channels both in the absence and presence of O₂ and NO are evaluated at the CCSD(T)/6−31++G(d,p)//MP2(full)/6−311G(d,p)+ZPE*0.95 level. The major products of HCHO + CH₃C(O)CH₂CH₂OH predicted for the title reaction in the presence of O₂ and NO are in agreement with those of similar reactions of unsaturated alcohols with OH radical.     

Indium strontium hydrogen phosphate SrIn<Subscript>2</Subscript>[PO<Subscript>3</Subscript>(OH)]<Subscript>4</Subscript>: Synthesis and crystal structure

Indium strontium hydrogen nitrate SrIn₂[PO₃(OH)]₄ was synthesized under mild hydrothermal conditions (T = 180 or 200°C) and characterized using IR spectroscopy, chemical analysis, and thermal analysis. A structure model obtained ab initio was refined by the Rietveld method: a= 9.6412(1) Å, b = 13.763(1) Å, c = 9.3579(1) Å, R _obs = 0.0183, R _p = 0.0493 (space group B22₁2, Z = 4). The acentricity of the structure was confirmed by SHG tests (I _2ω/I _2ω(SiO2) ≈ 2.0). In the SrIn₂[PO₃(OH)]₄ structure, indium atoms reside in distorted InO₆ octahedra and form, together with PO₃(OH) tetrahedra, a mixed 3D structure {In₂[PO₃(OH)]₄} _3∞ ^2? whose voids are occupied by Sr²⁺ cations (CN = 8). The block-dimer In₂(HPO₄)₁₀ is the most informative unit of the framework. Blocks are condensed into infinite columns running in the [101] direction. The compound is thermally stable up to 400°C.     

Synthesis and crystal structure of (NH<Subscript>4</Subscript>)(CN<Subscript>3</Subscript>H<Subscript>6</Subscript>)[UO<Subscript>2</Subscript>(SeO<Subscript>3</Subscript>)<Subscript>2</Subscript>]

Single crystals of (NH₄)(CN₃H₆)[UO₂(SeO₃)₂] (I) are synthesized and studied by X-ray diffraction analysis. The compound crystallizes in the triclinic crystal system with the unit cell parameters: a = 7.0051(2) Å, b = 9.4234(3) Å, c = 9.5408(3) Å, α = 88.727(1)°, β = 70.565(1)°, γ= 77.034(1)°, space group P ₁, Z = 2, R = 0.0224. The main structural units of crystals I are the [UO₂(SeO₃)₂]^2? chains of the crystal-chemical group AB²B₁₁ (A = UO ₂ ²⁺ , B₂= SeO₃ ^2?, B₁₁= SeO₃ ^2?) of the uranyl complexes. The uranium-containing complexes are joined into a three-dimensional framework by the ammonium and guanidinium ions and a system of hydrogen bonds.     

The structures and stability of pentacoordinate germylenoid PhCH<Subscript>2</Subscript>(OH)CH<Subscript>3</Subscript>GeLiF

The structures and stability of pentacoordinate germylenoid PhCH₂(OH)CH₃GeLiF were first theoretically studied by density functional theory. Two equilibrium structures, the three-membered ring (1a) and the p-complex (1b) structures, were located. Their energy are in the order of 1b > 1a. The Ge-O coordination energies at the B3LYP/6-311+G(d, p) level are 13.6 and 0.2 kJ/mol in 1a and 1b, respectively. The insertion reactions with CH₃F indicate that germylenoid PhCH₂(OH)CH₃GeLiF is more stable than germylene PhCH₂(OH)CH₃Ge. The insertion barrier of 1a with CH₃F is only 3.1 kJ/mol higher than that of PhCH₃CH₃GeLiF, indicating that the oxygen coordination PhCH₂(OH)CH₃GeLiF has the same stability as PhCH₃CH₃GeLiF.     

Synthesis and crystal structures of dimeric schiff base oxovanadium(V) complexes with antimicrobial activity

Two new dimeric oxovanadium(V) complexes, [VO₂L₁]₂ · 2H₂O (I) and [VO₂L₂]₂ (II), where L¹ and L² are the monoanionic form of 5-methoxy-2-[(2-methylaminoethylimino)methyl]phenol (HL¹) and 5-diethylamino-2-[(2-methylaminoethylimino)methyl]phenol (HL²), respectively, have been synthesized and characterized by elemental analysis, FT-IR spectra, and single crystal X-ray determination. The crystal of I is monoclinic: space group P2₁, a = 6.858(2), b = 16.630(3), c = 12.306(2) Å, β = 103.985(2)°, V = 1361.9(5) ų, Z = 2. The crystal of II is triclinic: space group $P\bar 1$ , a = 7.378(2), b = 8.838(2), c = 13.312(3) Å, α = 102.576(2)°, β = 92.044(2)°, γ = 113.017(2)°, V = 772.7(3) ų, Z = 2. The V...V distances are 3.140(1) Å in I and 3.254(1) Å in II. The V atoms in the complexes are in octahedral coordination. The effect of the complexes on the antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans was studied.     

Synthesis,crystal structures,and antibacterial activities of Schiff base zinc(II) complexes [Zn(L<Superscript>1</Superscript>)<Subscript>2</Subscript>] and [Zn(L<Superscript>2</Superscript>)<Subscript>2</Subscript>]

The reaction of cyclopentylamine with 2-hydroxy-1-naphthaldehyde and 5-nitrosalicylaldehyde, respectively, in methanol affords two new Schiff bases, 1-(cyclopentyliminomethyl)naphthalen-2-ol (HL¹) and 4-nitro-2-(cyclopentyliminomethyl)phenol (HL²). Two new zinc(II) complexes, [Zn(L¹)₂] (I) and [Zn(L²)₂] (II), derived from the Schiff bases, have been prepared and characterized by single-crystal X-ray diffraction, FT-IR, and elemental analysis. Complex I crystallizes in the monoclinic space group P2₁/c with a = 17.834(4), b = 14.738(3), c = 9.868(2) Å, β = 91.20(3)°, V = 2593.1(9) ų, Z = 4. Complex II crystallizes in the triclinic space group P \(\bar 1\) with a = 10.206(1), b = 10.502(1), c = 12.554(1) Å, α = 66.771(2)°, β = 78.133(2)°, γ = 76.292(2)°, V = 1191.8(1) ų, Z = 2. The Zn atom in each complex is coordinated by two N and two O atoms from two Schiff base ligands, forming a tetrahedral geometry. The Schiff bases and the complexes were assayed for antibacterial activities.     

Ion mobility and conductivity in the Li(NH<Subscript>3</Subscript>CH<Subscript>2</Subscript>COO)(NO<Subscript>3</Subscript>) compound

(⁷Li, ¹H) NMR and impedance spectroscopy methods are used to study the ion mobility and conductivity in a complex of the composition Li(NH₃CH₂COO)(NO₃) (I), which has a layered crystal structure. The character of ion motions in lithium and proton sublattices with temperature variation is considered; the types of motions and temperature ranges in which they occur are determined. It is found that above 350 K the dominant process in the lithium sublattice of the compound is Li⁺ ion diffusion. Possible migration paths of lithium ions in the lattice of the compound are analyzed. The specific conductivity of the compound is found to be 2.4×10^–6 S/cm at 393 K.     

Effect of structural features of molecules (Cl<Subscript>3</Subscript>PNZ)<Subscript>2</Subscript> (Z = CH<Subscript>3</Subscript> and CH<Subscript>2</Subscript>CH<Subscript>2</Subscript>Cl) on the position exchange of chlorine atoms in the P-Cl fragments

Based on the analysis of structural parameters of molecules (Cl₃PNCH₃)₂ (I) and (Cl₃PNCH₂CH₂Cl)₂ (II) by the quantum-chemical nonempirical calculations the following was revealed. The structure of I and II dimers has geometric features, which have a decisive influence on the degree of inhibition of positional exchange of the chlorine atoms in the P-Cl fragments known for the chlorine derivatives of pentacoordinated phosphorus atom. The obstacles to this dynamic process in the mentioned intramolecular dimers is shown to result from the spatial nonvalent interactions due to the short contacts of the chlorine and hydrogen atoms.     

Dinuclear complex of gold(III) with 1,3-diaminopropane (HL), [Au<Subscript>2</Subscript>(HL)(L)<Subscript>2</Subscript>](ClO<Subscript>4</Subscript>)<Subscript>3</Subscript>(OH): Synthesis and crystal and molecular structures

The dinuclear gold(III) complex, [Au₂(HL)(L)₂](ClO₄)₃(OH) (I) (HL = 1,3-diaminopropane), with two amide bridges has been synthesized for the first time. According to the X-ray diffraction data, the crystal structure of complex I consists of the complex cations [Au₂(HL)(L)₂]⁴⁺ and anions ClO₄⁻ and OH⁻. The coordination sites AuN₄ are insignificantly distorted squares. In the four-membered ring Au₂N₂, the gold atoms are bound by the bridging nitrogen atoms of the deprotonated primary amine.     

Synthesis,DNA-binding and photocleavage studies of cobalt(III) complexes [Co(bpy)<Subscript>2</Subscript>(dpta)]<Superscript>3+</Superscript> and [Co(bpy)<Subscript>2</Subscript>(amtp)]<Superscript>3+</Superscript>

Two novel cobalt(III) mixed-polypyridyl complexes [Co(bpy)₂(dpta)]³⁺ and [Co(bpy)₂(amtp)]³⁺ (bpy = 2,2′-bipyridine, dpta = dipyrido-[3,2-a;2′,3′-c]-thien-[3,4-c]azine, amtp = 3-amino-1,2,4-triazino[5,6-f]-1,10-phenanthroline) have been synthesized and characterized. The interaction of Co^III complexes with calf thymus DNA was investigated by spectroscopic and viscosity measurements. Results suggest that the two complexes bind to DNA via an intercalative mode. Moreover, Co^III complexes have been found to promote the photocleavage of plasmid DNA pBR322 under irradiation at 365 nm. The mechanism studies reveal that hydroxyl radical (OH^•) is likely to be the reactive species responsible for the cleavage of plasmid DNA by [Co(bpy)₂(dpta)]³⁺ and superoxide anion radical (O ₂ ^•− ) acts as the key role in the cleavage reaction of plasmid DNA by [Co(bpy)₂(amtp)]³⁺.     

Theoretical and Experimental Studies on a Metallorganic Complex of (Isopropylxanthato)(Phenyl)Mercury(I) [Hg(I)(C<Subscript>6</Subscript>H<Subscript>5</Subscript>)(C<Subscript>4</Subscript>H<Subscript>7</Subscript>OS<Subscript>2</Subscript>)]

The title compound, (isopropylxanthato)(phenyl)mercury(I), was synthesized and characterized by elemental analysis, IR and thermogravimetric analysis. Density functional theory (DFT) method calculations were performed at B3LYP/CEP-121G and B3LYP/CEP-31G levels of theory, respectively. Vibrational frequencies were predicted, assigned, compared with the experimental values, and they are supported each other. The calculated results show that the strength of bond Hg—C is stronger than that of Hg—S, which is good agreement with the experimental data. The calculations of the second order optical nonlinearity and electronic absorption spectra are also performed.     

K<Subscript>3</Subscript>VO<Subscript>2</Subscript>(SO<Subscript>4</Subscript>)<Subscript>2</Subscript>: Formation conditions,crystal structure,and physicochemical properties

Potassium oxosulfatovanadate(V) K₃VO₂(SO₄)₂ has been obtained by solid-phase synthesis from K₂SO₄, K₂S₂O₇, and V₂O₅ (2: 1: 1), and its formation conditions, crystal structure, and physiochemical properties have been studied. The conversions of K₃VO₂(SO₄)₂ in contact with potassium vanadates and other potassium oxosulfatovanadates(V) are considered in terms of phase relations in the K₂O-V₂O₅-SO₃ system, which models the active component of vanadium catalysts for sulfur dioxide oxidation into sulfur trioxide. The X-ray diffraction pattern of K₃VO₂(SO₄)₂ is indexed in the monoclinic system (space group P2₁) with unit cell parameters of a = 10.0408(1) Å, b = 7.2312(1) Å, c = 7.3821(1) Å, β = 104.457(1)°, Z = 2, and V = 519.02 ų. The crystal structure of K₃VO₂(SO₄)₂ is built from [VO₂(SO₄)₂]^3? complex anions, in which the vanadium atom is in an octahedral oxygen environment formed by two terminal oxygen atoms (V-O(6) = 1.605(7) Å, V-O(10) = 1.619(7) Å and four oxygen atoms of the two chelating sulfate anions. The vibrational spectra of K₃VO₂(SO₄)₂ are analyzed using these structural data.     

Synthesis and crystal structure of two complexes [Cu<Subscript>2</Subscript>(NiL)<Subscript>2</Subscript>Cl<Subscript>4</Subscript>] and [Cd<Subscript>2</Subscript>(CuL)<Subscript>2</Subscript>Cl<Subscript>4</Subscript>]

Macrocyclic and supermolecular complexes [Cu₂(NiL)₂Cl₄] (I) and [Cd₂(CuL)₂Cl₄] (II) (H₂L = 2,3-dioxo-5,6,14,15-dibenzo-1,4,8,12-tetraazacyclo-pentadeca-7,13-diene) have been synthesized and structurally determined by X-ray diffraction and IR spectrum. Complex I crystallizes in the monoclinic system with P2₁/n group, a = 10.9019(15), b = 14.3589(19), c = 12.4748(17) 0A, β = 108.645(2)°, Z = 4. Complex II crystallizes in the monoclinic system with P2₁/n group, a = 10.9784(16), b = 14.580(2), c = 12.8904(18) Å, β = 109.339(2)°, Z = 4.     

Computational study on the reaction of CH<Subscript>3</Subscript>SCH<Subscript>2</Subscript>CH<Subscript>3</Subscript> with OH radical: mechanism and enthalpy of formation

The reaction mechanism of CH₃SCH₂CH₃ with OH radical is studied at the CCSD(T)/6-311+G(3df,p)//MP2/6-31+G(2d,p) level of theory. Three hydrogen abstraction channels, one substitution process and five addition–elimination channels are identified in the title reaction. The result shows hydrogen abstraction is dominant. Substitution process and addition–elimination reactions may be negligible because of the high barrier heights. Enthalpies of formation [ \Updelta_f H_{(298.15\textK)}^o \Updelta_{f} H_{(298.15{\text{K}})}^{o} ] of the reactants and products are evaluated at the CBS-QB3, G3 and G3MP2 levels of theory, respectively. It is found that the calculated enthalpies of formation by the aforementioned three methods are in consistent with the available experimental data. Rate constants and branching ratios are estimated by means of the conventional transition state theory with the Wigner tunneling correction over the temperature range of 200–900 K. The calculation shows that the formations of P1 (CH₂SCH₂CH₃ + H₂O) and P2 (CH₃SCHCH₃ + H₂O) are major products during 200–900 K. The three-parameter expressions for the total rate constant is fitted to be k_\texttotal = 1.45 ×10 ^{- 21} T^3.24 exp( - 1384.54/T) k_{\text{total}} = 1.45 \times 10^{ - 21} T^{3.24} \exp ( - 1384.54/T) cm³ molecule⁻¹ s⁻¹ from 200 to 900 K.