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.     

Cyclothiomethylation of carboxylic acid hydrazides with aldehydes and H<Subscript>2</Subscript>S

The cyclothiomethylation of carboxylic acid hydrazides RCONHNH₂ (R = C₅H₄N, Ph, 2-MeOC₆H₄, or 4-HOC₆H₄CH₂) with formaldehyde and H₂S at 70 °C affords predominantly the corresponding N-(1,3,5-dithiazinan-5-yl)amides, whereas this reaction at 0–−50 °C gives a mixture of the latter compounds with 3-acyl-1,3,4-thiadiazolidines. N-(1,3,5-Dithiazinan-5-yl)-amides were selectively synthesized by the reaction of carboxylic acid hydrazides with formaldehyde and H₂S in the presence of BuONa in BuOH.     

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.     

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.     

Study on the oxygen exchange capacities of Ce<Subscript>2</Subscript>Sn<Subscript>2</Subscript>O<Subscript>7</Subscript> pyrochlore

Ce₂Sn₂O₇ pyrochlore was synthesized by a hydrothermal method. X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the composition and valence state of the sample. The oxygen exchange property of the Ce₂Sn₂O₇ phase was measured by an oxidation reaction in sealed air atmosphere and a followed reduction reaction in 5% H₂-95% N₂ atmosphere. Gas chromatography (GC) was used to analyze the oxygen change in the reaction. The results show that Ce₂Sn₂O₇ sample has excellent oxygen absorption capacity at 250°C as Ce³⁺ ions are oxidized to Ce⁴⁺ ions. The oxidized sample can be reduced by 5% H₂-95% N₂. The refreshed sample remains the capacity of oxygen absorption, while the oxygen exchange capacity degrades with the reduction times.     

Complexation of TiF<Subscript>4</Subscript> with PhP(O)[CH<Subscript>2</Subscript>C(O)NMe<Subscript>2</Subscript>]<Subscript>2</Subscript> in CH<Subscript>2</Subscript>Cl<Subscript>2</Subscript>: Appearance of a Chiral Center at Chelate Coordination

The reaction of TiF₄ with PhP(O)[CH₂C(O)NMe₂]₂ in CH₂Cl₂ has been studied by ¹⁹F NMR spectroscopy. It has been found that the major reaction products are chelate tetrafluoro complex (η²-L)TiF₄ where the ligand is coordinated to the titanium ion through the P=O and C=O groups and cis-TiF₄(ОР···L)₂ where both ligands are coordinated to the central ion through the more basic P=O groups. Spectral features of the tetrafluoro chelate have been studied, which have been attributed for the first time to the appearance of a chiral center at chelate coordination. The character of manifestation of conformational isomerism of the chelate ring and chiral center in the chelating ligand in mixed octahedral complexes of d⁰ transition metal fluorides in ¹⁹F NMR spectra is discussed.     

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.     

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.     

Standard molar enthalpy of formation of CH<Subscript>3</Subscript>(CH<Subscript>3</Subscript>SCH<Subscript>2</Subscript>)SO,methyl methylthiomethyl sulfoxide

Summary The standard molar enthalpy of formation of methyl methylthiomethyl sulfoxide, CH₃(CH₃SCH₂)SO, at T=298.15 K in the liquid state was determined to be -199.4±1.5 kJ mol^-1 by means of oxygen rotating-bomb combustion calorimetry.     

A New Molybdophosphate Constructed From {Mo<Stack><Subscript>2</Subscript><Superscript>V</Superscript></Stack>O<Subscript>4</Subscript>(H<Subscript>2</Subscript>O)<Subscript>6</Subscript>}<Superscript>2+</Superscript> and 1-Hydroxyethylidenediphosphonate

A new molybdophosphate (NH₄)₈{Mo₂^VO₄[(Mo₂^VIO₆)CH₃C(O)(PO₃)₂]₂}·14H₂O (1), has been synthesized by the reaction of {Mo₂^VO₄(H₂O)₆}²⁺ fragments with 1-hydroxyethylidenediphosphonate (hedp HOC(CH₃)(PO₃H₂)₂), and it is characterized by ³¹P NMR, IR, UV, element analysis, TG and single-crystal X-ray analysis. The structure analysis reveals that the polyoxoanion can be described as two {(Mo₂^VIO₆)(CH₃C(O)(PO₃)₂} units connected by a {Mo₂^VO₄}²⁺ moiety. In the structure, the six Mo atoms are arranged into a new “W-shaped” structure, which represents a new kind of molybdophosphate.     

Hydrogen generation from H<Subscript>2</Subscript>O/H<Subscript>2</Subscript>O<Subscript>2</Subscript>/MnWO<Subscript>4</Subscript> system

Hydrogen gas as a clear energy resource was found to be largely bubbled from a H₂O/H₂O₂/MnWO₄ system. MnWO₄ powder was fabricated by an aqueous reaction method. The powder was characterized with X-ray diffraction (XRD), transmission electron microscope (TEM), and X-ray photoelectron spectrometry (XPS). The efficiency of the hydrogen generation increases with an increase in initial pH in the appropriate range, H₂O₂ proportion, MnWO₄ proportion, and intensity of light resource. Calcining at 400 °C for 1 h can make the MnWO₄ powder synthesized by an aqueous reaction more effective for H₂ generation and more stable in higher initial pH. The MnWO₄ catalyst shows a long-term stability for photocatalytic H₂ generation. A mechanism was suggested for the hydrogen generation from the H₂O/H₂O₂/MnWO₄ system together with XPS analysis.     

Theoretical studies on the pentacoordinate silylenoid PhCH<Subscript>2</Subscript>(NH<Subscript>2</Subscript>)CH<Subscript>3</Subscript>SiLiF

The structures of pentacoordinate silylenoid PhCH₂(NH₂)CH₃SiLiF were studied by density functional theory at the B3LYP/6-31G(d) level. Three equilibrium structures, the three-membered ring (1), the p-complex (2), and the σ-complex (3) structures, were located. Their energies are in the order of 2 > 1 > 3 both in vacuum and in THF. To exploit the stability of PhCH₂(NH₂)CH₃SiLiF, the insertion reactions of 1 and PhCH₂(NH₂)CH₃Si into C–F have been investigated, respectively. The results show that the insertion of PhCH₂(NH₂)CH₃Si is more favorable. To probe the influence of amine-coordination to the stability of PhCH₂(NH₂)CH₃SiLiF, the insertion reaction of PhCH₃CH₃SiLiF was also investigated. The calculations indicate that the insertion of PhCH₃CH₃SiLiF is more favorable than that of 1. So the N atom plays an important role on the stability of silylenoid PhCH₂(NH₂)CH₃SiLiF.     

Synthesis of cyclopropane-containing organoaluminum compounds by the reaction of acetylenes with CH<Subscript>2</Subscript>I<Subscript>2</Subscript> and Et<Subscript>3</Subscript>Al

Reactions of disubstituted and terminal acetylenes with CH₂I₂ and Et₃Al in the molar ratio 1: 4: 6 lead to the selective formation of organoaluminum compounds containing di-, tri-, or tetrasubstituted cyclopropane fragments depending on the nature of acetylene and reaction conditions.     

Structures and mutual transformations of isomers of germylium ions (CH<Subscript>3</Subscript>)H<Subscript>2</Subscript>Ge<Superscript>+</Superscript> and (CH<Subscript>3</Subscript>)<Subscript>2</Subscript>HGe<Superscript>+</Superscript> and their silicon analogs

The potential energy surfaces of the (CH₃)_nH_3?n M⁺ ions, where n = 1, 2; M = Si, Ge, were scanned using the B3LYP method with 6–31G* and aug-cc-pVDZ basis sets. The major attention was given to isomeric species having the form of complexes of the HM⁺ and CH₃M⁺ ions with hydrogen, methane, and ethane molecules. These species were characterized previously neither by experimental nor by theoretical methods. It was found that these species become more stable in going from Si to Ge; the complex [CH₃Ge⁺CH₄] is the second isomer in the energy after (CH₃)₂HGe⁺. However, the heights of the activation barriers to formation of these complexes from the most stable isomer, though decreasing in going from Si to Ge, remain relatively high and, what is particularly important, somewhat exceed the activation barrier to formation of the complex [H₃Ge⁺·C₂H₄].     

Gas-sensitivity properties of nanoscale Au-In<Subscript>2</Subscript>O<Subscript>3</Subscript> materials

A possibility was demonstrated of producing the chemical sensors based on Au-In₂O₃ obtained using a sol-gel technology. The sensors exhibit high sensitivity and selectivity toward CO. The differences in gas-sensitivity properties of In₂O₃ sensor with respect to CO and CH₄ at different ways of doping with Au(III) was examined. The effect of the gold nanoparticles size and the state of the indium oxide surface on the characteristics of Au-In₂O₃ and Au/In₂O₃ sensors at the detection of CO and CH₄ was examined.     

Theoretical study on the reaction mechanism of (CH<Subscript>3</Subscript>)<Subscript>3</Subscript>CO<Superscript>.</Superscript> radical with NO

The reaction mechanism of (CH₃)₃CO^. radical with NO is theoretically investigated at the B3LYP/6-31G* level. The results show that the reaction is multi-channel in the single state and triplet state. The potential energy surfaces of reaction paths in the single state are lower than that in the triple state. The balance reaction: (CH₃)₃CONO⇔(CH₃)₃CO^.+NO, whose potential energy surface is the lowest in all the reaction paths, makes the probability of measuring (CH₃)₃CO^. radical increase. So NO may be considered as a stabilizing reagent for the (CH₃)₃CO^. radical.     

Formation of Cu<Superscript>I</Superscript>(CH<Subscript>3</Subscript>CN)<Subscript>4</Subscript>ClO<Subscript>4</Subscript> in the reactions of copper(II) perchlorate with acetonitrile in the presence of sulfur-containing organic compounds

Cu(ClO₄)₂·6H₂O was shown to react with 2,2′-[propane-1,3-diylbis(thio-2-phenylnemethylidene]-bis(3-pyridylamine) (I) or (5Z)-2-ethoxycarbonylmethyl-(2-pyridylmethylidene)-3,5-dihydro-4H-imidazol-4-one (II) in the presence of CH₃CN with the reduction of copper(II) to copper(I) and the formation of the tetrahedral complex Cu^I(CH₃CN)₄ClO₄ (III). In the course of the reaction the organic ligands I and II were oxidized to the corresponding sulfoxides.     

High-Efficient Conversion of CO<Subscript>2</Subscript> in AC-Pulsed Tornado Gliding Arc Plasma

An AC-pulsed tornado gliding arc plasma was employed for CO₂ conversion via CO₂ decomposition and dry reforming reactions. A stable and high-efficient constant arc length discharge mode was obtained in this plasma reactor. And then, CO₂ conversion was studied under this discharge mode. In the case of CH₄/CO₂ = 0, CO₂ was converted to CO and O₂ via the CO₂ decomposition reaction. Energy efficiency of 29 % was attained at CO₂ conversion of 6 %. With strong reducing agent CH₄ added into CO₂, the main contributor of CO₂ conversion changed from CO₂ decomposition to dry reforming of CH₄. Conversions of CH₄ and CO₂, energy efficiency and energy cost changed sharply at CO₂/CH₄ ratios lower than 1/4, while they changed slowly at CH₄/CO₂ ratios above 1/4. In the case of CH₄/CO₂ = 2/3, energy efficiency of 68 % and syngas energy cost of 1.6 eV/mole were achieved at CH₄ conversion of 29 % and CO₂ conversion of 22 %.     

Kinetics and mechanisms of homogeneous catalytic reactions: Part 13. Regioselective reduction of quinoline catalysed by Rh(acac)(CO)[P(<Superscript>t</Superscript>Bu)(CH<Subscript>2</Subscript>CH=CH<Subscript>2</Subscript>)<Subscript>2</Subscript>]

The complex Rh(acac)(CO)[P(^tBu)(CH₂CH=CH₂)₂] (1) proved to be an efficient precatalyst for the regioselective hydrogenation of quinoline (Q) to 1,2,3,4-tetrahydroquinoline (THQ) under mild reaction conditions (125 °C and 4 atm H₂). A kinetic study of this reaction led to the rate law:

$$ r \, = \{ K_{1} k_{2} /(1 \, + \, K_{1} {\text{H}}_{ 2} )\} [{\text{Rh}}][{\text{H}}_{ 2} ]^{2} $$

which becomes

$$ r \, = \, K_{1} k_{2} [{\text{Rh}}][{\text{H}}_{ 2} ]^{2} $$

at hydrogen pressures below 4 atm. The active catalytic species is the cationic complex {Rh(Q)₂(CO)[P(^tBu)(CH₂CH=CH₂)₂]}⁺ (2). The mechanism involves the partial hydrogenation of one coordinated Q of (2) to yield a complex containing a 1,2-dihydroquinoline (DHQ) ligand, {Rh(DHQ)(Q)(CO)[P(^tBu)(CH₂CH=CH₂)₂]}⁺ (3), followed by hydrogenation of the DHQ ligand to give THQ and a coordinatively unsaturated species {Rh(Q)(CO)[P(^tBu)(CH₂CH=CH₂)₂]}⁺ (4); this reaction is considered to be the rate-determining step. Coordination of a new Q molecule to (4) regenerates the active species (2) and restarts the catalytic cycle.

     

Adsorption study of xanthates on PbSO<Subscript>4</Subscript> by titration microcalorimetry

Isoperibol (pseudo-adiabatic) titration microcalorimetry was used to study the adsorption of various xanthates [CH₃(CH₂)_nOCS₂^?] at the PbSO₄/aqueous solution interface. The effect of the xanthate alkyl chain length (1n–3n) on the adsorption heat was evaluated. Xanthate adsorption isotherms were also determined. Furthermore, the amount of SO₄ into the aqueous solution was quantified to correlate it with the xanthate uptake by PbSO₄. The adsorption isotherms and the adsorption heat of the xanthates showed two steps. The first step occurred within a sub-monolayer xanthate coverage and was attributed to chemisorption of the xanthates exchanging surface hydroxyls to form CH₃(CH₂)_nOCS₂Pb. Lead xanthate (CH₃(CH₂)_nOCS₂)₂Pb multilayers formed in the second step, which was attributed to an ionic exchange chemical reaction between the xanthates and PbSO₄(aq). In the chemisorption step, the heat was found to be independent of the xanthate alkyl chain length and to linearly decrease in magnitude with the xanthate adsorption. In the multilayer formation step, the magnitude of the integral heat increased with the chain length of the xanthate. Heat contributions due to both the alkyl chain length and the interaction between the xanthate polar group and PbSO₄(aq) for the formation of lead xanthates are presented. Raman spectroscopy was used to characterize the lead xanthate multilayers on PbSO₄.