Thermokinetics on the reaction of formation of Dy[(C_5H_8NS_2)_3(C_(12)H_8N_2)]

The enthalpy change of formation of the reaction of hydrous dysprosium chloride with ammonium pyrrolidinedithiocarbamate (APDC) and 1,10-phenanthroline (o-phen·H2O) in absolute ethanol at 298.15 K has been determined as (-16.12±0.05) kJ·mol-1 by a microcalor-meter. Thermodynamic parameters (the activation enthalpy, the activation entropy and the activation free energy), rate constant and kinetics parameters (the apparent activation energy, the pre-exponential constant and the reaction order) of the reaction have also been calculated. The enthalpy change of the solid-phase reaction at 298.15 K has been obtained as (53.59±0.29) kJ·mol-1 by a thermochemistry cycle. The values of the enthalpy change of formation both in liquid-phase and solid-phase reaction indicated that the complex could only be synthesized in liquid-phase reaction.     

Degradation of anthracene, pyrene and benzo[a]-anthracene in aqueous solution by chlorine dioxide

Polycyclic aromatic hydrocarbons (PAHs) constitute an important group of micropollutants, which are known to be mutagenic, carcinogenic and/or co-carcinogenic and relatively persistent in the environment. The effects of chlorine dioxide (ClO2) on the degradation of anthracene (ANTH), pyrene (PYR) and benzo[a]anthracene (BaA) in aqueous solution were investigated using high performance liquid chromatography (HPLC). In preliminary experiments, it was observed that ClO2 could remove these three PAHs effectively within a short time. Several factors including reaction time, the concentration of ClO2 and pH of the reaction mixture influencing the degradation ratio of PAHs have been studied by batch experiments. The results showed that the degradation ratio of PAHs was affected by reaction time and the concentration of ClO2 instead of pH. The degradation ratio of ANTH, PYR and BaA could reach their maximum as approximately 99.0%, 67.5% and 89.5%, respectively, under the condition as follows: reaction time 30, 60 and 120 min, the concentration of ClO2 0.1, 0.4 and 0.5 mmol·L-1, and pH 7.2. ANTH was selected as the representative to study the reaction mechanism with ClO2. The oxidation products formed in the reaction of ANTH with ClO2 were tentatively identified by gas chromatography-mass spectrometry (GC-MS), and the results showed that the main product was 9, 10-anthraquinone, which could be biodegraded more easily and quickly than ANTH. Through analyzing the reaction properties of ANTH and ClO2, the possible pathway for the ANTH-ClO2 reaction was proposed based on the theory of single electron transfer (SET).     

Vanadium(Ⅳ)dimer complexes containing [V(o-C_6H_4OS)_3]~(2-)fragment and caged sodium ions

Tris[o-mercaptophenolato]vanadium(IV)dimer complexes(A)_2[V(mp)_3NaLL']_2(A=Ph_4P~+,H_2mp=o-mercaptophenol,L=MeCN,L'=EtOH,(1);L'=MeOH,(2))were prepared bythe reaction of anhydrous VCl_3 and Na_2mp in the molar ratio 1:3.Complex(3)(A=Et,N~+,L=L'=MeOH)was prepared by the reaction of VCl_3,Na_2mp and Li_2S in the molar ratio 1:2:1.The com-plexes were characterized by X-ray diffraction crystallography,infrared spectra,magnetic suseepti-bility,and cyclic voltammetric measurements.Complex 2 crystallizes in the triclinic space groupP1 with a=12.813(6),b=14.199(4),c=12.790(5),α=112.72(2),β=104.24(4).γ=88.68(4)°,V=2073.6,and Z=1.The structure was refined to R=0.058.Complex 3 crystallizes in the mono-clinic space group P2_1/n with a=12.359(3),b=17.452(6),c=14.829(13),β=96.51(5)°,V=3177.8,and Z=2.The final R factor is 0.067.Both of the anions of 2 and 3 contain two[V(rap)3]~(2-) fragmentslinked by sodium ions through the μ_3-O bridges with a crystallographic center of symmetry.The V(IV)atom is in a coordination environment intermediate between a trigonal prism and an ideal octahedron.     

STUDIES ON STEROIDAL PLANT-GROWTH REGULATORS (ⅩⅦ)——A NEW SYNTHESIS OF HOMOBRASSINOLIDE AND (22S,23S)-22,23-EPI-HOMOBRASSINOLIDE

Homobrassinolide (2) and (22S, 23S)-22,23-epi-homobrassinolide (4) were synthesized fromstigmasterol in seven steps respectively in 4.7% and 24.1% overall yields. The ratio of 2 to 4is 1:5. The key step is the highly regioselective formation of the B--homo-7-oxa-lactone ringby oxidation of an enol silyl ether with 3--chloro-peroxybenzoic acid.     

Propylene Dimerization by（η^5—C9H7）2 Nickel（Ⅱ）Catalytic System

The catalytic performance of Ni(η^5-Ind)2 complex in the dimerization of propylene was studied in combimation with an organoaluminum co-catalyst,eventually in the presence of a phosphine ligand.The effects of the type of aluminum co-catalyst and its relative amount,the nature of phosphine ligand and P/Ni ratio as well as the reaction temperature were examined.The results indicated that the nickel precatalyst exhibited high productivity for the propylene dimerization together with organoaluminum.It was likely to strongly modify the reactivity in the catalytic sytem when using phosphine ligand as additives,especially at the reaction temperature below 0℃.The catalytic system based on Ni(η^5-Ind)2 complex displaed an extremely high productivity(TOF up to 16900h^-1)and a good regioselectivity to 2,3-dimethylbutenes (2,3-DMB) in dimers(66.4%)under proper reaction parameters.     

Synthesis in solid state, structural regularity and reaction mechanism for [VS_4-Cu_n] clusters

The reaction system (NH4)3VS4/CuCl/PPh3/Et4NBr afforded a series of [VS4-Cun] dusters with various core configurations in the solid state at low heating temperature. The structural regularity of [VS4-Cun] dusters and the influence of the CuCl:(NH4)3VS4 ratio as well as that of reaction temperature and time on the formation of duster core have been summarized. The reaction mechanism of forming V-Cu-S clusters has also been explored.     

Two Amine-tethered Imidazolium NHC Ni(Ⅱ) Complexes: Synthesis,Structure and Catalytic Activity

Nickel(Ⅱ) complexes Ni(L1)2(1) and Ni(L2)2·CH3CN·H2O(2)(L1Cl = 2-(3-benzyl-2,3-dihydroimidazlo-1-yl)-N-(pyridin-2-yl)acetamide, chloride salt, L2Cl = 2-(3-naphthalene-2-ylmethyl)-2,3-dihydro-imidazlo-1-yl)-N-phenylacetamide, chloride salt) with amide-functionalized imidazolium NHC ligand were synthesized and determined by single-crystal X-ray diffraction. Complex 1 crystallizes in the monoclinic system, space group P21/c with a = 9.2561(19), b = 15.138(3), c = 20.750(4) , β = 90.216(3)°, V = 2907.3(10) 3 and Z = 4. Complex 2 crystallizes in the orthorhombic system, space group Pbca with a = 15.5469(16), b = 15.3521(15), c = 31.177(3) , V = 7441.2(13) 3 and Z = 8. They are stable in the air and formed via intermolecular weak interactions, including C–H···π contacts and C–H···O hydrogen bonds. Complex 1 was applied in Suzuki coupling reaction through the investigation of reaction conditions under the optimal choice conditions: 80 ℃, K3PO4, 3% mol catalysts, 6% mol PPh3 and toluene as solvent system could afford 96% yield in 5 h.     

Hydrothermal synthesis, structure and photocatalytic property of nano-TiO_2-MnO_2

TiCI4 and MnSO4.H2O as raw materials are hydrolyzed stiochiometrically, following the intermediate of oxide hydrating reacts at 150℃, 0.5 MPa in high-pressure reactor, after filtering, washing and drying, nanometric TiO2-MnO2 (Ti1-xMnxO2) is prepared. The effects of the reaction temperature and time on nanometric TiO2-MnO2 are also discussed. XRD shows that the product is TiO2-MnO2 with amorphous phase. After being sintered at above 780℃, it transfers into Ti1-xMnxO2 with a rutile structure. TEM shows that TiO2-MnO2 is the spherical particle. And the average diameter of the particles is 20 nm. The optical absorbance was determined by UV-265 spec-trophotometer after dispersing the sample in the mixture of water and glycerol with the ratio of 1 : 1 equably. It is found that the nano-material possesses the advantages of both nano-TiO2 and nano-MnO2, and it has strong absorption in the UV and visible region. Photodegradation of dyes in an aqueous solution is investigated using nanometricTiO2-MnO2 as a pho     

REACTIVITY OF METAL(O) DITHIOCARBAMATO CARBONYL COMPLEXES [Mo(CO)_4(S_2CNEt_2)]~- (M=Mo, W): SYNTHESIS AND STRUCTURE OF A NEW MIXED-VALENCE DINUCLEAR MOLYBDENUM-SULFUR COMPLEX, [Et_4N]_2[(CO)_4MoS_2MoS_2]

<正> The reaction of [Et4N][Mo(CO)4(S2CNEt2)] with tetraethylam-monium tetrathiomolybdate affords a new mixed-valence dinuclear molybdenum complex [Et4N]2[(CO)4MoS2MoS2] (1). 1 crystallizes in the orthorhombic space group Pbom with a = 18.403(2), b = 11.963(1), c= 13. 482(1)(?) , Z = 4, V = 2986(?)3, Dc=1. 55g/cm3, Mr = 6S2. 69. R =0. 042 and Rw =0. 057 for 1975 independent reflections with I≥3σ(I), F(000) = 1416, μ =11. 2cm-1. The structure of the anion of 1 consists of an octahedron for the lowvalent Mo atom and a tetrahedron for the high-valent Mo atom sharing an S - S edge. The Mo - Mo bond distance is 2. 992 (2) (?) and the bimetallic center MoS2Mo is planar with Mo-S of 2. 517 and 2. 231 A and MoSMo angles of 78. 04° and 77. 67°. The electron delocalization between the two Mo atoms with wide separated oxidation states is also discussed.     

SYNTHESIS AND CRYSTAL STRUCTURE OF [(η~5-C_5H_5)_2NdCl·OC_4H_8]_2

All attempts to prepare light lanthanide dicyclopeutadienyt chloride failed,due to the disproportionation reaction. The crystal complex of [(η~5-C_5H_5)_2NdCl.OC_4H_8]_2 was successfully prepared by the reaction of NdCl_3·2C_4H_8O with cyclopentadienyl sodium (molar ratio 1:1.8)in tetrahydrofuran at room temperatureThe composition of the title compound was determined by the methods of elemental analysis, infrared spectroscopy and photoelectron spectroscopy. The crystal structure of [(η~5-C_5H_5)_2NdCl·OC_4H_8]_2 was determined from single crystal X-ray diffraction. Data were collected at-60℃ under dry nitrogen atmosphere.The complex crystallizes in the monoclinic space group P2_1/c,with Z=2. Lattice parameters are: a=8.201(3), b=21.589(6),c=8.596(3),β=109.10(3)°.The structure was solved by Patterson and Fourier techniques and refined by least-squares to a final conventional R=0.0636 for 1680 reflections. There are two Nd atoms in the dimeric unit which are bridged asymmetrically by the two chlori     

Kinetic Studies on the Reaction of Sodium Hexa-cyanoferrate(II) Complex with Peroxydisulfate Anion

Introduction In the previous studies on the oxidation reaction,peroxydisulfate was widely used as an oxidizingagent.1-5 One of the advantages of this oxidant lies in itsstability in a wide range of pH values. The reaction be-tween Fe(CN)5L3- (L=N-aromatic heterocyclic li-gands) and S2O8 2- has been proved to proceed throughan outer-sphere electron transfer mechanism.5 For a re-action [(Eq. (1)] to be under an outer-sphere mechanismthe steps involved are the formation of a reactant …     

Mechanism and origin of diastereoselectivity of N-heterocyclic carbene-catalyzed cross-benzoin reaction: A DFT study

Herein,the origin of the diastereoselectivity of N-heterocyclic carbene(NHC)-catalyzed cross-benzoin reactions between an a-amino aldehyde and furfural was studied by density functional theory.The computational results showed that the reaction proceeded through four steps:nucleophilic addition of NHC onto furfural,formation of a Breslow intermediate,cross-coupling reaction between Breslow intermediate and a-amino alde hyde,and dissociation of the catalyst.The cross-coupling was identified as the diaste reoselectivity-determining step,with the R-configured product generated preferentially.Noncovalent inte raction(NCI)analysis showed that the C-H…O and C-H…F inte ractions were responsible for determining the diastereoselectivity.     

A new oxidovanadium(Ⅳ) Schiff base complex containing asymmetric tetradentate ONN0O0Schiff base ligand:Synthesis,characterization,crystal structure determination,thermal study and catalytic activity

After synthesis of an asymmetric tetradentate ONN0O0 Schiff base ligand(H2L) followed by reaction of the synthesized H2 L with an equimolar mixture of methanolic solutions of the VO(acac)2, a new oxidovanadium(IV) Schiff base complex(VOL) was synthesized. The Schiff base ligand and its complex were characterized by FT-IR and UV–vis spectra and C, H, N analysis. The crystal structure of VOL was also determined by single crystal X-ray analysis. The VOL complex crystallizes in monoclinic space group Cc. The Schiff base ligand acts as a tetradentate ligand through its two iminic nitrogens and two phenolic and acetylacetonate oxygens. Thermogravimetric analysis of the VOL showed that it decomposes in two steps and converts to mixed vanadium oxides at 477 8C. In addition, thermal decomposition of the VOL complex in air at 660 8C leads to formation of V2O5 nanoparticles with the average size estimated from XRD 49 nm. The catalytic activity of the VOL complex was investigated in the epoxidation reaction and different reaction parameters were optimized. The results showed that the cyclic alkenes were efficiently converted to the corresponding epoxides, whereas the VOL did not appreciably convert the linear alkenes.     

Synthesis,crystal structures and spectral properties of cobalt (Ⅱ) complexes:[ CoL (N_3) ] ·ClO_4 and CoL (N_3)_2 [L=tris ((3,5-dimethylpyrazol-1-yl) methyl) amine

Two monomeric cobalt(Ⅱ)complexes,[CoL(N3)] ClO4(1)and CoL(N3)2(2),where L is tris((3,5-dimethylpyrazol-1-yl)methyl)amine,were synthesized and their crystal structures were determined by X-ray diffraction technique.Complex 1 is five coordinated with one azide nitrogen atom and four nitrogen atoms of the tris((3,5-dimethylpyrazol-l-yl)-methyl)amine ligand,and the metal center is in distorted trigonal bipyramidal environment.Complex 2 is six coordinated distorted octahedron with the two azide nitrogen atoms and four nitrogen donors of the tris((3,5-dimethylpyrazol-1-yl)-methyl)amine ligand.The solution behaviors of the title complexes have been further investigated by UV-Vis,and 1H NMR analysis.It is found that the formation of 1 and 2 depends on the molar ratio of the azide ion to metal salt and ligand Complex 1 attached with one azide group is more stable and easy to generate than complex 2 incorporated with two azide groups,and the reasons were well discussed.     

Synthesis,Characterization and Antibacterial Activities Study of a Pharmaceutical Cocrystal of Artesunate and 4,4’-Bipyridine

We report here a cocrystal with artesunate as the active pharmaceutical ingredient(API) and a pharmaceutical intermediate 4,4?-bipyridine as the cocrystal former(CCF). The analysis of single-crystal X-ray diffraction demonstrates that the eutectic structural unit consists of two artesunate molecules and one 4,4?-bipyridine molecule with their ratio to be 2:1. The carboxyl group on artesunate acts as a donor, and the acceptor is N on 4,4?-bipyridine, forming an O–H···N hydrogen bond. The appearance of new diffraction peaks in the X-ray powder diffraction pattern also indicates the formation of new phases. The PXRD results indicated a pure phase for the synthesized sample. The cocrystal is slightly soluble in water. Antimicrobial activities showed that the cocrystal displayed effective inhibition of different bacteria.     

Study on the alkylation reaction of guanine and N-acetylguanine and the synthesis of 1''''-C alkylated carba-DHPG analogues

The alkylation reaction of guanine and N-acetylguanine with model compounds such as isopropyl bromide or 4-heptyl tosylate were studied. The reaction conditions such as temperature, solvent, base, and catalyst were examined for their effects on the reaction rate, and the yield and regioselectivity of the coupling reaction. The highest yield was obtained by using DMSO as the solvent. The reaction proceeded in a homogenous manner to give higher yield of 9-N and 7-N substituted product in a mole ratio of 1:1. The ratio could be raised to 2:1 if dibenzo-18-crown-6 was used as a catalyst. Using the above procedure, three carba-DHPG analogues bearing different 1'-C alkyl side chains were synthesized.     

THE SYNTHESIS AND CRYSTAL STRUCTURE OF A NOVEL TETRANUCLEAR COPPER (Ⅰ) CLUSTER COMPLEX, Cu_4(α-C_(10)H_7CSS_2)_4·1/2CS_2

The title compound has been synthesized by the reaction of sodium α-dithionaphthoatewith CuCl_2 in an alkaline aqueous solution or by the reaction of α-dithionaphthoic acid withCuCl_2 in an organic solvent, The crude product was recrystallized in a mixture of CS_2 andC_2H_5OH. The crystals obtained are red and stable in air. The structure of the title compound is determined by a single-crystal X-ray diffractionanalysis. The crystal belongs to monoclinic space group C_(2h)~5- P(2_1/a) with unit cell parameters:a= 16.453(3)A, b=12.651(4)A, c=23.182(7)A, β=100.5(2)°, V=4744.6A~3,Z=4. Thestructure was refined to R=0.06 for 4707 reflections. In the molecule, Cu_4 cluster has a distorted tetrahedral configuration. Surrounding thistetrahydron are four α-perthionaphthoate ligands, coordinated to copper through the sulfuratoms. One of the sulfur atoms in each ligand forms sulfur bridge with copper atoms,while the other is coordinated to only one copper. The three Cu--S bonds formed by thethree sulfur atoms with a given copper atom are approximately coplanar. Each group--C--S_2 with Cu atom on a vertex of the tetetrahedron forms a five-member ring. Thesefive-member rings are also approximately cooplanar. The molecule possesses an approachingS_4 point symmetry. The mechanism for the formation of the title compound involves a redox reaction.which is discussed in this paper.     

Catalytic Systems Containing p-Toluenesulfonic Acid for the Coupling Reaction of Formaldehyde and Methyl Formate

The coupling reaction of formaldehyde(FA)and methyl formate(MF)to form methyl glycolate(MG)and methyl methoxy acetate(MMAc),catalyzed by p-toluenesulfonic acid(p-TsOH)as well as assisted by different kinds of solvents or Ni-containing compounds,had been investigated.The results showed that when the reaction was carried out at 140℃,with a molar ratio of FA to MF of 0.65:1, molar fraction of p-TsOH to total feedstock of 11.0%,and reaction time of 3 h,the yield of MG and MMAc was 31.1% and 17.1%,respectively,p-TsOH catalyzed the coupling reaction by means of the synergistic catalysis of protonic acidity and soft basicity.Adding extra solvents to the reaction system was unfavorable for the reaction.The composite catalytic system consisting of p-TsOH and NiX_2(X=Cl,Br,I)exhibited a high catalytic performance for the coupling reaction,and NiX_2 acted as a promoter in the reaction,whose promotion for the catalysis increased in the following order:NiCl_2相似文献   

Synthesis and Structure of a Novel Cobalt(Ⅱ)Complex with the Tertiary Carbinol Derivative of Di-4-pyridinylmethanone

The title complex [Co[(4-C5H4N)2C(OH)(NHC3H7)]2(NO3)2]∞ was obtained and characterized through elemental analysis, FT-IR and X-ray crystallography. The complex crystallizes in space group P3(2)21 with a=10.2480(11), b=10.2480(11), c=26.943(6), β=120.00°, [Co[(4-C5H4N)2C(OH)(NHC3H7)]2(NO3)2]∞, C28H34CoN8O8 , Mr=669.56, Z=3, V=2450.5(7)3 , Dc=1.361 g·cm-3 , μ=0.584 mm-1 , F(000)=1047, R=0.0498 and wR=0.1301. The Co(Ⅱ) center exhibits a N4O2-octahedral coordination geometry surrounded by a pair of nitrates at the axial positions and four pyridyl N atoms at the equatorial sites. An infinite double-bridged chain structure with μ2-bridging (4-C5H4N)2C(OH)(NHC3H7) ligands is formed, which is the in situ product of metal-promoted nucleophilic addition reaction of propan-1-amine with di-4-pyridinylmethanone ((4-C5H4N)2CO) in the presence of Co(NO3)2·6H2O. It is the first tertiary carbinol metal complex derived from di-4-pyridinylmethanone so far, and also the rare example of tertiary carbinol derivative of dipyridylmethanone family. The nucleophilic reaction at the carbonyl of dipyridylmethanone in the presence of metal salt will be discussed.     

三元配合物RE [(Pdtc)3(phen)]热化学性质的规律性

Treatment of hydrate rare-earth(RE=La,Pr,Nd,Sm-Lu)chloride with ammonium pyrrolidinyldithiocarboxy-late(apdtc)and 1,10-phenanthroline(phen)gave rise to thirteen complexes with an empirical formulaRE[(pdtc)_3(phen)].The enthalpies of solution of hydrate rare-earth(RE= Sm-Ho,Tm-Lu)chloride,apdtc and phenin ethanol were measured by an RD-496 Ⅲ microcalorimeter at 298.15 K,along with the mixing enthalpy of etha-nol solution of APDC and that of phen and the enthalpies of reaction of formation of the title complexes in ethanol.The enthalpies of reaction of formation of the title complexes in solid were available through a rationally thermo-chemical cycle.Using an RD-496 Ⅲ microcalorimeter,a model was developed for calculating the specific heat ca-pacity and the responding specific heat capacity of the complexes were determined.The thermochemical properties,including the enthalpies of solution of hydrate rare earth chloride in ethanol,the enthalpies of reaction of formationof the title complexes in ethanol,the enthalpies of reaction of formation of the title complexes in solid,the specialheat capacities at room temperature,the standard molar enthalpies of combustion and the standard molar enthalpiesof formation for this series of complexes versus the atomic numbers of rare earth,presented triplet effect,which isrepresentative of certain covalent bond between RE and the ligands and the result of 4f electron not shielded fullyby 5s5p.