Electronic and Optical Properties of Monoclinic and Rhombohedral Vanadium Sesquioxide

The electronic and optical properties of monoclinic and rhombohedral V2O3 are investigated in the framework of density functional theory (DFT) and GGA+U. It is found that, the metal-insulator transition (MIT) in V2O3 is induced by the on-site correlation effect, accompanied with a distinct orbital occupation change. The MIT is independent of the structural transition. The theoretical energy gap 0.6 eV agrees with the experimental value of 0.66±0.05 eV very well. Subsequently, the optical properties are also investigated. Interestingly, the insulating V2O3 shows minimal absorption in the infrared region, but the metallic V2O3 becomes opaque in such region. Therefore, a threshold at about 1 eV interprets the experimental charge gap (Perucchi et al., 2009) theoretically. Such infrared thermochromism makes it a potential candidate for several optical applications.     

Kinetic study on the ligand exchange reactions between bis(alkylxanthato)palladium(II)and bis(N,N-dialkyldithiocarbamato)palladium(II)by high-performance liquid chromatography

The rate constants and equilibrium constants of ligand exchange reactions between his(alkylxanthato)palladium(Ⅱ),Pd(S_2COR)_2(R=Am,n-Hex,Bz),and bis(N,N-dialkyldithiocarbamato)palladium(Ⅱ),Pd(S_2CNR_2)_2(K=Et,n-Pr,n-Bu),in chloroform solution have been determined ina temperature range of 20—50°C by means of high-performance liquid chromatography.It was foundthat both the forward and reverse reactions are of second order.All of the equilibrium constants Kdetermined are 10.3±1.0,much greater than the value(K=4)calculated statistically which indicatesthat the ternary complexes are more stable than the binary complexes.The experimental resultsrevealed that the reaction rate decreases with the increase in the size of R and R~1 groups and the latterare more remarkable,consistent with the deduction of steric effect.The activation parameters ofthe reactions have been calculated.In reaction series(11)and(12)(in the text)the isokinetic tempera-tures B=390±8K and β=346±15 K have been observed respectively.A plausiblemechanism in-volving an eight-membered ring intermediate has been proposed on the basis of experimental results.     

Effects of retrograde-zoning of garnet on Sm-Nd isotopic dating of eclogite and oxygen isotopic disequilibrium between eclogitic minerals

The compositional zoning of the garnet in a strongly deformed eclogite from Raobazhaifoliated peridotite has been recognized. The CaO concentrations of the garnet are decreased fromthe core to the rim, while its MnO concentrations are increased, suggesting the retrograde origin ofsuch CaO-MnO zoning. The tie line of garnet+omphacite from this eclogite gives a Sm-Nd ageof (187±5) Ma, which is less significant than the Sm-Nd ages of (221±5)-(228±3) Ma and (210±6)-(214±6) Ma for ultrahigh-pressure eclogites in the southern Dabie zone and in the northernDabie zone, respectively. This younger Sm-Nd age could result from the ~(143)Nd/~(144)Nd ratio decreaseof the retrograde zone in the garnet. The δ~(80)O values of the garnet and omphacite show that theirfractionation values are less than the equilibrium fractionation value between the garnet and om-phacite at 500-900℃, which suggests an oxygen isotopic disequilibrium between them.     

Vibronic spectra of the allyl radical at 6-8 eV with resonance-enhanced multiphoton ionization technique

The allyl radical was produced in molecular beam by pyrolysis of allyl iodide. The vi-bronic spectra from ground state to six new electronic states of the allyl radical at 6-8 eV, π→3dxz, π→3dxy, and π→ns (n=4, 6, 7, 8) were observed firstly with the aid of time-of-flight mass spectros-copy and resonance-enhanced multiphoton ionization technique. Vibrational progression of v7 (C3 bend) with gross spacing of about 430 cm-1 was observed in ns Rydberg states. The adiabatic ionization potential of the allyl radical was obtained to be (65641 ± 20) cm-1 ((8.138± 0.002) eV) by fitting the term values of ns (n=4,6,7,8) Rydberg states with Rydberg formula.     

CRYSTAL STRUCTURE INVESTIGATION OF VANADYL COMPLEXES OF TRIDENTATE LIGAND (Ⅱ)——SYNTHESE AND CRYSTAL STRUCTURE OF 1-(2-PYRIDYLAZO)-2-NAPHTHOLATO-DIOXOVANADIUM (Ⅴ) DIMER [VO_2(C_(15)H_(10)N_3O)]_2(H_2O_2)(CHCl_3)_2 AND PYRIDINE-(1-(2-PYRIDYLAZO)-2-NAPH

The title complexes crystallize in space groups C(?)-P(?) and C_(2h)~5-P2_1/c, and with unit cell parameters a=8.488. b=10.100, c=11.974. α=72.73°, β=78.56°, γ=73.55°, and a=11.496, b=9.883. c=16.360, β=100.18°, respectively. All the V coordinates are obtained from Patterson and direct methods, respectively, and then Fourier and difference Fourier methods are employed to deduce other non-hydrogen atoms. Structural parameters are refined with least-squares technic, yielding final discrepancy factors R=0.081 and 0.067, respectively. Structural analyses demonstrate that the dimer of VO_2~+ complex is formed through the sixth-position bonding of a bridge oxygen atom of one VO_2~+ group with another VO_2~+, and the formation of VO(O_2)(C_(15)H_(10)N_3O)(C_5H_5N) shows that VO~(2+) complex with strong chelating tridentate PAN-seems less difficult to transform into the pentagonal bipyramid VO~(3+) complex. Since no peroxo species has been used in the synthesis, the fact that a peroxo group forms in the     

ELECTRONIC ENERGY BAND STRUCTURE OF MOLECULAR CRYSTALS MCI·(TCNQ)_2 AND ITS RELATIONSHIP WITH THE ELECTRICAL CONDUCTION

The structure of electronic energy bands, electric charge distribution and the amount of charge transfer of molecular crystals 1-MCI·(TCNQ)_2 (Ⅰ) and 2-MCI· (TCNQ)_2 (Ⅱ) have been studied. The results are: (ⅰ) The dominant contributions to the electrical conductivities for crystals Ⅰ and Ⅱ are from TCNQ molecular columns, and the charge carriers are electrons. (ⅱ) The electrical conduction is mainly due to the hopping of charge carriers between the seats of lattice. (ⅲ) The considerable difference of the electrical conductivities between crystals Ⅰ and Ⅱ is due to the differences between (a) the concentrations of charge carriers n_(AⅠ)~C= 0.9988-|e|/cell and n_(AⅡ)~C=0.0340-|e|/cell; (b) the widths of the energy bands △E_(AⅠ)~(LU)=0.88 eV and △E_(AⅡ)~LU=0.040 eV; (c) the first derivative of E with respect to k, (dE/dk)_(K_FAⅠ)~(LU)=0.27 eV· and (dE/dk)_(K_FAⅡ)~LU=0.0048 eV·; and (d) the difference of energy barriers for the hopping of charge carriers ∈_Ⅱ-∈Ⅰ=2.5-8.8 kJ/mol.     

Theoretical Study on the Structural and Electronic Properties of Thiocarbamide Hydrochloride

In the present paper, the electronic band structure, density of states （DOS）, and projected density of states （PDOS） analysis of thiocarbamide hydrochloride are reported. Calculations of the electronic properties have been carried out on the basis of fully self-consistent pseudopotential method using DFT. The results show that near the Fermi level, more prominent densities of states are seen between -8 eV and -6 eV in the valence band mainly due to the Cl-3p, N-2p and S-3p orbitals.     

Quantum Chemical Study of CnAl2^± （n=1～10） Clusters： Structure and Stability

Geometries, electronic structures and vibrational frequencies of CnAl2± clusters have been investigated by using the B3LYP-DFT method in the range of n = 1～10. At the B3LYP/6-311G level, the ground state structures of CnAl2± clusters are planar or linear with terminal aluminum atom. In these structures, the C–C bonds are alternately changed between double and triple. The changing magnitude of the averaged bond length decreases with the increase of cluster size. The energetic analysis showed that CnAl2± clusters with even n are more stable than those with odd n.     

Density Functional Theory Investigation on the Reaction Mechanisms of Ti(~3F) with CH_2Cl_2 and CHCl_3 to CH_2=TiCl_2 and HC÷TiCl_3

The reaction mechanisms of Ti(~3F) + CH_2C1_2→CH_2=TiCl_2 and Ti(~3F) + CHC1_3→HC÷TiCl_3 were investigated with Gaussian 03 program package at the B3PW91/6-311++G(d,p)level.The computational results revealed that:1) Both reaction systems are initiated by Ti(~3F) atom attacking the C atom of CH_2C1_2 and CHCl_3 to activate a C-Cl bond;2) Both reaction systems were carried out via triplet reaction channels;3) CH_2=TiCl_2 has singlet and triplet isomers,and the singlet one is more stable;4) The HOMO of CH_2=TiCl_2(S) illustrates a π-bonding interaction between C and Ti;5) Only singlet HC÷TiCl_3 was located,and the Mulliken atomic spin densities show that the two single electrons are mostly on the C atom.     

MULTIDENTATE LIGAND EXCHANGE KINETICS:REACTIONS OF AMINOCARBOXYLATO-FERRATE(Ⅲ) COMPLEXES WITH 4-(2-PYRIDYLAZO) RESORCINOL

The kinetics and mechanism of ligand substitution reactions of nitnlotriacetatoiron(Ⅲ),(Fe(NTA)],and N-(2-hydroxycthyl)-ethylencdiaminetriacetatoiron(Ⅲ),[Fe(HEDTA)],complexes with 4-(2-pyridylazo) resorcinol (Par) has been investigated at pH=9.0±0.02,I=0.1mol·l^-1 (NaClO₄,and temp.=25±0.1℃ and 30±0.1℃ respectively. The reaction has been studied spectrophotometrically at 496 nm. (λmax of Fe(Par)₂. In both reactions the final product was [Fe(Par)₂]^-. The values of second order rate constants for NTA and HEDTA exchange reactions are (10.0±0.8)×10¹¹·mol^-1·s^-1 and (2.7±0.1)×10^-1·mol^-1·s_-1 respectively. The reactions of NTA and HEDTA exchange were studied in the pH range 6-9.5 and 7-10.85 respectively. The rate of reacton of [Fe(NTA)] with HPar^- first increases with pH and then levels off. However,in the case of [Fe(HEDTA)] reaction,the rate increases monotonically with increase of pH in the specified range.     

Layered Lanthanum Complex with 3-Nitrophthalic Acid Assembled via Hydrogen Bonds-Synthesis, Structure and Characterization of [LaL(HL)(H_2O)_3]_2·2H_2O (H_2L=3-NO_2C_6H_3(CO_2H)_2)

A new dinuclear centrosymmetric complex [LaL(HL)(H2O)3]2·2H2O (H2L = 3-nitro- phthalic acid, NPA) was synthesized in water/ethanol solution and characterized by X-ray diffraction, IR spectrum and TGA-DTA. The complex crystallizes in triclinic system, space group P1 with a = 8.1549(16), b = 8.8856(18), c = 15.277(3) , α = 100.93(3), β = 90.81(3), γ = 104.56(3)°, V = 1049.8(4) 3, Z = 1, μ = 2.125 mm-1, Dc = 1.994 g/cm3, R = 0.0259 and wR = 0.0679. Two 3-nitrophthalates(2-) coordinate with the La3+ ions in a bridging mode, and two monohydrogen- 3-nitrophthates(1-) and three waters in terminal ways, respectively. Each La3+ ion is nine- coordinated to exhibit a distorted tricapped trigonal prism coordination polyhedron. Both the coordinated and crystal waters are involved in the inter- and intramolecular hydrogen bonds. The dinuclear units are linked into a 2D network structure in the ab plane via intermolecular hydrogen bonds along the axes a and b. Two crystal waters fill each rhombic pore of the network. The networks are further packed along the c axis forming a layered supramolecular structure through the C–H…O weak forces between the adjacent sheets. TGA analysis shows the complex undergoes the loss of waters of crystallization and coordination and the decomposition of ligands sequentially.     

SYNTHESIS AND PROPERTIES OF ANILING ANILING AND 0-AMINOBENZENESULFONIC ACID COPOLYMER*

Poly(aniline- co-o-aminobenzenesulfonic acid) (PAOABSA) as a water soluble conducting polymerwas synthesized by chemical polymerization. The productivity and the room-temperature conductivity of thecopolymer were measured as a function of the reaction conditions, such as reaction temperature, the ratio ofoxidant to monomer and the degree of sulfonation defined as the ratio of sulfur to nitrogen atoms(S/N). Themain results obtained are summarized as follows : (1) lower reaction temperature (at about 0℃) is favorablefor the enhancement of the room-temperature conductivity of the copolymer; (2) higher content of oxidant isunfavorable for increasing the room-temperature conductivity of the copolymer; (3) both productivity androom-temperature conductivity of the copolymer decrease with increase of the degree of sulfonation whichwas always lower than 0.5 even an excess of o-aminobenzenesulfonic acid was added, probably because thereactivity ratio of aniline (γ=2.99± 0.05) is much higher than that of o-aminobenzenesulfonic acid (γ_2 = 0.06±0.02) estimated by using Fineman-Ross method and least square method.     

CRYSTAL STRUCTURE OF THE ADDUCT OF DECAVANADATE AND HEXAMETHYLENE-TETRAMINE {[HMT· H~+(V_(10)O_(28))~(6-)·H~+·HMT]· 2[HMT· CH_2NH_2]~+·2(H_3~+O)·12H~2O}

The title compound crystal belongs to the trilinic space group C_i~1—P(?) with unit cell parameters: a=11.208 (4), b=13.166 (4), c=13.239 (3),α=118.15 (2)°,β=94.78(2)°,γ=109.19 (2)°, and Z=1. The crystal structure was solved by direct method and difference Fourier techniques using the SHELXTL program, and was refined finally to R=R_W=0.0462 for 4702 reflections. Structural analysis shows that the four protons in the cluster of the decavanadate group are separated into two types. For one of them, the two protons are captured by two O7 in the cluster of the decavanadate and two nitrogen atoms of the hexamethylenetetramine, to form hydrogen bonds; moreover, we have verified that the N-aminomethylhexamethylenetetraminium which was produced during the reaction existed in the title compound crystal. We infer that the N-aminomethylhexamethylenetetraminium [(CH_2)_6N_4CH_2NH_2]~+ could be produced by the heterogeneous catalysis reaction from the surface of the vanadium pentoxide [V_2O_5].     

MOLECULAR STRUCTURES AND SINGLE CRYSTAL ESR SPECTRA OF IMIDAZO-LATE-BRIDGED Co(Ⅲ)-Cu(Ⅱ)-Co(Ⅲ)AND Co(Ⅲ)-Zn(Ⅲ)-Co(Ⅲ) COMPLEXES

The structures of the heterotrinuclear complexes, [(NH_3)_5ColmCu(dien)ImCo(NH_3)_5]-(C10_4)_6·4H_20 and [(NH_3)_5CoImZn(dien)ImCo(NH_3)_5]-(ClO_4)_6·4H_2O, are reported. Co--Cu--Cocrystallizes in the monoclinic space group C2/c with a =32.414(4), b= 9.421(1), c=15.167(5)?,β= 90.91(2)°, Z=4 and Co--Zn--Co in the same space group with a = 32.578(2), b = 9.419(1), c = 15.125(3)?, β=91.10(1)°Z=4. The Cu(Ⅱ) and Zn(Ⅱ) geometriesare intermediate between a trigonal bipyramid and a square pyramid,the Co(Ⅲ) is a-hexagonal coordination and the dien ligand shows a disordered contribution in the respectivestructure.The magnetic properties of Co--Cu--Co are investigated. From the single crystalESR spectra studies, the anisotropic g and A tensors and electronic spin-density of Co--Cu--Co are obtained and the nature of the bonding for Cu~(2+) is discussed.     

Li~+,Na~+//+ Cl~-,B_4O_7~(2-)-H_2O Reciprocal Quaternary System Solubility Phase Diagrams

The solubilities, refraction indices and densities of saturated solution of Li+ , Na+ Cl- ,B4O72- -H2O reciprocal quaternary system at 0℃, 25℃ and 50℃ were determined by using isotherm method. Using total concentration of all the salts in solution as concentration coordinate(ordinate) the isothermal stereogram of solubility of the system was drawn. The results showed that the stable salt-pair of the system is Na2Cl2-Li2B4O7 and that there are two isothermal invariant points, eutonic ponit E and inversion point Pcorresponding to the eqilbria: solution (E) LiCl·H2O (at 25, 50℃) or LiCl·2H2O (at 0℃) + NaCl + Li2B4O7 · 3H2O and solution (P) + Na2-B4O7·1OH2O NaCl + Li2B4O7·3H2O and the crystallization fields ofborates are much larger than those of chlorides.     

Adsorption and dissociation of H2O on Cu2O(100):A computational study

The adsorption and dissociation of water on Cu2O(100) have been investigated by the density functional theory-generalized gradient approximation (DFT-GGA) method. The corresponding reaction energies, the structures of the transition states and the activation energies were determined. Calculations with and without dipole correction were both studied to get an understanding of the effect of the dipole moment on the adsorption and reaction of water on dipole surface Cu2O(100). When dipole correction was added, the adsorption energies of H2O on different sites generally decreased. The calculated activation barriers for HxO (x = 1, 2) dehydrogenation are 0.42 eV (1.01 eV without the dipole correction) and 1.86 eV, respectively, including the zero point energy correction. The first dehydrogenation outcome is energetically the most stable product.     

CRYSTAL STRUCTURE OF {Mo_3(μ_3-S)(μ-S)_3 [S_2P(OEt}_2]_4·PhCH_2CN}

<正> Mr=2548.12, Triclinic, P1, a=15.941(5), b=15.957(2),c=20.240(6)A, α=76.41(2),β=83.87(2),γ=74.41(2)°,V=4814.6A3, Z=4, Dc=1.757g.cm-3, Final R=0.053 for 11867 reflections. There are two crystallographically independent M1 type trinuclear Mo cluster molecules with 'loose coordination site', A and B, in an asymmetric unit of the title crystal. They are formulated as {Mo3S4(u-dtp)(dtp)3.PhCH2CN}(dtp=[S2P(OEt)2]-) and have essentially identical cluster molecular configuration, but differ from each other in the conformations for the phenyl rings of the ligands PhCH2CN. The lengths of the Mo-Mo bonds are 2.750(1), 2.753(1),and 2.768(1)A for molecule A and 2.742(1), 2.756(1), and 2.764(1)A for molecule B, while the dihedral angles betweem the phenyl ring and the {Mo3} triangle are 25.0° and 94.9° for A and B respectively.     

Study on the Biomimetic Oxidation Catalyzed by the Model Compound of Cytochrome P-450(VI)——The Influence of Substituent x in T(x-p)PMn(Ⅲ)Cl on the Hydroxylation of Alkane

The influence of monosubstitution at phonyl rings in a series of T(x-P) PMn (Ⅲ)Cl (x = o , m , p-CH3, CH3O, Cl, Br, I, NO , o-NH2, p-(CH3)3C) on the biomimetic catalytic hydroxylation and chlorizaiton of cyclohexane with PhIO was studied. The yields of cyclohexanol and chlorocyclohexane increased with the electron-withdrawing ability of the substituent in this manganese complex. The fair linear correlations between the yields of cyclohexanol and para or ortho substituent constant are presented as:logYx/YH = 0.310p+0.03, logyx/YCH3 = 0.61σ0.07Es+0.05, But there are no linear correlations between the yields of chloro-cyclohexane and either para, ortho or meta substituent constants.     

Y-Ba-Cu-O mixed oxides for production of diphenols in liquid-solid phase

Superconductor mixed oxides were often used as catalysts at higher temperature in gas phase oxidations, and considered not suitable for lower temperature reactions in the liquid-solid phase; here the catalysis of YBa2Cu3O7+x and Y2BaCuO5+x in the phenol hydroxylation at lower temperature with H2O2 as oxygen donor was studied, and found that the superconductor YBaCu3O7±x has no catalytic activity for phenol hydroxylation, but Y2BaCuO5±x does, even has better catalytic activity and stability than most previously reported ones. With the studies of catalysis of other simple metal oxides and perovskite-like mixed oxides, a radical substitution mechanism is proposed and the experimental facts are explained clearly, and draw a conclusion that the perovskite-like mixed oxides with (AO)(ABO3) and (AO)2(ABO3) structure have better catalytic activity than the simple per-ovskite oxides with (ABO3)3 structure alone, and (AO) structure unit is the key for the mixed oxides to have the phenol hydroxylation activity.     

Kinetic model of induced codeposition of Ni-Mo alloys

The kinetic model of induced codeposition of nickel-molybdenum alloys from ammoniun citrate solution was studied on rotating disk electrodes to predict the behavior of the electrode-position. The molybdate (MoO42-) could be firstly electro-chemically reduced to MoO2, and subsequently undergoes a chemical reduction with atomic hydrogen previously adsorbed on the inducing metal nickel to form molybdenum in alloys. The kinetic equations were derived, and the kinetic parameters were obtained from a comparison of experimental results and the kinetic equations. The electrochemical rate constants for discharge of nickel, molybdenum and water could been expressed as k1(E) = 1. 23 × 109 CNi exp( - 0.198FE/RT) mol/(dm2·s), k2(E) =3.28× 10-10 CMoexp( - 0. 208FE/ RT) mol/(dm2·s) and k3(E) = 1.27 × 10-6exp( - 0.062FE/ RT) mol/(dm2 · s), where CNi and CMo are the concentrations of the nickel ion and molybdate, respectively, and E is the applied potential vs. saturated calomel electrode (SCE). The codeposition p