Superoxide Complex [W4O12（O2^-）]： A Theoretical Study

Extensive DFT calculations are performed to optimize the geometric structures of O-rich tungsten oxide clusters, to simulate the PES spectra, and to analyze the chemical bonding. The ground-state structure of W4O14^- is best considered as W4O12（O2^-）, containing a side-on bound superoxide ligand. The current study indicates that the extra electron in W4O12^- is capable of activating dioxygen by non-dissociative electron transfer （W 5d → O2 π^＊）, and the anionic clusters can be viewed as models for reduced defect sites on tungsten oxide surfaces for the chemisorption of O2.     

Synthesis and characterization of a new Mo-Fe-S cluster compound containing MoO_3S_3 unit and mixed-valent Mo atoms [Et_4N]_2[Mo_2Fe(CO)_4(S,O-C_6H_4-1,2)_3Cl_2]

Reaction of [Mo3(CO)7(S,O-C6H4-1,2)3]2- with FeCl2 in MeCN at 60℃ affords a new Mo-Fe-S cluster complex containing MoO3S3 unit and mixed-valeut Mo atoms, [Et4N]2[Mo2Fe-(CO)4(O,S-C6H4-1,2)aCl2] (1). 1 is characterized by elemental analysis, IR, Mossbauer spectra, X-ray photoelectron spectra and mass spectra. And the structure of 1 is suggested as the structure which contains a [Mo(S,O-C6H4-1,2)3] unit of which the two of three sulfur atoms link to a Mo(CO)4-moiety and the three oxygen atoms are coordinated to a FeCl2 ligand.     

NORMAL COORDINATE ANALYSIS OF DINUCLEAR MOLYBDENUM COMPLEX UNIT Mo_2O_2(μ-S)_2(dtcR_2)_2

<正> INTRODUCTION. The empirical assignments of vibrational spectra of Mo_2O_2(u-S)_2(dtcR_2)_2 have been reported. It is necessary to assign the spectra by theoretical calculation for better understanding molecular structureand chemical bonding of the complexes. We report normal analysis of thetitle unit in this paper.     

Synthesis, Structure and Properties of (n-Bu_4N)_3[Mo_6O_18NNAr(NO_2)_2]

The title compound was synthesized and characterized by means of elemental analysis, IR, DTA-TG and UV. Its single crystal structure was solved by using direct methods. The compound crystallizes in the orthorhombic space group Pmc(?) with lattice parameters: a = 1. 7261(2), b=l. 7537(3), c=2. 4258(3) nm. V=7. 34220 nm3, F(000) = 3648, Z = 4. The structure was refined to conventional discrepancy factors of R=0. 060 for 3176 observed reflections [Ⅰ>3σ/(Ⅰ)]. The anion represents a modification of the well-known [Mo6O19]2- anion, in which a single terminal oxo group is replaced by a 2,4-dinitrophenyl hydrazine ligand while the structure integrity of the hexanuclear framework is maintained.     

A NORMAL COORDINATE ANALYSIS OF [MoFe_2S_4Cl_4]~(2-) DIANION

<正> INTRODUCTION. On the basis of the 'Reactive Fragment Rypothesis' proposed by Prof. Lu Jiaxi in 1981 for the active center of the nitrogenase, the IR spectra of some linear Mo-Fe-S clusters so-called 'fragment' compounds, have been studied and the empirical assignments have been made     

IR and Raman Vibrational Assignments for Metal-free Phthalocyanine from Density Functional B3LYP／6-31G（d） Method

Vibrational (IR and Raman) spectra for the metal-free phthalocyanine (H2Pc) have been comparatively investigated through experimental and theoretical methods. The frequencies and intensities were calculated at density functional B3LYP level using the 6-3 IG(d) basis set. The calculated vibrational frequencies were scaled by the factor 0.9613 and compared with the experimental result. In the IR spectrum, the characteristic IR band at 1008.cm^-1 is interpreted as C-N (pyrrole) in-plane bending vibration, in contrast with the traditional assigned N-H in-plane or out-of-plane bending vibration. The band at 874 cm^-1 is attributed to the isoindole deformation and aza vibration. In the Raman spectrum, the bands at 540, 566, 1310, 1340, 1425, 1448 and 1618 cm^-1 are also re-interpreted. Assignments of vibrational bands in the IR and Raman spectra are given based on density functional calculations for the first time. The present work provides valuable information to the traditional empirical assignment and will be helpful for further investigation of the vibration spectra of phthalocyanine analogues and their metal complexes.     

A NOVEL OPTICALLY TRANSPARENT THIN LAYER ELECTRODE FOR IN SITU IR SPECTROELECTROCHEMISTRY

A novel design of IR OTTLE is shown to have sufficient sensitivity and experi-mental simplicity for obtaining IR spectra of the species generated during electrochemicaloxidation-reduction.     

CRYSTAL STRUCTURE OF (Et_4N)_3[Mo_2Fe_6S_8(SPH)_9]

<正> Introduction. A series Of Mo-Fe-S complexes with doublecubane structure has been synthesized and identified. Because of the similarity of its extended X-ray absorption fine structure (EXAFS) to that of FeMo cofactor and nitrogenase, suggestion has been made that the doublecubane complexes may serve as models for the Mo site of nitrogenase. Therefore, the investigation of this type of complexes has attracted much attention. By using the similar method of spontaeous self-assembly reaction, and starting from certain kinds of Mo-Fe-S compounds, we have been able to obtain several kinds of compounds, one of which     

Existence of aromatic sp~2 C-H…O = C intramolecular interaction similar to hydrogen bond

A 'H NMR signal shifted drastically to down field (δ - 10.0) at the bay area and in dose proximity to C = O group for H-1 was observed through complete assignments of 1H NMR spectra for pyridino- and benzobenzanthrones. It is concluded that this phenomenon is due not only to the anisotropy effect of C=O plus aromatic ring current effect, but also to the electrostatic attraction of C-H (δ+)…O(δ-)=C interaction. The evidence for the sp2C-H…O = C intramolecular interaction similar to hydrogen bond has also been given by EI-MS and MS/MS (CID) spectroscopy and IR spectroscopy, as well as MNDO-PM3 calculations. This new kind of interaction might be called 'quasi-hydrogen bond'.     

A Novel Mo—Doped Compound with Graphite—Like Structure：[H3O]2V3O8

1 INTRUDUCTION During the last few years, there has been much effort paid to the synthesis of new transition-metal oxides that might be active hosts for intercalation reactions. Vanadium and molybdenum in higher oxidation states with higher reacting ability tend to form polynuclear, anionic metal-oxygen clusters with an extraordinary variety of the relevant topology and electronic structures[1~3]. The preparation of the corresponding clusters is of special interest for different aspects …     

Syntheses, Crystal Structures and Characterization of Two Zeotype Crystals of K4[Cr3O(H2O)3(OOCH)6]2[P2W18O62] ·9.5H2O and K4[Cr3O(H2O)3(OOCH)6[H3P2W17Co(H2O)O61]·20H2O

Two novel zeotype crystals, K4[Cr3O(H2O)3(OOCH)6]2[P2W18O62]·9.5H2O(1) and K4 [Cr3O(H2O)3·X-ray single crystal diffraction. Crystal data: C12H43O103.5K4Cr6P2W18(1), hexagonal P6(3)/m, a=1.5895(2)nm, b=1.5895(2) nm, c=2.1620(4) nm, α=90°, β=90°, γ =120°, V=4.7305(13) nm3, Z=2,R1 =0. 0726, wR2=0. 1542; C6H57O98K4Cr3CoP2W17(2), hexagonal P6(3)/mmc, a=1. 61328 (3) nm, b=1.61328(3) nm, c=2. 06613 (9) nm, α=90°,β=90°, γ=120°, V=4. 6570(2) nm3, Z=2, R1=0. 0377,wR2 =0.1070. These crystals were characterized using elemental analysis, IR, TG-DTA, and XRD. It was found that the polyoxometalate anions maintained Wells-Dawson structure for crystal 1 and lacunary Wells-Dawson structure for crystal 2. Thermal analysis showed that crystal 1 lost the water of crystallization at 132 ℃, whereas crystal 2 lost the water of crystallization at 100 ℃. Crystal 1 could reversibly desorb and adsorb water molecules and its crystal structure could be restored after re-adsorbing the water molecules. It was also found from the XRD patterns that the void size of crystal 2 is smaller compared with that of crystal 1, which is attributed to the higher anion charges.     

CRYSTAL STRUCTURE OF TRINUCLEAR MOLYBDENUM CLUSTER H(Mo_3O(OAc)_3Cl_6)·3H_2O

<正> INTRODUCTION. Reacting of MoCl_3·3H_2O with organic ligands to-synthesize di- and trinuclear molybdenum complexes is an interesting research area. We wish to report the crystal structure of the title compound. It is one of our research results on structural chemistry of di- and trinuclear molybdenum complexes. The title compound was synthesized by reacting of MoCl_3·3H_2O with CH_3COCl。     

An MP2 study on pre-reactive complexes (CH_2)_2O … XY (X,Y = H,F,Cl,Br,I)

The structures, energies, atomic chaiges and IR spectra of complexes (CH2)2O…XY (X, Y = H, F, Cl, Br, and I) have been examined by means of ab initio molecular orbital theory at the second-order level of Moller-Plesset perturbation correction. It is found that the hydrogen bond O…H-X is non-linear. The attraction between X and the H atoms in oxirane ring causes O…H-X bond bending. The hydrogen bond slighdy weakens the bond strength of C-O, and leads the bending and stretching mode of IR to shift to the red. The calculation results show that there is no evidence of a significant extent of proton transfer to give (CH2)2OH …X- in the isolated complexes.     

STUDY ON THE CHAIN-EXTENDING REACTION OF POLY (ETHYLENE TEREPHTHALATE) WITH 2, 2′-BIS (4H-3, 1-BENZOXAZIN-4-ONE)

2,2'-Bis (4H-3, 1-benzoxazin-4-one) (BBON) has been proved to be an effective chainextender for poly (ethylene terephthalate) (PET). In order to study the reaction mechanismand kinetics of chain-extending reaction, β-bishydroxyethylene terephthalate (BHET) wasselected as model compound. The NMR data, IR spectra and number average molecularweight (M_n) of the products obtained from the reaction of BBON and BHET verify thatBBON is a hydroxyl-reactive extender. The mechanism was discussed. Kinetics dataindicate that extending reaction is a second order reaction, and BBON has high reactivity.The activation energy (E_a) was measured.     

Preparation,Characterization and Thermal Decomposition Kinetics of the Complexes [Dy(p-NBA)_3Phen]_2·3H_2O and [Dy(m-NBA)_3Phen]_2·4H_2O

The title complexes [Dy(p-NBA)3Phen]2·3H2O(I) and [Dy(m-NBA)3Phen]2·4H2O(Ⅱ) were synthesized, in the two molecular formulas of which NBA is nitrobenzoate and Phen is 1,10-phenanthroline. The characterizations of the complexes were carried out by means of elemental analysis, UV, IR, XRD and molar conductivity. The thermal decomposition of the two complexes were studied under the non-isothermal condition by DSC, TG-DTG and IR methods in detail. The kinetic parameters of the dehydration process were also obtai...     

Synthesis and Structural Characterization of [Mn（phen）2（H2O）2]（OAc）2.6H2O

1 INTRODUCTION Water oxidation to oxygen gas by photo- synthetic apparatus of green plants and cyano- bacteria is the origin of this gas in the atmosphere. The water oxidation center is a tetranuclear, oxide- bridged manganese cluster with O,N-based peri- pheral ligation by amino acid side-chain group[1, 2]. The binding of aqua to the Mn site may be impor- tant to the oxidation of aqua for producing dioxygen. 1,10-Phenanthroline has been adopted to simulate coordination sphere of manga…     

Hydrothermal Synthesis and Structure of a Novel Coordination Polymer Co_3(tma)(pda)_2(H_2O)_3]n·nH_2O

1INTRODUCTION Recently,the design and preparation of coordina-tion polymers with new porous frameworks are of great interest due to their potential functionalities such as catalysis,gas absorption,separation and molecu-lar recognition.In designing1-D,2-D and3-D porous coordination polymers,the selection of appropriate ligands is crucial for determining the structure.The mixed-linker systems of both carboxylates and pyri-dyls have proved to be effective for the preparation of novel coordi…     

CRYSTAL AND MOLECULAR STRUCTURE OF {Fe_6Mo_2S_8(S-t-Bu)_6(OMe)_3}(Et_4N)_3

<正> Introduction. The title compound has been synthesized by reaction of {(SR)_2FeMoS_4}2-with {Fe_4(SR) 10}~2- (R=t-Bu) in methanol. It is interesting to note that the complex, which involves two {Fe_3MoS_4}cubane-like clusters, is generally regarded as the best model compound for molybdenum center of nitrogenase. The synthesis and property of {Fe_6Mo_2S_8(S-tBu)_6(OMe)_3}~3- have been discribed. Although it has previously been noted that the structure of this complex is similar to its tungsten analog, the detail structural report of the title compound has not yet been given.     

XPS STUDIES ON SURFACE MODIFIED POLY [1-(TRIMETHYLSILYL)-1-PROPYNE] MEMBRANES Ⅱ SURFACE MODIFICATION BY BROMINE VAPOR*

Surface modification of poly [1-(trimethylsilyl)-1-propyne] (PTMSP) membranes bybromine vapor has been studied. It is shown that Br/C atomic ratio at the surfaces increased withthe time of bromination until about 60 min, then it reached a plateau. The results of XPS and IRstudies indicated that the addition of bromine to double bonds and the replacement of H on CH_3 bybromine had taken place so that a new peak at 286.0 eV (C--Br)in C_(1s) spectra and some newbands, e. g. at 1220 and 580cm~(-1) in IR spectra were formed. The fact,t Po_2, permeability ofoxygen, decreased and α_(O_2/N_2), separation factor of oxygen relative to nitrogen, increased withbromination time, shows that surface modification of PTMSP by bromine may be an efficient approach to prepare PTMSP membranes used for practical gas separations.     

Hydrothermal Assembly and Structural Characterization of an Octamolybdate Supported Copper (Ⅰ) Tetramer: [Cu_2(1,10-phen)_2(4,4′-bpy)]_2[Mo_8O_(26)]·4H_2O

1 INTRODUCTION The recent expansion of the field of heteropolyoxometalate chemistry derives from their vast topological structures and applicable physical properties[1～5]. One of the crucial strategies for the molecular design of solid materials is how to apply hydrothermal synthesis method to introduce some interesting transition metal coordinated fragments into the covalent backbones of solid materials. Studies have been focused on organic-inorganic hybrid materials containing one kin…