Synthesis and properties of alkyldicyclopentadienyl-vanadium(III) compounds

The compounds Cp₂VR (R = CH₃, C₂H₅, n-C₃H₇, n-C₄H₉, n-C₅H₁₁, CH₂C(CH₃)₃ or CH₂Si(CH₃)₃) have been prepared from Cp₂ VCl and RMgX in n-pentane. The air-sensitive compounds are stable at room temperature, but decompose between 65 and 138°C. The thermal stability decreases in the order R = CH₃ CH₂Si(CH₃)₃ > C₂H₅ > CH₂C(CH₃)₃ > n-C₅H₁₁ > n-C₄H₉ > n-C₃H₇. Compounds with R = i-C₃H₇ or t-C₄H₉ could not be obtained.     

Structural Characterizations of Spherical Octadecavanadates Encapsulating Na+, K+ or I- and Ellipsoidal Octadecamolybdate Encapsulating two Anions of SO42-

Polyoxoanions of tungsten, molybdenum, and vanadium have been the subject of interest since their wide variety of compositions, structures, and properties give rise to numerous important applications^[1]. From the NH₄VO₃/Na₂S_x (or (NH₄)₂S_x) reaction system we synthesized several spherical octadecavanadates with Na⁺,K⁺, NH₄⁺ or I encapsulated using hydrothermal method. These complexes include (NH₄)₁₁[V₁₈O₄₂(Na)]·(H₂O)₂₀ 1; (NH₄)₁₁[V₁₈O₄₂(K)]·(H₂O)₆, 2; (NH₄)₁₀(Na)[V₁₈O₄₂(Na)]·(H₂O)₂₆, 3; (NH₄)₁₁[V₁₈O₄₂(NH4]·(H₂O)₂₀, 4; and (NH₄)₂₀(I)₇[V₁₈O₄₂(I)]·(H₂O)₁₂, 5, in which the structures of 1, 2, 3, and 5 have been determined by X-ray analyses. In the analogous reaction system of (NH₄)₂MoS₄/(NH₄)₂S_x, we also obtained one ellipsoidal octadecamolybdate, (NH₄)₄[Mo₁₈O₅₄(2SO₄)]·(H₂O)₄, 6 with a standard Wells-Dawson structure^[2]. The Ortep drawings of the two kinds of structures are viewed as follows.     

Übergangsmetall-silyl-komplexe L. darstellung, struktur und reaktivität der Trihydrido-Silyl-und -Stannyl-Komplexe L3FeH3(ER3) (E =Si,

Photochemical reaction of (CO)₂(dppe)Fe(H)(SiR₃) with HSiR₃ (SiR₃ = Si(OMe)₃, Si(OEt)₃, SiMe₃, SiMe₂Ph, SiPh₃) yields the trihydrido silyl complexes (CO)(dppe)FeH₃(SiR₃ ). The analogous complexes (PR′Ph₂)₃ FeH₃(ER₃) are prepared by reaction of the H₂ -complexes (PR′Ph₂)₃FeH₂(H₂) with HER₃ (ER₃ = SiMe₃, SiMC₂Ph, SiMePh₂, SiPh₃, Si(Me₂)OSi(Me₂)H, SnPh₃, SnEt₃). Additional derivates of (CO) (dppe)FeH₃(SiR₃) (SiR₃ = SiMePh₂) and (PR′Ph₂)₃FeH₃(SiR₃) (SiR₃ = Si(OMe)₃, SiH₂Ph, SiHPh₂, Si(OEt)₃, SiMePhCl) are accessible by silane exchange starting from (CO)(dppe)FeH₃(SiMe₃) and (PR′Ph₂) ₃FeH₃(SiMe₃). (PBuPh₂)₃FeH₃(SiMePh₂) was also prepared from (PBuPh₂)₃FeH₂(N₂) and HSiMePh₂, and (PBuPh₂)₃FeH₃(SnMe₃) from (PBuPh₂)₃FeH₂(H₂) and Me₃SnCl. The complex (PBuPh₂) ₃FeH₃(SnMe₃) crystallizes as a toluene solvate in the cubic space group I 3d and shows crystallographically imposed C₃-symmetry. The complexes (CO)₂ (dppe)Fe(H)(SiR₃) and (PR′Ph₂)₃FeH₃(ER₃) are highly dynamic in solution. Low temperature NMR measurements and the E, Fe, H coupling constants strongly indicate that the exchange mechanism involves η²-HER₃ ligands.     

Template reactions with polynuclear complexes. The reaction of [Mo2(O2CCF3)4(PR3)2] (R = Ph, Et) with 2-aminobenzaldehyde

The binuclear molybdenum(II) complexes [Mo₂(O₂CCF₃)₄(PR₃)₂] (R = Ph, Et) act as templates for the self-condensation of 2-aminobenzaldehyde to give a new class of complexes in which a hydride ion bridges two molybdenum(III) centres, each of which carries a tetradentate macrocyclic ligand (C). The new hydrido complexes [Mo₂(C)₂ (H)(O₂CCF₃)₃(PPh₃)₂] (I), [Mo₂(C)₂(H)₂(O₂CCF₃)₂(PPh₃)₂] (II), and [Mo₂(C)₂ (H)₂(O₂CCF₃)₂(PEt₃)₂]₂ (V) exist in two or more isomeric forms as shown by their IR, ¹H, ³¹P and ¹⁹F NMR spectra. Substitution with thiocyanate, nitrate and tetraphenylborate anions gives the new products [Mo₂(C)₂(H)(CO)(NCS)₃(PPh₃)₂] (III), [Mo₂(C)₂ (H)₂(O₂CCF₃)(NO₃)(PPh₃)₂] (IV), [Mo₂(C)₂(H)(O₂CCF₃)(PPh₃)₂](BPh₄)₂ (VI) and [Mo₂(C)₂(H)₂(O₂CCF₃)(PEt₃)₂](BPh₄) (VII), which also exist in isomeric forms.     

异质结型光催化膜的活性及其机理研究

采用浸渍提拉法制得TiO₂,ZnO,Fe₂O₃,ZnO/TiO₂,TiO₂/ZnO,Fe₂O₃/TiO₂和TiO₂/Fe₂O₃石英玻璃基底负载膜.光催化降解亚甲基蓝实验表明,TiO₂和ZnO具有良好的光催化活性,Fe₂O₃活性较差.但形成异质结后,TiO₂和Fe₂O₃的光催化降解能力发生明显的变化.用254nm紫外光光照后,TiO₂,ZnO和Fe₂O₃等3种氧化物膜与水的接触角均有不同程度的降低,TiO₂表现出超亲水性,ZnO/TiO₂和Fe₂O₃/TiO₂膜与水的接触角小于对应的单纯ZnO和Fe₂O₃膜与水的接触角,其中Fe₂O₃/TiO₂表面出现超亲水性.瞬态光电导谱的少数载流子寿命的测定表明,异质结势垒电场能有效地增强光生电子-空穴对的分离效率.根据能带理论建立的两组异质结能带模型可合理地解释实验结果.     

恒温石墨炉中基体对钾和镉的影响

电热原子化原子吸收分析易受基体的干扰,使得准确度的提高受到限制.有关减少和消除这个影响已有报导^[1-6]。Czobik等^[6]人曾指出,为减少和消除基体的干扰,应设计一种具有时间和空间上等热条件的石墨炉。恒温石墨炉有上述的性质,用它作原子化器能消除和减少基体的影响。     

双核钼(Ⅴ)二乙基二硫代氨基甲酸络合物的歧化离解平衡及其离解常数

由于发生歧化离解,Mo₂O₃(S₂CNEt₂)₄的溶液不遵守Beer定律,我们测定了有关溶液的光吸收性质以及Mo₂O₃(S₂CNEt₂)₄的歧化离解常数,于15℃时数值为2.2×10^-4。     

Ruthenium(II) complexes with mono and ditertiary arsines and phosphines and their reaction with small molecules

Dichlorotetrakis(dimethylsulphoxide)ruthenium(II) reacts with AsPh₃ AsMePh₂, AsMe₂Ph and SbPh₃ in ethanolic hydrochloric acid solution to yield the complexes RuCl₂(DMSO)₂(AsPh₃)₂, RuCl₂(DMSO) L₂ (L = AsMePh₂, AsMe₂Ph, SbPh₃) respectively. The treatment of ruthenium(II) blue solution with AsMePh₂, AsMe₂Ph and SbPh₃ in alcohol resulted in the formation of the complexes; RuCl₂L₃ (L = AsMePh₂, AsMe₂Ph and SbPh₂), respectively. The reaction of RuCl₂(DMSO)₄ with the bidentate ligands 1,2 bis (diphenylarsino)methane (DPAM), 1,2 bis(diphenylarsino)ethane (DPAE) and 1,2 bis (diphenylphosphino)methane (DPPM). 1,2 bis(diphenylphosphino)ethane (DPPE), in ethanol gave the complexes RuCl₂(DPAM)₂, RuCl₂(DPAE)₂, RuCl₂ (DPPM)₂ RuCl₂(DPPE)₂, respectively. The complexes thus obtained undergo reaction with carbon monoxide, hydrogen, molecular nitrogen and nitric oxide to yield a variety of mixed ligand complexes.     

The formation and stability of hydrated and anhydrous uranyl phosphates

The stabilities of the hydrated uranyl phosphates (UO₂)₃(PO₄)₂ · 4 H₂O, UO₂HPO₄ · 4 H₂O, and UO₂(H₂PO₄) · 3 H₂O have been reinvestigated. The compounds identified by thermal analysis have been prepared isothermally and characterized by their strongest X-ray reflections. During dehydration, oxygen was not evolved and the crystalline compounds (UO₂)₃(PO₄)₂, (UO₂)₂P₂O₇, UO₂(PO₃)₂, and probably (UO₂)₃P₄O)₁₃ were found.

At still higher temperatures, the uranyl phosphates are reduced. The decomposition products lose phosphorus oxide above 1300–1400°C. The present results are summarized in a tentative pseudo-binary phase diagram UO_x(x = 3 to 2)—UO₂(PO₃)₂.     

Profiles of ethylene polymerization with zirconocene–trialkylaluminum/borane compound

Ethylene polymerization was conducted with bis(cyclopentadienyl)zirconium dichloride (1) and rac-dimethylsilylenebis(indenyl)zirconium dichloride (2) combined with trialkylaluminum (AlR₃; R=methyl (Me), ethyl (Et), isobutyl (iBu))/triphenylcarbenium tetrakis(pentafluorophenyl)borate (Ph₃CB(C₆F₅)₄) or tris(pentafluorophenyl)borane (B(C₆F₅)₃) to study the effect of cocatalysts on polymerization rate (R_p). When AlMe₃ was used, no activity or very low activity was observed with both zirconocenes regardless of the borane compounds used. The replacement of AlMe₃ to AlEt₃ or AliBu₃ with 1–AlR₃/Ph₃CB(C₆F₅)₄ caused polymerization and induction time was observed to reach the maximum R_p. Especially in the case of using AlEt₃, it took about 30 min to show the activity. When B(C₆F₅)₃ was used, AlEt₃ was not effective but AliBu₃ gave the highest activity among all the combinations of AlR₃ and the borane compounds. In the case of polymerization with 2 using Ph₃CB(C₆F₅)₄, high activity was observed with both AlEt₃ and AliBu₃ without any induction period. When B(C₆F₅)₃ was used instead of Ph₃CB(C₆F₅)₄, very low activity was observed with AlEt₃. On the other hand, high activity was observed with AliBu₃, and the maximum R_p was found at the beginning of the polymerization. The effect of AlR₃ on the formation of active species was discussed based on these results.     

Ab initio study of the electronic spectrum of dichlorocarbene CCl2

The equilibrium geometries, excitation energies, force constants and vibrational frequencies for seven low-lying electronic states X ¹A₁, ¹B₁, ³B₁, ¹A₂, ³A₂, ¹B₂ and ³B₂ of dichlorocarbene CCl₂ have been calculated at the MRSDCI level with a double-zeta plus polarization basis set. Our calculated equilibrium geometry for the X ¹A₁ state, excitation energy for X ¹A₁ → ¹B₁ and vibrational frequencies for the X ¹A₁ and ¹B₁ states are in good agreement with experimental data. The electronic transition dipole moments, oscillator strengths for the ¹B₁ → X ¹A₁ and ¹B₂ → X ¹A₁ transitions, radiative lifetimes for the ¹B₁ and ¹B₁ states are calculated using MRSDCI wavefunctions, predicting results in reasonable agreement with experiment.     

Arylkomplexe des typs trans-[Ir(Ar)(CO)(PPh3)2]

The preparation and properties as well as some reactions of a series of arylcarbonylbis(triphenylphosphine)iridium(I) complexes [Ir(Ar)(CO)(PPh₃)₂] (Ar = C₆H₅, C₆F₅, 2-C₆H₄CH₃, 3-C₆H₄CH₃, 4-C₆H₄CH₃, 2-C₆H₄OCH₃, 2,6-C₆H₃-(OCH₃)₂, 4-C₆H₄N(CH₃)₂, 3-C₆H₄Cl, 4-C₆H₄Cl, 4-C₆H₄Cl, 3-C₆H₄CF₃, 4-C₆H₄CF₃) are described, and the most important IR data as well as the ³¹P NMR parameters of these, without exception trans-planar, compounds are given.

Some of the complexes react with molecular oxygen to form well defined dioxygen adducts [Ir(Ar)(O₂)(CO)(PPh₃)₂] (Ar = C₆H₅, 3-C₆H₄CH₃, 4-C₆H₄CH₃). Complexes with ortho-substituted aryl ligands are not oxygenated. This effect is referred to as a steric shielding of the metal center by the corresponding ortho-substituents. With SO₂ the similar irreversible addition compound [Ir(4-C₆H₄CH₃)-(SO₂)(CO)(PPh₃)₂] is obtained. Sulfur dioxide insertion into the Ir---C bond cannot be observed.

The first step of the reaction between [Ir(4-C₆H₄CH₃)(CO)(PPh₃)₂] and hydrogen chloride involves an oxidative addition of HCl to give [Ir(H)(Cl)(4-C₆-H₄CH₃)(CO)(PPh₃)₂]. Ir---C bond cleavage by reductive elimination of toluene from the primary adduct does not occur except at elevated temperature.     

Perfluoromethyl—element-liganden : XX. Bildung von heteronuclearen zweikernkomplexen des typs mm′(CO)nXY (M = Mn; M′ = Re, Co)

The reactions of MnRe(CO)₁₀ with As₂(CF₃)₄ and MnCo(CO)₉ with P₂(CF₃)₄, As₂(CF₃)₄, S₂(CF₃)₂, Se₂(CF₃)₂, (CF₃)₂EI (E = P, As), (CF₃)₂AsH, (CF₃)₂AsE′CF₃ (E′ = S, Se), (CF₃)₂PSeCF₃, Me₂AsI and (CF₃)₂PPMe₂, respectively, have been studied under various conditions. Besides already known mono- and binuclear compounds the heteronuclear complexes MnRe(CO)₈[As(CF₃)₂]₂ and MnCo(CO)₇[E(CF₃)₂]₂ (E = P, As) are formed. The reactions proceed via cleavage of the M---M′ bond and formation of the mononuclear species Mn(CO)₅X and M′(CO)_nY (M′ = Re, n = 5; M′ = Co, n = 4).     

Preparation and X-ray crystal structures of mixed ligand complexes containing the S3N ligand

Reaction of Hg(S₇N)₂ with cis- PtCl₂(PR₃)₂ (PR₃ = PPh₃, PPh₂Me, PPHMe₂, PEt₃) in the presence of Na[PF₆] gives [Pt(S₃N)(PR₃)₂][PF₆] in 32–46% yield. The complexes have been characterized by IR, NMR and microanalyses. The X-ray crystal structures of two examples (PR₃ = PPh₂Me and PEt₃) show that the S₃N⁻ ligand coordinates in a bidentate fashion via two sulphur atoms.     

Synthesis and properties of some diruthenium acetate compounds

The compound [Ru₂(μ-O₂CCH₃)₄(THF)₂]BF₄ (I) containing the Ru₂⁵⁺ unit was prepared by reaction of Ru₂Cl(μ-O₂CCH₃)₄ with AgBF₄ in THF. This compound, in contrast with Ru₂Cl(μ-O₂CCH₃)₄, is soluble in several polar organic solvents and reacts in THF with OPPh₃ and PPh₃ giving [Ru₂(μ-O₂CCH₃)₄(OPPh₃)₂]BF₄·CH₂Cl₂ (II) and [Ru(μ-O₂CCH₃)(O₂CCH₃)(PPh₃)]_n (III), respectively. The complex II has been also obtained as hexafluorophosphate [Ru₂(μ-O₂CCH₃)₄(OPPh₃₂]PF₆·CH₂Cl₂ (IV) by treatment of Ru₂Cl(μ-O₂CCH₃)₄ with an excess of NOPF₆ and PPh₃ in methanol. In this reaction the triphenylphosphine oxide is generated by oxidation of the triphenylphosphine.     

Complex formations of silver(I) trifluoroacetate and trifluoromethanesulfonate with benzene and cyclohexene

An apparatus for measurements of equilibrium ligand vapor pressure has been applied in order to determine the stoichiometry of benzene and cyclohexene complexes of silver(I) trifluoroacetate (AgCF₃CO₂) and silver(I) trifluoromethanesulfonate (silver(I) triflate, AgCF₃SO₃) in the solid state. It has been found that the equilibrium leads the formation of such complexes as: (AgCF₃CO₂)₂(C₆H₆), (AgCF₃CO₂)₂(C₆H₁₀), (AgCF₃CO₂)₂(C₆H₁₀)₃, (AgCF₃SO₃)₂(C₆H₆), (AgCF₃SO₃)(C₆H₆), (AgCF₃SO₃)(C₆H₁₀) and (AgCF₃SO₃)(C₆H₁₀)₂. The temperature dependence of the gas-solid equilibrium ligand pressure has also been examined for these complexes, and the enthalpy and entropy changes according to the following complex dissociation reactions were estimated: (AgCF₃CO₂)L_m (s) AgCF₃CO₂ (s)+mL (g): and (AgCF₃SO₃)L_n (s) AgCF₃SO₃ (s)+nL (g), where L's are benzene and cyclohexene. On the basis of the thermodynamic data obtained, the effects of the counter anion as well as the ligand on the complex stability are discussed.     

Electron paramagnetic resonance study of the reactions of tetrathiomolybdate with roussin salts and esters, and with some related iron nitrosyls

The tetrathiomolybdate ion [MoS₄]²⁻ reacts in DMF solution with Roussin esters Fe₂(SR)₂(NO)₄ (R = Me, Et, n-Pr, i-Pr, n-Bu,t-Bu, n-C₅H₁₁) to yield the paramagnetic iron nitrosyls [Fe(NO)₂(SR)₂]⁻ (1), [Fe(NO)₂(S₂MoS₂]⁻ (2) and [Fe(NO)(S₂MOS₂)₂]⁻ (3). The new complexes (2) and (3) have been characterized by EPR spectroscopy and the assignment to them of constitutions based respectively upon tetrahedral and square pyramidal iron is supported by EHMO calculations. Fe₂(SPh)₂(NO)₄ with [MoS₄]²⁻ yields only [Fe(NO)₂(SPh)₂]⁻, and preformed (3) reacts with PhS⁻ to give firstly EPR-silent species, and then [Fe(NO)₂(SPh)₂]⁻. The mononitrosyl (3) can also be formed by reaction of [MoS₄]²⁻ with [Fe₄S₃(NO)₇]⁻, Fe₄S₄(NO)₄, or Fe₂I₂(NO)₄.     

Reactions of tetrakis(trifluoromethyl) diphosphine and bis(trifluoromethyl) phosphine with ruthenium carbonyl clusters; X-ray structure of tetraruthenium carbonyl cluster derivatives

Reaction of [Ru₃(CO)₁₂ with (CF₃)₂P---P(CF₃)₂ in p-xylene at 140°C yielded the compounds [Ru₄(CO)₁₃{μ-P(CF₃)₂}₂] (1), [Ru₄(CO)₁₄{μ-P(CF₃)₂}₂] (2) and [Ru₄(CO)₁₁{μ-P(CF₃)₂}₄] (3). Reaction with [(μ-H)₄Ru₄(CO)₁₂] under similar conditions yielded [(μ-H)₃Ru₄(CO)₁₂{μ-P(CF₃)₂}] (4). All four compounds have been characterised by X-ray crystallography. The fluxional behaviour of the hydrides in 4 has also been studied by variable-temperature NMR spectroscopy. Compounds 1, 2 and 4 were also obtained from the reactions of Ru₃(CO)₁₂ with (CF₃)₂PH in dichloromethane at 80°C.     

Conversion of rhenium alkylidyne complexes that contain unsupported metal-metal double bonds into relatives that contain μ-alkylidyne ligands

Photolysis of compounds of the type [Re(CCMe₂R)(OR′)₂] (R = Me or Ph; OR′ = O′Bu, OCMe₂(CF₃), or OCMe(CF₃)₂) in benzene with a medium pressure mercury lamp yields compounds of the type [Re(OR′)₂]₂(μ-CCMe₂R)₂ in an intramolecular and irreversible manner. [Re(CCMe₂R)(OR′)₂]₂ and [Re(OR′)₂]₂(μ-CCMe₂R)₂ (OR′ = O′Bu or OCMe₂(CF₃)₂) both react with excess carbon monoxide in several solvents to afford the dimers [Re(OR′)₂(CO)]₂(μ-CCMe₂R)₂ quantitatively. An X-ray study of [Re(O^tBu)₂(CO)]₂ (μ-C^tBu)₂ shows it to consist of two distorted trigonal bipyramids connected by two symmetrically bridging neopentylidyne ligands. The unbridged dimers of general formula [Re(CCMe₂R)(OR′)₂]₂ do not react readily with simple substrates such as phosphines, olefins, or acetylenes, although [Re(CCMe₂R)(O^tBu)₂]₂ can be oxidized by iodine to yield Re(CCMe₂R)(O^tBu)₂I₂ in good yield. In contrast, {Re[OCMe(CF₃)₂]₂}₂(μ-C^tBu)₂ reacts with one equivalent of phenylacetylene to give a species in which one of the two bridging alkylidyne ligands is retained.     

SnO_2/TiO_2纳米管复合光催化剂的性能及失活再生

基于微波水热法和微乳液法合成SnO2/TiO2纳米管复合光催化剂.通过X射线衍射(XRD)、配有能量色散X射线光谱仪(EDX)的透射电镜(TEM)和电化学手段对光催化剂进行表征.以甲苯为模型污染物,考察光催化剂在紫外光(UV)和真空远紫外光(VUV)下的性能及失活再生.结果表明,SnO2/TiO2纳米管复合光催化剂形成三元异质结(锐钛矿相TiO2(A-TiO2)/金红石相TiO2(R-TiO2)、A-TiO2/SnO2和R-TiO2/SnO2异质结),促使光生电子-空穴对的有效分离,提高光催化活性.SnO2/TiO2表现出最佳的光催化性能,UV和VUV条件下的甲苯降解率均达100%,CO2生成速率(k2)均为P25的3倍左右.但由于UV光照矿化能力不足,中间产物易在催化剂表面累积.随着UV光照时间的增加,SnO2/TiO2逐渐失活,20 h后k2由138.5 mg·m-3·h-1下降到76.1 mg·m-3·h-1.利用VUV再生失活的SnO2/TiO2,过程中产生的·OH、O2-·、O(1D)、O(3P)、O3等活性物质可氧化吸附于催化剂活性位的难降解中间产物,使催化剂得以再生,12 h后k2恢复到143.6 mg·m-3·h-1.UV和VUV的协同效应使UV降解耦合VUV再生成为一种可持续的光催化降解污染物模式.