Controlled Ethylene Polymerization Catalyzed by Cp$\rm{{_{2}^{\ast}}}$ZrBu2/[Ph3C] [B(C6F5)4]/iBu4Al2O above Room Temperature

The ternary system composed of Cp ZrBu₂ (Cp*=Me₅Cp), [CPh₃][B(C₆F₅)₄], and tetraisobutyldialuminoxane (TIBAO) catalyzed the polymerization of ethylene in a controlled fashion at temperatures up to 60 °C. The consumption of ethylene remained constant during the polymerization process, the molecular weight of the polyethylene increased linearly with time, and polydispersity indexes down to 1.3 were obtained. Characterization of the polyethylene by ¹³C‐NMR and FT‐IR spectroscopy did not indicate any branching or CC linkages, even for polymer produced at 40 °C or above. The linear and saturated polymer structure is due to the absence of β‐hydride transfer, β‐hydride elimination and chain walking during the polymerization. The absence of termination reactions is consistent with the system's demonstrated controlled polymerization.     

Syntheses and Crystal Structures of Ammoniates with the Phenyl‐Substituted Polytin Anions Sn2Ph$\rm{_{\bf 4}^{{\bf 2} - } }$, cyclo‐Sn4Ph$\rm{_{\bf 4}^{{\bf 4} - } }$, and Sn6Ph$\rm{_{{\bf 12}}^{{\bf 2} - } }$

The reaction of diphenyltin dichloride with the binary Zintl phase K₄Sn₉ in the presence of excess lithium and 18‐crown‐6 in liquid ammonia led to the ammoniate [K(18‐crown‐6)(NH₃)₂]₂Sn₂Ph₄ ( 1 ). The analogous reaction with K₄Ge₉ and potassium in the absence of further alkali metal ligands resulted in the compound [K₂(NH₃)₁₂]Sn₆Ph₁₂ ? 4 NH₃ ( 3 ). Cs₆[Sn₄Ph₄](NH₂)₂ ? 8 NH₃ ( 2 ) was prepared by reacting diphenyltin dichloride with a surplus of caesium in liquid ammonia. The low‐temperature single‐crystal structure determinations show all compounds to contain phenyl‐substituted polyanions of tin. Compound 1 is built from Sn₂Ph anions consisting of Sn dumbbells with two Ph substituents at each Sn‐atom. Compound 2 contains cyclo‐Sn₄Ph anions formed by a four‐membered tin ring in butterfly conformation with one Ph substituent at each Sn‐atom in an (all‐trans)‐configuration. Sn₆Ph in 3 is a zig‐zag Sn₆ chain with two substituents at each of the Sn‐atoms. Both 1 and 3 have molecular counter cations, in the latter case the unprecedented dinuclear potassiumammine complex [K₂(NH₃)₁₂]²⁺ is observed. Compound 2 shows a complicated three‐dimensional network of Cs? Sn interactions.     

On the loss of ethylene from [C3H7O]+ ions of structure \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} {\rm CH}_{\rm 2} \mathop {{\rm CHOH}}\limits^{\rm + } $\end{document}

The results of some ³C and ²H labelling experiments plus some measurements of reaction thermochemistry and translational energy releases, permit a significant simplification of the mechanistic pathways by which [C₃H₇O]⁺ ions of structure fragment by loss of C₂H₄. The relationships between these ions and some of their isomeric forms are explored and clarified.     

Unimolecular reactions of isolated organic ions: The chemistry of the unsaturated oxonium ion \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 2} = {\rm CHCH =}\mathop {{\rm OCH}_{\rm 3}}\limits^{\rm +} $\end{document}

The reactions of metastable $ {\rm CH}_{\rm 2} = {\rm CHCH =}\mathop {{\rm OCH}_{\rm 3}}\limits^{\rm +} $ oxonium ions generated by alkyl radical loss from ionized allylic alkenyl methyl ethers are reported and discussed. Three main reactions occur, corresponding to expulsion of H₂O, C₂H₄/CO and CH₂O. There is also a very minor amount of C₃H₆ elimination. The mechanisms of these processes have been probed by ²H- and ¹³C-labelling experiments. Special attention is given to the influence of isotope effects on the kinetic energy release accompanying loss of formaldehyde from ²H-labelled analogues of $ {\rm CH}_{\rm 2} = {\rm CHCH =}\mathop {{\rm OCH}_{\rm 3}}\limits^{\rm + } $. Suggestions for interpreting these reactions in terms of routes involving ion–neutral complexes are put forward.     

Voltammetric Behavior of MoS$\rm{ {_{4}^{2-}}}$ and SbS$\rm{ {_{4}^{3-}}}$ as Possible Components of “Dissolved Sulfide” in Oxic Natural Waters

Nanomolar concentrations of dissolved sulfide have been observed in O₂‐ bearing natural waters. The sulfide consists of oxidation‐resistant, unknown chemical components that might include metal‐sulfide complexes, elemental sulfur in various forms or organic sulfur compounds. Here we show that thioanions are also plausible components. Tetrathiomolybdate and tetrathioantimonate ions deposit respectively 3 and 4 equivalents of HgS at mercury electrodes. In cathodic stripping voltammetry, a common method to quantify nanomolar sulfide in nature, MoS and SbS would therefore contribute to “total dissolved sulfide.” Limited evidence suggests that thioanions may be powerful complexing agents that would be capable of affecting trace metal speciation and bioavailability in natural waters.     

Electrochemical Study of PW12O$\rm{_{40}^{3-}}$ in Poly(ethylene glycol) Electrolyte

The electrochemical properties of PW₁₂O (abbreviated as PW₁₂) anion in poly(ethylene glycol) (PEG) have been studied by cyclic voltammetry, complex impedance and FT‐IR spectroscopy. The PW₁₂ anion in PEG‐LiClO₄ electrolyte shows reasonable facile electrochemistry, and the diffusion coefficients of PW₁₂ were measured with microelectrode. It is shown that ionic conductivity of polymer electrolytes based on low molecular weight PEG can be improved by the addition of PW₁₂. The increase of conductivity is coupled with decrease of transient cross‐links density of polymer chains which is evidenced by the downshift of C? O? C stretching mode. The phenomena are explained in view of ion‐ion and ion‐polymer interactions.     

Electrochemiluminescence Sensor Based on Multiwalled Carbon Nanotubes Doped Polyvinyl Butyral Film Containing Ru(bpy)$\rm{ {_{3}^{2+}}}$ as Chemiluminescence Reagent

An effective electrochemiluminescence (ECL) sensor was developed by combining Ru(bpy) with multiwalled carbon nanotubes(MWNTs) doped polyvinyl butyral (PVB) film. The doped film can prevent the leakage of Ru(bpy) efficiently and the immobilized Ru(bpy) kept its electrocatalytic activity toward the electrooxidation of tripropylamine (TPA), suggesting PVB and MWNTs were proper matrix to immobilize Ru(bpy) by hydrophobic interaction. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and electrochemiluminescent characterization were employed to study the presented sensor. A wide linear dynamic range of 6 orders of magnitude between ECL intensity and concentration of TPA was found from 1×10^?8 M to 5×10^?2 M, with a detection limit of 3.5×10^?9 M.     

Electrochemical Study on Hydrogen Evolution and \begin{document}${\rm C}\rm{O}$\end{document}\begin{document}$_\rm{2}$\end{document} Reduction on Pt Electrode in Acid Solutions with Different pH

Hydrogen evolution reaction (HER) is the major cathodic reaction which competes \begin{document}${\rm C}\rm{O}_\rm{2}$\end{document} reduction reaction (\begin{document}${\rm C}\rm{O}_\rm{2}$\end{document} RR) on Pt electrode. Molecular level understanding on how these two reactions interact with each other and what the key factors are of \begin{document}${\rm C}\rm{O}_\rm{2}$\end{document} RR kinetics and selectivity will be of great help in optimizing electrolysers for \begin{document}${\rm C}\rm{O}_\rm{2}$\end{document} reduction. In this work, we report our results of hydrogen evolution and \begin{document}${\rm C}\rm{O}_\rm{2}$\end{document} reduction on Pt(111) and Pt film electrodes in \begin{document}${\rm C}\rm{O}_\rm{2}$\end{document} saturated acid solution by cyclic voltammetry and infrared spectroscopy. In solution with pH > 2, the major process is HER and the interfacial pH increases abruptly during HER; \begin{document}${\rm C}\rm{O}_\rm{ad}$\end{document} is the only adsorbed intermediate detected in \begin{document}${\rm C}\rm{O}_\rm{2}$\end{document} reduction by infrared spectroscopy; the rate for \begin{document}${\rm C}\rm{O}_\rm{ad}$\end{document} formation increases with the coverage of UPD-H and reaches maximum at the onset potential for HER; the decrease of \begin{document}${\rm C}\rm{O}_\rm{ad}$\end{document} formation under HER is attributed to the available limited sites and the limited residence time for the reduction intermediate (\begin{document}$\rm{H}_\rm{ad}$\end{document}), which is necessary for \begin{document}${\rm C}\rm{O}_\rm{2}$\end{document} adsorption and reduction.     

Electrochemiluminescent Determination of Chlorphenamine Maleate Based on Ru(bpy)$\rm{ {_{3}^{2+}}}$ Immobilized in a Nano‐Titania/Nafion Membrane

The immobilization of tris(2,2'‐bipyridyl)ruthenium(II) [Ru(bpy) ] in a TiO₂/Nafion nanocomposites membrane modified glassy carbon electrode (GCE) was achieved via both an ion‐exchange process and hydrophobic interactions .The surface‐confined Ru(bpy) shows good electrochemical and photochemical activities. The Ru(bpy) underwent reversible surface process and reacted with chlorphenamine maleate (CPM) to produce electrochemiluminescence. The modified electrode was used for the ECL determination of CPM. It showed good linearity in the concentration range from 2×10^?8 g/mL to 1×10^?6 g/mL (R=0.9995) with a detection 6×10^?9 g/mL (S/N=3). The relative standard derivation (n=11) was 2%. This method is developed for the determination of CPM with simplicity and high sensitivity.     

The Photochemical Behavior of the Uranyl Ion (UO$\rm{{_{2}^{2+}}}$): a Dimer Perspective and Outlook

The complex formation of uranyl (UO ) with oxalic acid (HOOC? COOH) in acetone is studied by UV/VIS, absorption, luminescence, and excitation spectroscopy. Based on solid‐state crystallographic data, we propose a dimer structure with D_2h symmetry for the complex in solution. This symmetry is vibrationally distorted to D₂ by the out‐of‐plane equatorial‐ligand vibration. From the spectroscopic point of view, this vibration induces intensity in the transitions Π_g←Σ and one component of Δ_g←Σ . From the photochemical point of view, this vibration induces a twisting mechanism that destroys the complex. From the theoretical point of view, it is worthwhile to notice that the symmetry of the odd out‐of‐plane vibration is the same as the symmetry of the odd LUMO (f_xyz). By vibrating accordingly to the LUMO symmetry, the complex is self‐destroying by absorption of light, and the uranyl is regenerated. A small comment is devoted to a possible δ–δ interaction and the quintuple U₂ bond distance proposed by Gagliardi and Ross [29].     

NH\begin{document}$ _\textbf{2} $\end{document}-MIL-53(Al) for Simultaneous Removal and Detection of Fluoride Anions

To address the limitations of the separate fluoride removal or detection in the existing materials, herein, amino-decorated metal organic frameworks NH\begin{document}$ _2 $\end{document}-MIL-53(Al) have been succinctly fabricated by a sol-hydrothermal method for simultaneous removal and determination of fluoride. As a consequence, the proposed NH\begin{document}$ _2 $\end{document}-MIL-53(Al) features high uptake capacity (202.5 mg/g) as well as fast adsorption rate, being capable of treating 5 ppm of fluoride solution to below the permitted threshold in drinking water within 15 min. Specifically, the specific binding between fluoride and NH\begin{document}$ _2 $\end{document}-MIL-53(Al) results in the release of fluorescent ligand NH\begin{document}$ _2 $\end{document}-BDC, conducive to the determination of fluoride via a concentration-dependent fluorescence enhancement effect. As expected, the resulting NH\begin{document}$ _2 $\end{document}-MIL-53(Al) sensor exhibits selective and sensitive detection (with the detection limit of 0.31 \begin{document}$ \mu $\end{document}mol/L) toward fluoride accompanied with a wide response interval (0.5-100 \begin{document}$ \mu $\end{document}mol/L). More importantly, the developed sensor can be utilized for fluoride detection in practical water systems with satisfying recoveries from 89.6% to 116.1%, confirming its feasibility in monitoring the practical fluoride-contaminated waters.      

Structural Characterization of Some Coinage Metal(I) Thiosulfate Complexes, $\rm M^{1}_{a}M\rm ^{2}_{b}(X_{c}) (S_{2}O_{3})_{d}(\cdot eS)$ (M1 = Group 1 Cation,X = Univalent Anion,M2 = CuI,AgI, S = Solvent)

Building on previous single crystal X‐ray structure determinations for the group 1 salts of complex thiosulfate/univalent coinage metal anions previously defined for (NH₄)₉AgCl₂(S₂O₃)₄, NaAgS₂O₃·H₂O and Na₄[Cu(NH₃)₄][Cu(S₂O₃)₂]·NH₃, a wide variety of similar salts, of the form , M¹ = group 1 metal cation, M² = univalent coinage metal cation (Cu, Ag), (X = univalent anion), most previously known, but some not, have been isolated and subjected to similar determinations. These have defined further members of the isotypic, tetragonal series, for M¹ = NH₄, M² = Cu, Ag, X = NO₃, Cl, Br, I, together with the K/Cu/NO₃ complex, all containing the complex anion [M²(SSO₃)₄]^7? with M² in an environment of symmetry, Cu, Ag‐S typically ca. 2.37, 2.58Å, with quasi‐tetrahedral S‐M‐S angular environments. Further salts of the form , n = 1‐3, have also been defined: For n = 3, M² = Cu, M¹/x = K/2.25 or 1 5/6, NH₄/6, (and also for the (NH₄)₄Na/4H₂O·MeOH adduct) the arrays take the form with distorted trigonal planar CuS₃ coordination environments, Cu‐S distances being typically 2.21Å, S‐Cu‐S ranging between 105.31(4)–129.77(4)°; the silver counterparts take the form for M¹ = K, NH₄. For n = 2, adducts have only been defined for M² = Ag, the anions of the M¹ = Na, K adducts being dimeric and polymeric respectively: Na₆[(O₃SS)₂Ag(μ‐SSO₃)₂Ag(SSO₃)]·3H₂O, K₃[Ag(μ‐SSO₃)₂]_(∞|∞)·H₂O; a polymeric copper(I) counterpart of the latter is found in Na₅Cu(NO₃)₂(S₂O₃)₂ ≡ 2NaNO₃·Na₃[Cu(μ‐SSO₃)₂]_(∞|∞). For n = 1, NaAgS₂O₃, the an‐ and mono‐ hydrates, exhibit a two‐dimensional polymeric complex anion in both forms but with different contributing motifs. (NH₄)₁₃Ag₃(S₂O₃)₈·2H₂O takes the form (NH₄)₁₃[{(O₃SS)₃Ag(μ‐SSO₃)}₂Ag], a linearly coordinated central silver atom linking a pair of peripheral [Ag(SSO₃)₄]^7? entities. In Na₆[(O₃SS)Ag(μ‐SSO₃)₂Ag(SSO₃)]·3H₂O, the binuclear anions present as Ag₂S₄ sheets, the associated oxygen atoms being disposed to one side, thus sandwiching layers of sodium ions; the remarkable complex Na₅[Ag₃(S₂O₃)₄]_(∞|∞)·H₂O is a variant, in which one sodium atom is transformed into silver, linking the binuclear species into a one‐dimensional polymer. In (NH₄)₈[Cu₂(S₂O₃)₅]·2H₂O a binuclear anion of the form [(O₃SS)₂Cu(μ‐S.SO₃)Cu(SSO₃)₂]^8? is found; the complex (NH₄)₁₁Cu(S₂O₃)₆ is 2(NH₄)₂(S₂O₃)·(NH₄)₇[Cu(SSO₃)₄]. A novel new hydrate of sodium thiosulfate is described, 4Na₄S₂O₃·5H₂O, largely describable as sheets of the salt, shrouded in water molecules to either side, together with a redetermination of the structure of 3K₂S₂O₃·H₂O.     

Relationship between the electronic structures of the - {\rm O}{\rm H}, - {\rm N}{\rm H}_2 ,{}_/^\backslash CO, - NO_2 , = CH_2 , and{}_{//}^\backslash CH fragments and the local symmetry of each fragment in a molecule

Institute of Biochemistry. Institute of Physics, Academy of Sciences of the Lithuanian SSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 31, No. 3, pp. 24–31, May–June, 1990.     

在ADC(2)水平上通过从头算非绝热动力学方法模拟硝酸甲酯的光解（英文）

在ADC(2)水平上通过轨线面跳跃方法模拟了硝酸甲酯的非绝热动力学.结果证实该体系存在快速的非绝热动力学过程,导致了体系回到电子基态.当动力学从S₁和S₂电子态开始时,光解产物是CH₃O+NO₂,这个发现与实验研究的结果以及更高精度的XMS-CASPT2水平上模拟出的结果一致.在ADC(2)水平上,当动力学从S₃态开始时,光解产物依然是CH₃O+NO₂.该研究表明:ADC(2)方法可用于研究硝酸甲酯在长波下的光解机理,然而无法用于理解其在短波段下的光解动力学.本文为在ADC(2)水平上处理类似化合物的光诱导过程提供了有价值的信息.     

The synthesis, structure and ethene polymerization activity of octahedral heteroligated (salicylaldiminato)(β-enaminoketonato)titanium complexes: The X-ray crystal structure of {3-Bu-2-(O)C6H3CHN(Ph)}{(Ph)NC(Me)C(H)C(Me)O}TiCl2

Treatment of the mono(salicylaldiminato)titanium complexes {3-Bu^t-2-(O)C₆H₃CHN(Ar)}TiCl₃(THF) (Ar = C₆H₅, 2,4,6-Me₃C₆H₂ or C₆F₅) with the potassium β-enaminoketonates (C₆H₅)NC(CH₃)C(H)C(R)OK (R = CH₃, CF₃) yielded the first examples of heteroligated (salicylaldiminato) (β-enaminoketonato)titanium dichloride complexes. The complex {3-Bu^t-2-(O)C₆H₃CHN(C₆H₅)}{(C₆H₅)NC(CH₃)C(H)C(CH₃)O}TiCl₂ was structurally characterized by X-ray diffraction and has an orientation with trans-O,O,cis-Cl,Cl, cis-N,N distorted octahedral geometry. These complexes polymerize ethene when activated with MAO; the highest productivity, 5650 kg PE (mol metal)⁻¹ h⁻¹ atm⁻¹, was afforded by {3-Bu^t-2-(O)C₆H₃CHN(C₆F₅)}{(C₆H₅)NC(CH₃)C(H)C(CF₃)O}TiCl₂ at 60 °C.     

Electrogenerated Chemiluminescence Determination of Dopamine and Epinephrine in the Presence of Ascorbic Acid at Carbon Nanotube/Nafion‐Ru(bpy)$\rm{ {_{3}^{2+}}}$ Composite Film Modified Glassy Carbon Electrode

Based on the inhibition effect of dopamine and epinephrine on Ru(bpy) ‐tripropylamine electrogenerated chemiluminescence system, the excellent properties of carbon nanotube, and the cation permselectivity of Nafion film, an electrogenerated chemiluminescence inhibition method for determination of dopamine and epinephrine in the presence of ascorbic acid at carbon nanotube/Nafion‐Ru(bpy) composite film modified glassy carbon electrode was described. The results showed that the proposed method was sensitive and selective for the determination of dopamine and epinephine. The linear calibration range was from 1.6×10^?9 M to 3.2×10^?5 M and 5×10^?8 M to 6×10^?5 M for dopamine and epinephrine, respectively. 200‐fold excess of ascorbic acid did not interfere with the determination of 1 μM dopamine and epinephrine.