Complexing equilibria and redox potentials in the system Ag(II)/Ag(I)-1,10-phenanthroline in propylene carbonate

Predominance areas of various equilibria were identified and complex formation constants of Ag(I) with 1,10-phenanthroline were determined as well as the solubility product of the complex salt for Ag(phen)₂ClO₄ in propylene carbonate. The solubility product of AgNO₃ in propylene carbonate was estimated. The value of the formal potential of the system Ag(phen) ₂ ²⁺ /Ag(phen) ₂ ⁺ inPC was determined by chronovoltammetry. Differences in the stability of analogous complexes in water andPC are discussed.

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Die Gleichgewichtskonstante der Komplexierung und die Redoxpotentiale im System Ag(II)/Ag(I)-1,10-Phenantrolin in Propylencarbonat

Zusammenfassung Die Gebiete der Dominanz der einzelnen Gleichgewichte, die Bildungskonstanten ₁ und ₂ der Komplexe Ag(I) mit 1,10-Phenantrolin und der Wert des Löslichkeitsproduktes Ag(phen)₂ClO₄ in Propylencarbonat wurden bestimmt. Das Löslichkeitsprodukt von AgNO₃ in Propylencarbonat wurde abgeschätzt. Die Werte des formalen Potentials des Systems Ag(phen) ₂ ²⁺ /Ag(phen) ₂ ⁺ inPC wurden mit Hilfe cyclischer Voltametrie ermittelt. Es wurden weiterhin die Unterschiede in der Stabilität analoger Komplexe in Wasser und in Propylencarbonat diskutiert.

     

纳米银掺杂二氧化硅复合颗粒的制备及表征

0引言金属纳米颗粒因其粒子尺寸小(1￣100nm),比表面积大,表面原子数多,表面能和表面张力随粒径的下降急剧增大而具有量子尺寸效应[1]、小尺寸效应[2]、表面效应[3]及宏观量子隧道效应[4]等,从而出现了不同于常规固体的新奇特性,如:光学性质、磁性质以及电磁学性质[5],使其在催化、信息存储及非线性光学等领域展示了广阔的应用前景[6]。虽然制备金属纳米颗粒的方法有很多[6],但是由于纳米尺寸的金属颗粒具有较高的表面能,容易发生聚集,所以如何保持其稳定性依旧是比较困难的问题。随着纳米科技的发展,人们正尝试用各种方法来解决这个问题:如…     

Ag／Al2O3选择性催化丙烯还原氮氧化物表面反应机理的原位红外光谱研究

 在富氧条件下Ag／Al2O3对以丙烯为还原剂选择性催化还原NOx的反应有很高的催化活性．本实验成功地利用原位红外光谱分析手段,在真实的催化反应条件下,探讨了丙烯选择性还原NOx的反应机理,证实了催化剂表面反应中间体Al－NCO和Ag－NCO虽在真空中稳定,但在实际反应条件下极为活泼．催化剂表面上R－ONO和R－NO2分解成NCO是整个反应的速度控制步骤．这一结论与在真空系统条件下对其反应机理的研究结果一致,证明了在这一反应体系中两种研究方法的相关性．同时本实验还从反应机理上探讨了催化剂的水蒸气中毒现象．水蒸气的存在阻碍了催化剂表面R－ONO和R－NO2的生成,并进一步阻碍了反应的速度控 制步骤,即R－ONO和R－NO2向Al－NCO和Ag－NCO的转化,但这是一种完全可逆的暂时中毒现象．结合相应的催化剂活性评价结果对表面反应机理进行了讨论．     

Synthesis and Crystal Structure of Ag2（admtrz）2（CF3CO2）2（admtrz=4—amino—3,5—dimethyl—1,2,4—triazole）

1 INTRODUCTION Transition metal complexes bridged by 1, 2, 4-triazole group can produce interesting structures and specific properties[1]. Many attempts have been made to synthesize a variety of complexes with paramagnetic centers by using such ligands, and their structures and magnetic properties have been characterized[2]. However, the polynuclear Ag(I) complexes bridged by 1, 2, 4-triazole have been poorly studied[3]. Recently, we have prepared a series of silver(I) triazole complex…     

Catalytic Spectrophotometric Determination of Ultratrace Amounts of Silver with Solubilizing Effect of Nonionic Surfactant

ＩｎｔｒｏｄｕｃｔｉｏｎＴｒｉａｚｅｎｅｒｅａｇｅｎｔｓａｒｅｉｎｔｅｒｅｓｔｉｎｇｂｅｃａｕｓｅｏｆｔｈｅｉｒｓｔｒｏｎｇｃｏｍｐｌｅｘａｔｉｏｎａｂｉｌｉｔｉｅｓｗｉｔｈｔｒａｎｓｉｔｉｏｎｍｅｔａｌｓ .1 6Ｈｏｗｅｖｅｒ,ｌｉｔｔｌｅｄｅｃｏｌｏｒａｔｉｏｎｏｆｔｈｅｍｃａｔａｌｙｚｅｄｂｙｓｉｌｖｅｒｉｏｎｈａｓｂｅｅｎｓｔｕｄｉｅｄｉｎａｎａｌｙｔｉｃａｌｃｈｅｍｉｓｔｒｙ .Ｍａｎｙａｎａｌ ｙｓｉｓｔｓｈａｖｅｒｅｐｏｒｔｅｄｔｈｅｕｓｅｏｆｃａｔａｌｙｔｉｃｒｅａｃｔｉｏｎｓｆｏｒｔ…     

Synthesis of a Tweezer—like Bis（Phenylthiapropoxy）calix[4]—arene as a Cation／π Enhanced Sensor for Ion—Selective Electrodes

Two novel 25,27-dihydroxy-26,28-bis(3-phenylthiapropxy)-calix[4]arene(3) and 25,27-dihydroxy-26,28-bis(3-phenylthiapropoxy)-5,11,17,23-tetra-tert-butylcalix[4] arene (4) were synthesized for the evaluation of their ion-selectivity in ion-selective electrodes(ISEs).ISEs based on 3 and 4 as neutral ionophores were prepared,and their selectivity coefficients for Ag^ (lg KAg,M^pot)were investigated against other alkali metal,alkaline-earth metal,aluminum,thallium(Ⅰ）,Lead and some transition metal ions using the separate solution method (SSM).These ISEs showed excellent Ag^ seletivity over most of the interfering cations examined,except for Hg^2 and Fe^2 having relative smaller interference(lg KAg,M^pot≤-2.1).     

Re-Evaluation of the Activity Coefficients of Aqueous Hydrochloric Acid Solutions up to a Molality of 2.0 Using Two-Parameter Hückel and Pitzer Equations. Part II. Results from 0 to 95°C

Simple two-parameter Hückel and Pitzer equations were used for the calculation of the activity coefficients of aqueous hydrochloric acid at temperatures 0–60°C up to a molality of 2.0 mol-kg^–1. The data obtained by Harned and Ehlers^(2,3) on galvanic cells without a liquid junction were used in the parameter estimations of these equations. These data consist of sets of measurements at the temperature intervals of 5°C. It was observed that all estimated parameters follow very simple equations with respect to temperature. They are either constant or depend linearly on the temperature. The values for the activity coefficient parameters calculated by these simple equations are recommended here. The recommended parameter values were tested by predicting the data of Gupta, Hills, and Ives,⁽⁵⁾ consisting of cell measurements from 5 to 45°C and molalities up to 1.0 mol-kg^–1, and the data of Bates and Bower,⁽⁴⁾ which extend to 95°C but measurements were only made on molalities less than about 0.1 mol-kg^–1. The activity coefficients obtained by the new equations were also compared to those calculated by the Pitzer equations with the parameter values determined by Saluja, Pitzer, and Phutela⁽⁶⁾ from calorimetric data. The agreement observed was excellent up to a molality of 1.5 mol-kg^–1 at temperatures from 0 to 60°C.     

Ag-mediated synthesis of six-membered N-heterocycles

Abstract

One of the highly emerging and an important aspect of organic chemistry is the metal catalyzed synthesis of heterocycles. The methods used earlier for the synthesis of heterocycles were significant in the organic synthesis and developing cost-effective, improved and facial methods were beneficial to construct the complex architectures. For the both stereoselective and regioselective synthesis of six-membered nitrogen containing heterocycles, cyclic reactions that are Ag-mediated have known to be very efficient. The present review covers the applications of Ag in the formation of six-membered nitrogen containing heterocycles.     

新型单膦配位羧酸银配合物的合成、表征及其热稳定性的研究(英)

0 IntroductionIn recent years, silver carboxylates have attractedmany interests, mostly because they are promisingcandidates in the growth of metal thin films via metal-organic chemical vapor deposition (MOCVD) tech-niques. These sliver compounds show low light sensi-tivity and relatively high thermal stability. Several ex-amples of bisphosphine ligands coordinated silver car-boxlylates have been reported[1￣4].Monophosphine coordinated silver complexes areexpected to have better volatility,…     

Superconductivity in copper, silver, and gold compounds

High-temperature superconductivity exists in layered, square-planar cuprates, but is almost absent in most other Cu(II) compounds and in most Ag(II) and Au(II) compounds. Valence state II is quite unusual in silver and gold and often disproportionates to valence states I and III ("negative-U compounds"). The two-electron difference in oxidation state is suggestive of electron pairing, a prerequisite for superconductivity. In the present paper the connection between disproportionation and geometrical structure on one hand and superconductivity on the other is discussed by using the accepted theory for mixed valence complexes. It is concluded that absence of superconductivity in gold and silver compounds can be connected to the instability of oxidation state II and the large difference in equilibrium geometry between oxidation states I and III.