Synthesis of a uranium(VI)-carbene: reductive formation of uranyl(V)-methanides, oxidative preparation of a [R2C═U═O]2+ analogue of the [O═U═O]2+ uranyl ion (R = Ph2PNSiMe3), and comparison of the nature of U(IV)═C, U(V)═C, and U(VI)═C double bonds

We report attempts to prepare uranyl(VI)- and uranium(VI) carbenes utilizing deprotonation and oxidation strategies. Treatment of the uranyl(VI)-methanide complex [(BIPMH)UO(2)Cl(THF)] [1, BIPMH = HC(PPh(2)NSiMe(3))(2)] with benzyl-sodium did not afford a uranyl(VI)-carbene via deprotonation. Instead, one-electron reduction and isolation of di- and trinuclear [UO(2)(BIPMH)(μ-Cl)UO(μ-O){BIPMH}] (2) and [UO(μ-O)(BIPMH)(μ(3)-Cl){UO(μ-O)(BIPMH)}(2)] (3), respectively, with concomitant elimination of dibenzyl, was observed. Complexes 2 and 3 represent the first examples of organometallic uranyl(V), and 3 is notable for exhibiting rare cation-cation interactions between uranyl(VI) and uranyl(V) groups. In contrast, two-electron oxidation of the uranium(IV)-carbene [(BIPM)UCl(3)Li(THF)(2)] (4) by 4-morpholine N-oxide afforded the first uranium(VI)-carbene [(BIPM)UOCl(2)] (6). Complex 6 exhibits a trans-CUO linkage that represents a [R(2)C═U═O](2+) analogue of the uranyl ion. Notably, treatment of 4 with other oxidants such as Me(3)NO, C(5)H(5)NO, and TEMPO afforded 1 as the only isolable product. Computational studies of 4, the uranium(V)-carbene [(BIPM)UCl(2)I] (5), and 6 reveal polarized covalent U═C double bonds in each case whose nature is significantly affected by the oxidation state of uranium. Natural Bond Order analyses indicate that upon oxidation from uranium(IV) to (V) to (VI) the uranium contribution to the U═C σ-bond can increase from ca. 18 to 32% and within this component the orbital composition is dominated by 5f character. For the corresponding U═C π-components, the uranium contribution increases from ca. 18 to 26% but then decreases to ca. 24% and is again dominated by 5f contributions. The calculations suggest that as a function of increasing oxidation state of uranium the radial contraction of the valence 5f and 6d orbitals of uranium may outweigh the increased polarizing power of uranium in 6 compared to 5.     

Ru(bipy)2+3/Ru(phen)2+3-C2O2-4-CeⅣ化学发光反应动力学模型的研究

根据Ru(bipy)2+3/Ru(phen)2+3-C2O2-4-CeⅣ(bipy=2,2′-联吡啶,phen=1,10-邻菲咯啉)化学发光反应建立了该化学发光反应的动力学模型,根据模型计算出该反应的发光强度-反应时间曲线上升及下降阶段的反应速率常数、发光强度最大值及其出现的时间等.发光强度最大值及发光强度-反应时间曲线下的面积均可用于定量分析.     

Complex formation between Ru(η(6)-p-cym)(H2O)3]2+ and (O,O) donor ligands with biological relevance in aqueous solution

The interaction between [Ru(η(6)-p-cym)(H(2)O)(3)](2+) and (O,O) type chelators with different basicity of the donor atoms was studied using combined pH-potentiometric, (1)H-NMR and ESI-TOF-MS techniques. The studied nine ligands are building blocks of reported complexes with antitumor activity or may model (O,O) donor serum components capable of interacting with the administered half-sandwich ruthenium(II) type drug. Composition and stability constants of the [Ru(η(6)-p-cym)(O,O)Y] type species (Y: H(2)O or OH(-)) were determined (T = 25.0 °C; I = 0.20 M (KCl)) and the metal ion binding strengths of the ligands are discussed. It was found that ligands with two low basicity O donors (oxalic and cyclobutane-1,1-dicarboxylic acid) bind the metal ion at acidic conditions but are not able to prevent the hydrolysis at physiologically relevant conditions. Ligands with one low and one high basicity O donor (lactic and salicylic acid) are weak binders for Ru(η(6)-p-cym)(H(2)O)(3)](2+). Pyrone or pyridinone based ligands are capable of binding the metal ion over a wide pH range and no hydrolysis product is detectable at pH = 7.4. The obtained speciation models may help in the rationalization of the biological activity of such complexes and provide a deeper insight into the solution behaviour of half-sandwich Ru(II) complexes with potential anticancer activity.     

Fe(IV)═O(TBC)(CH3CN)]2+: comparative reactivity of iron(IV)-oxo species with constrained equatorial cyclam ligation

[Fe(IV)═O(TBC)(CH(3)CN)](2+) (TBC = 1,4,8,11-tetrabenzyl-1,4,8,11-tetraazacyclotetradecane) is characterized, and its reactivity differences relative to [Fe(IV)═O(TMC)(CH(3)CN)](2+) (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) are evaluated in hydrogen atom (H-atom) abstraction and oxo-transfer reactions. Structural differences are defined using X-ray absorption spectroscopy and correlated to reactivities using density functional theory. The S = 1 ground states are highly similar and result in large activation barriers (~25 kcal/mol) due to steric interactions between the cyclam chelate and the substrate (e.g., ethylbenzene) associated with the equatorial π-attack required by this spin state. Conversely, H-atom abstraction reactivity on an S = 2 surface allows for a σ-attack with an axial substrate approach. This results in decreased steric interactions with the cyclam and a lower barrier (~9 kcal/mol). For [Fe(IV)═O(TBC)(CH(3)CN)](2+), the S = 2 excited state in the reactant is lower in energy and therefore more accessible at the transition state due to a weaker ligand field associated with the steric interactions of the benzyl substituents with the trans-axial ligand. This study is further extended to the oxo-transfer reaction, which is a two-electron process requiring both σ- and π-electron transfer and thus a nonlinear transition state. In oxo-transfer, the S = 2 has a lower barrier due to sequential vs concerted (S = 1) two electron transfer which gives a high-spin ferric intermediate at the transition state. The [Fe(IV)═O(TBC)(CH(3)CN)](2+) complex is more distorted at the transition state, with the iron farther out of the equatorial plane due to the steric interaction of the benzyl groups with the trans-axial ligand. This allows for better orbital overlap with the substrate, a lower barrier, and an increased rate of oxo-transfer.     

Ru(bipy)2+3-Ce(Ⅳ)化学发光体系检测速尿的研究

基于速尿对三(2, 2′-联吡啶)钌(Ⅱ)[Ru(bipy)2+3]-Ce(Ⅳ)化学发光体系发光的增强作用,建立了一种化学发光直接检测速尿的新方法.在优化的实验条件下,该方法的线性范围和检出限分别为5.0×10-3～1.5 mg/L和4.0×10-3 mg/L,对含速尿0.50 mg/L的溶液平行测定11次,相对标准偏差(RSD)为5.0 %.将其应用于呋塞米片剂样品中速尿含量的测定,结果满意.     

氢原子在Ru(0001)和Ru(1010)面上吸附扩散势能面的结构

本文构造了H-Ru相互作用的五参数Morse势,用经典的对势方法研究了氢原子在Ru(0001)和Ru(1010)面上的吸附和扩散,得到了氢原子在两个表面上的吸附位、吸附几何、结合能及本征振动等数据与实验结果符合得很好;同时研究了两个体系的吸附扩散势能面结构。     

(XY)12 (X═B, Al; Y═P)团簇的结构与稳定性

采用B3LYP/6-31G*方法, 对(XY)₁₂ (X═B, Al; Y═P)笼状团簇的同分异构体进行优化, 筛选出能量最低的构型. 讨论它们的几何构型、HOMO-LUMO能隙、生成焓、核独立化学位移(NICS)和自由能. 得到(BP)₁₂和(AlP)₁₂团簇的最稳定构型均为具有T_h对称性的四、六元环组成的笼, 亚稳态结构中含有五元环.     

Thermodynamics of Formation of Ru(III) and Ru(IV)-μ-Peroxo Complexes

Abstract

Reaction of one half and one equivalents of H₂O₂ with K[Ru^III(pdta-H)Cl].2H₂O gives rise to the μ-peroxo complexes [Ru^III (pdta-H)]₂H₂O₂ and [Ru^IV(pdta-H)]₂O₂, respectively. Equilibrium constants for the formation of the various peroxo species were determined between pH 3-11, in the temperature range 283-313 K and with μ = 0.10 M in KC1. The existence of the various peroxo species was substantiated by potentiometry, spectrophotometry and electrochemical studies. Thermodynamic quantities associated with the formation of the (pdta)Ru^III and (pdta)Ru^IV-μ-peroxo species and their hydrolysis products are reported.     

Application of the Ru(bipy)2(dpp)2+ / C2O4 2− electrochemiluminescence reaction to the determination of phenol

The electrochemiluminescence (ECL) of the ruthenium di(2,2′-bipyridine)- (4,7-diphenyl-1,10-phenanthroline) complex (Ru-bipy-dpp) produced on a glassy carbon electrode was studied by cyclic voltammetry. The anodic oxidation of Ru-bipy-dpp produces ECL in the presence of oxalate in oxygen-free aqueous solutions. Threefold ECL efficiencies were obtained for Ru-bipy-dpp relative to Ru(bipy)₃ as a standard. The ECL of Ru-bipy-dpp is quenched by both oxygen and phenol. The luminescence intensity was proportional to the concentration of phenol in the range of 5–100 μM. At a phenol concentration of 100 μM, the ECL of Ru-bipy-dpp peaking at 597 nm was completely quenched. Correspondence: Dan Xiao, College of Chemistry and Chemical Engineering, Sichuan University, Chengdu 610065, P.R. China     

Ru(phen)2+3-Ce(Ⅳ)化学发光体系检测吲哚乙酸的研究

基于吲哚乙酸(IAA)对三(1, 10-菲咯啉)钌(Ⅱ)[Ru(phen)2+3]-Ce(Ⅳ)化学发光体系的发光增强作用,建立了一种化学发光直接检测IAA的新方法.在优化的实验条件下,该方法的线性范围为5.0×10-3 ～2.0 μg·mL-1,检出限为2×10-3μg·mL-1 ;对含0.50 μg·mL-1IAA的溶液平行测定11次的相对标准偏差(RSD)为5.5%.方法用于合成样品中IAA含量的测定,结果满意.本文还对可能的化学发光机理进行了探讨.     

Ethylene addition to Ru(CH2)(O)3 – A theoretical study

Quantum chemical calculations using density functional theory (B3LYP) were carried out to elucidate the reaction pathways for ethylene addition to the ruthenium compound RuO₃CH₂. These investigations show that the parent compound is relatively unstable and its rearrangement gives access to very diverse isomers and addition products with comparable relative energies and reaction barriers. The results are compared to our previous study on the analogous osmium system OsO₃CH₂ and we show that reactivity of both compounds towards ethylene is quite similar. In both cases, the [3 + 2]_C,O cycloaddition pathway is preferred kinetically and thermodynamically. The exothermicity (–68.8 kcal/mol) of this reaction is higher for the ruthenium system than for the osmium homologue. While this pathway is unrivaled for the osmium system, the [3 + 2]_O,O cycloaddition pathway is able to compete kinetically for the ruthenium system.     

Characterization of a high-spin non-heme Fe(III)-OOH intermediate and its quantitative conversion to an Fe(IV)═O complex

We have generated a high-spin Fe(III)-OOH complex supported by tetramethylcyclam via protonation of its conjugate base and characterized it in detail using various spectroscopic methods. This Fe(III)-OOH species can be converted quantitatively to an Fe(IV)═O complex via O-O bond cleavage; this is the first example of such a conversion. This conversion is promoted by two factors: the strong Fe(III)-OOH bond, which inhibits Fe-O bond lysis, and the addition of protons, which facilitates O-O bond cleavage. This example provides a synthetic precedent for how O-O bond cleavage of high-spin Fe(III)-peroxo intermediates of non-heme iron enzymes may be promoted.     

Study on Coupled Chemiluminescene Reaction of Ru(l,10-PhenanthroIine)32+-Methanol-Ce(Ⅳ)

It was reported that some hydroxyl/carbonyl carboxylic acids can enhance the chemiluminescence light emission intensity of Ru(phen)₃²⁺(Phen=1,10-phenanthroline) with Ce(Ⅳ). Further studies showed that methanol can also enhance the light emission intensity. In sulfuric acid medium, methanol was oxidized by eerie sulfate, the rate of oxidation depended directly on the concentration of cerium(Ⅳ) and methanol. The reaction rate changes inversely with sulfuric acid. The reaction occurs without the intermediate formation of a complex.     

A diruthenium soft ferromagnet showing T(c) = 3.0 K: Mn4(H2O)16H[Ru2(CO3)4]2[Ru2(CO3)4(H2O)2]·11H2O

A three-dimensional CO(3)(2-)-bridged Mn(II)-Ru(2)(II,III) complex, Mn(4)(H(2)O)(16)H[Ru(2)(CO(3))(4)](2)[Ru(2)(CO(3))(4)(H(2)O)(2)]·11H(2)O (1), was synthesized by self-assembling Ru(2)(CO(3))(4)(3-) paddle-wheel precursors and Mn(2+) cations. It contains an unprecedented layer [Ru(2)(CO(3))(4)](n)(3n-) with (4,4) network. The ferromagnetic coupling between spin centers results in ordering below 3.0 K.     

Bis[tetraruthenium(IV)]-containing polyoxometalates: [{Ru(IV)4O6(H2O)9}2Sb2W20O68(OH)2]4- and [{Ru(IV)4O6(H2O)9}2{Fe(H2O)2}2{β-TeW9O33}2H]-

The reaction of [Sb(2)W(22)O(74)(OH)(2)](12-) and [Fe(4)(H(2)O)(10)(β-TeW(9)O(33))(2)](4-) with (NH(4))(2)[RuCl(6)] in aqueous solution resulted in the novel ruthenium(IV)-containing polyanions [{Ru(IV)(4)O(6)(H(2)O)(9)}(2)Sb(2)W(20)O(68)(OH)(2)](4-) and [{Ru(IV)(4)O(6)(H(2)O)(9)}(2){Fe(H(2)O)(2)}(2){β-TeW(9)O(33)}(2)H](-), exhibiting two cationic, adamantane-like, tetraruthenium(IV) units {Ru(4)O(6)(H(2)O)(9)}(4+) bound to the respective polyanion in an external, highly accessible fashion.     

具夹心结构(Bu4N)7H3［Ru2O(H2O)2(γ-SiW10O36)2］的合成及表征

以γ-［SiW10O36］8-及桥联的K4Ru2OCl10为原料,合成了(Bu4N)7H3［Ru2O(H2O)2(γ-SiW10O36)2］,经红外光谱、电子光谱、顺磁共振、磁化率、循环伏安和核磁共振等的表征,证明标题化合物为两聚夹心结构. 其中,γ-［SiW10O36］8-结构保持不变,填入的Ru—O—Ru为直线型,均保持了原料的基本构型.     

Ru(phen)3 2+-SDBS-KMnO4化学发光体系检测半胱氨酸的研究

在20mmol·L-1硫酸-1.2mmol.L-1十二烷基苯磺酸钠(SDBS)介质中,半胱氨酸可以增强三(1,10-菲咯啉)钌(Ⅱ)[Ru(phen)32+]-KMnO4化学发光体系的发光强度.基于此,建立了一种化学发光直接检测半胱氨酸的新方法.在优化的实验条件下,该方法的线性范围和检测限分别为2.5×10-2-2.0μg·mL-1和2.1×10-2μg·mL-1,对11份含半胱氨酸0.5μg·mL-1的溶液平行测定的相对标准偏差(R.S.D.)为5.3%.将其用于合成样品中半胱氨酸含量的测定,结果令人满意.并提出了可能的化学发光机理.     

Ru(bpy)2+3 在MCM-48中的组装及其发光性质

无机微孔晶体具有均一的孔径和特殊的孔道及笼结构, 已被证明是一类优良的功能组装载体. 早期合成的微孔沸石分子筛晶体的孔道直径一般小于1 nm, 很难直接组装尺寸较大的功能分子, 因而Ru(bpy)2+3在Na-Y沸石分子筛中的组装只能采取所谓的"瓶中造船"方法, 该方法的缺点是反应过程较复杂, 反应条件较苛刻, 容易产生杂质且无法除去.     

Ru(phen)32+-SDBS-KMnO4化学发光体系检测还原型谷胱甘肽的研究

当硫酸介质中有阴离子表面活性剂十二烷基苯磺酸钠(SDBS)存在时,还原型谷胱甘肽(G-SH)可以增强三(1,10-菲咯啉)钌(Ⅱ)[Ru(phen)32+]-KMnO4化学发光体系的发光强度.基于此,建立了一种化学发光直接检测G-SH的新方法.在优化的实验条件下,该方法的线性范围和检出限分别为5.0×10-2～2.0μg·mL-1和3.5×10-2μg·mL,对1.0μg·mL-1的G-SH溶液平行测定11次的相对标准偏差(RSD)为5.8%.将其用于合成样品中G-SH含量的测定,结果满意.并提出了可能的化学发光机理.