Encapsulating ruthenium and osmium with tris(2-aminoethyl)amine based tripodal ligands

The reaction of a series of tripodal ligands, H₃L^1,2 and L^3-6, with [M(PPh₃)₂Cl₂] (M = Ru, Os) affords a family of coordination cage compounds of the type [M^IIIL^1,2] (1-4) or [M^IIL^3-6](BPh₄)₂ (5-12). The Schiff base ligands (H₃L¹, L³, L⁵) have been synthesized by condensation of tris(2-aminoethyl)amine with salicylaldehyde, pyridine-2-aldehyde and 1-methyl-2-imidazolecarboxaldehyde. These ligands were further reduced and subsequently methylated to form the new ligands (H₃L², L⁴, L⁶). Single crystal X-ray diffraction studies of 1 and 2 show that the tripodal ligand wraps around the metal center as a hexadentate ligand to form a cage. All the synthesized compounds have been thoroughly characterized by ESI-MS, FT-IR, UV-Vis and NMR spectroscopic methods. To the best of our knowledge, this is the first ever report of osmium complexes with tris(2-aminoethyl)amine based tripodal ligands. DFT calculations were performed to obtain geometry optimized structures of all the other complexes (3-12).     

顺序注射阻抑动力学光度法测定环境水样中的间苯二酚

在酸性条件下,利用间苯二酚能抑制罗丹明B和溴酸根反应速率的原理,联用顺序注射技术建立了非平衡态快速测定痕量间苯二酚的新方法.优化了顺序注射流路参数、试剂用量,考察了共存物的影响.在最佳条件下,该法测定间苯二酚的线性范围为0.20～3.00 μg/mL,检出限为0.09 μg/mL,每小时可测定40个样.     

A simple and high sensitive spectrophotometric method for ultra trace determination of ruthenium with its catalytic effect on the oxidation of pyronin B by periodate

A new simple, selective, high sensitive and rapid method has been developed for spectrophotometric determination of ultra trace amounts of ruthenium based on its catalytic effect on the oxidation of pyronin B by periodate at lambdamax=555 nm. The described method is able to quantify ruthenium in the range of 0.1-100 ng ml-1 (r=0.9973), with a detection limit (S/N=3) of 0.036 ng ml-1. Under optimum conditions, this procedure has been successfully applied to determine the trace levels of ruthenium in the environmental and biological samples. The precision, expressed as relative standard deviation of three measurements, is better than 2.44%.     

Polymeric cofactors which accelerate homogeneous rhodium(I) and ruthenium(II) catalyzed hydrogenations of alkenes

Polymeric reagents prepared by exchanging silver(I) for H⁺ on a macroreticular polystyrene sulfonate ion exchange resin are shown to be capable of selectively absorbing triphenylphosphine from solutions of triphenylphosphine complexes of rhodium(I) and ruthenium(II). Absorption of triphenylphosphine during alkene hydrogenations catalyzed by RhCl(PPh₃)₃, RuCl₂(PPh₃)₃ and RuHCl(PPh₃)₃ led to increased hydrogenation rates in hydrogenation of 1-hexene and other alkenes. Addition of this silver(I) polystyrene sulfonate to alkene hydrogenations catalyzed by HRh(CO) (PPh₃)₃, RuH₂(PPh₃)₃ and RuH(OCOCH₃) (PPh₃)₃ also led to modest rate accelerations. Catalyst activations seen in these alkene hydrogenations were shown to be due in some cases to triphenylphosphine absorption. In other cases, HCl or HCl plus triphenylphosphine absorption was responsible for the formation of a more active catalyst solution.     

Highly efficient oxidation of alcohols using Oxone(R) as oxidant catalyzed by ruthenium complex under mild reaction conditions

Aromatic and alkyl alcohols were oxidized to the corresponding aldehydes or ketones at room temperature with high conversion and selectivity using Oxone (2KHSO5·KHSO4·K2SO4) as oxidant catalyzed by ruthenium complex Quin-Ru-Quin (where Quin = 8-hydroxyquinoline). The reaction time is very short and the preparation of complex is simple. 2008 Zi Qiang Lei. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.     

Simple and economical conversion of organic compounds with H2O2 catalyzed by ruthenium (III) chloride

Six aromatic aldehydes, two hydrocarbons, one cycloalcohol and one aromatic alcohol, viz. benzaldehyde, p‐chlorobenzaldehyde, cinnamaldehyde, 4‐methoxybenzaldehyde, o‐hydroxybenzaldehyde, 4‐hydroxy, 3‐methoxybenzaldehyde, anthracene, phenanthrene, cyclohexanol and benzyl alcohol dissolved in acetic acid, were oxidized in quantitative to moderate yields by 50% H₂O₂ in the presence of traces of RuCl₃ (substrate:catalyst ratio 85 400 to 387 500:1). Conditions for highest yields, under most economical conditions, were obtained. Higher catalyst concentrations decreased the yield. Oxidation in aromatic aldehydes is selective at aldehydic group only, and other groups remain unaffected. The extent of oxidation in phenanthrene depends on temperature or the relative amount of substrate or both. In this new, simple and economical method, which is environmentally safe and requires less time, oxocentered carboxylate species of ruthenium (III) probably catalyze the oxidation. Copyright © 2005 John Wiley & Sons, Ltd.     

Selective determination of acenaphthylene by flow injection analysis with tris(2,2'-bipyridine)ruthenium(II) chemiluminescence detection

A simple, rapid flow injection chemiluminescence (FI-CL) method has been developed for selective determination of acenaphthylene (ACY), based on the CL produced in the reaction of tris(2,2′-bipyridine)ruthenium(III) (Ru(bipy)₃³⁺) and ACY in an acidic buffer solution. Under the optimum experimental conditions, the calibration curve was linear over the range 5.0 × 10⁻³ to 4.0 × 10⁻⁷ mol L⁻¹ for ACY. The detection limit (S/N = 3) was 2.0 × 10⁻⁷ mol L⁻¹ and the relative standard deviation of 10 replicate measurements was 2.3% for 5.0 × 10⁻⁵ mol L⁻¹ of ACY. Selectivity of CL reaction of ACY from other 15 polycyclic aromatic hydrocarbons (PAHs) was investigated by flow injection method. The method was applied to determine the ACY content in soil.     

K4[Fe(CN)6]-K3[Fe(CN)6]体系催化分光光度法测定痕量汞

建立了一种测定痕量汞的催化分光光度新方法,它是基于汞能催化亚铁氰化钾分解生成Fe2 ,生成的Fe2 又与铁氰化钾反应生成兰色胶体溶液.方法的相对标准偏差≤5.3%,回收率为98.8%～104.8%之间,检出限为9.8×10-7 g/L;线性范围为0～0.050 μg/mL.     

Structural studies on ruthenium(II) complexes used in interphase catalysis for the hydrogenation of ketones

Structural studies were performed on catalytically active ruthenium(II) complexes used in interphases, by means of XAFS spectroscopy. The EXAFS investigations indicate that the complexes retain their structural integrity when they are embedded on polysiloxane matrices to form stationary phase materials. The AXAFS studies reveal that the variations in the catalytic activity of the complexes with different ligands can be correlated to the differences in the electronic structure around the active ruthenium center. The EXAFS investigations show that, in asymmetric transfer hydrogenation reactions catalysed by ruthenium(II) complexes, the co‐catalyst plays a crucial role not only in enhancing the catalytic activity, but also in determining the structure of the intermediate species. Copyright © 2007 John Wiley & Sons, Ltd.     

Kinetic method for determination of nanogram amounts of copper(II) by its catalytic effect on hexacynoferrate(III)-citric acid indicator reaction

This paper describes a highly sensitive, selective catalytic-kinetic-spectrophotometric method for the determination of copper(II) concentration as low as 6 ng ml⁻¹. The method is based on the catalytic effect of copper(II) on the oxidation of citric acid by alkaline hexacyanoferrate(III). The reaction was followed by measuring the decrease in absorbance of hexacyanoferrate(III) at 420 nm (λ_max of [Fe(CN)₆]³⁻, ∈ = 1020 dm³ mol⁻¹ cm⁻¹). The dependence of rate of the indicator reaction on the reaction variables has been studied and discussed to propose a suitable mechanism to get a relation between the reaction rate and [Cu²⁺]. A fixed time procedure has been used to obtain a linear calibration curve between the initial rate and lower [Cu²⁺] or log[Cu²⁺] in the range 1 × 10⁻⁷ to 4 × 10⁻⁴ mol l⁻¹ (6.35-25,400 ng ml⁻¹). The detection limit has been calculated to be 4 ng ml⁻¹. The maximum average error is 3.5%. The effect of the presence of various cations, commonly associated with copper(II) and some anions has also been investigated and discussed. The proposed method is sensitive, accurate, rapid and inexpensive compared to other techniques available for determination of copper(II) in such a large range of concentration. The new method has been successfully applied for the determination of copper(II) in various samples.     

Sensitive spectrofluorimetric determination of ruthenium at nanotrace levels using 2-(α-pyridyl) thioquinaldinamide [PTQA]

A new spectrofluorimetric method for the determination of ruthenium with nonfluorescent 2-(α-pyridyl) thioquinaldinamide (PTQA) is described. The oxidative reaction of Ru(III) upon PTQA gives oxidised fluorescent product (λ_ex(max)=347 nm; λ_em(max)=486 nm). The sensitivity of the fluorescence reaction between ruthenium and PTQA is greatly increased in the presence of Fe (III). The reaction is carried out in the acidity range 0.01–0.075 M H₂SO₄. The influence of reaction variables is discussed. The range of linearity is 1–400 μg l⁻¹ Ru(III). The standard deviation and relative standard deviation of the developed method are ±1.210 μg l⁻¹ Ru (III) and 2.4%, respectively (for 11 replicate determinations of 50 μg l⁻¹ Ru (III)). The effect of interferences from other metal ions, anions and complexing agents was studied; the masking action is discussed. The developed method has been successfully tested over synthetic mixtures of various base metals and platinum group metals, synthetic mixtures corresponding to osmiridium, certified reference materials in spiked conditions and rock samples.     

Kinetic determination of organosulphur ligands by inhibition: Trace determination of cysteine and maleonitriledithiolate (MNDT)

Some organosulphur ligands have been found to inhibit the mercury(II) catalyzed substitution of cyanide in hexacyanoferrate(II) by N-methylpyrazinium ion (Mpz⁺). The inhibitory effect is due to the binding tendency of catalyst Hg²⁺ with these inhibitors. This effect has been used as a basis to develop a kinetic method for the determination of trace amounts of two organosulphur ligands viz. cysteine and MNDT. The reaction was followed spectrophotometrically at 655 nm by measuring the decrease in absorbance of the product [Fe(CN)₅Mpz]²⁻. The influence of the reaction variables has also been studied. A general mechanistic scheme of the indicator reaction system including the role of inhibitor has been proposed and applied to determine the organosulphur ligands. Under the selected experimental conditions cysteine and MNDT have been determined in the range of 2–20 × 10^− 7 M and 5 × 10^− 8 M to 12 × 10^− 7 M respectively in various aqueous samples. The analytical concentration range depends upon the amount of Hg²⁺ present in the indicator reaction and also on the stability of the Hg²⁺-inhibitor complex in question. Under specified conditions, the detection limit for cysteine and MNDT are 2 × 10^− 7 M and 5 × 10^− 8 M respectively. The influences of possible interference by major amino acids, on the determination of cysteine and their limits have been investigated.