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A five-coordinated Fe(III) complex with the distorted trigonal bipyramidal configuration was synthesized by reactions of FeCl3•6H2O and 2-(2'-hydroxyphenyl)oxazoline (Hphox) as a bidentate ON donor oxazoline ligand. Complex [Fe(phox)2Cl] was fully characterized, including by single-crystal X-ray structure analysis. DFT calculations were accompanied with experimental results in order to obtain a deeper insight into the electronic structure and vibrational normal modes of complex. Oxidation of sulfides to sulfoxides in one-step was conducted by this complex as catalyst using urea hydrogen peroxide (UHP) in mixture of CH2Cl2/CH3OH (1:1) under air at room temperature. The results show that using this system in oxidation of sulfides, sulfoxides are obtained as the main products, together with variable amounts of sulfones (≼13%), depending on the nature of the substrate. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes a new, simple, sensitive, and selective catalytic–kinetic-spectrophotometric method for the determination of trace amounts of oxalate in vegetable and water samples. The method is based upon the catalytic effect of oxalate on the oxidation of crystal violet (CV) by dichromate in sulfuric acid media. The reaction was followed by measuring the decrease in absorbance of CV at 630nm (λ max of CV). The dependence of sensitivity on the reaction variables was studied and discussed. Under the optimum conditions, a fixed time procedure was used to obtain a linear calibration curve in the oxalate concentration ranges of 0.20–5.5μgmL−1 of oxalate. The calculated detection limit was 0.050μgmL−1. The relative standard deviations for ten replicate determinations of 0.40, 1.8, and 2.5μgmL−1 of oxalate were 6.0%, 2.5%, and 1.8%, respectively. The effect of the presence of various species commonly associated with real samples was also investigated. The proposed method was successfully applied for the determination of oxalate in vegetable and spiked water samples. [Copyright &y& Elsevier]

A flow injection (FI) system is described for the sequential determination of periodate and iodate based on their reaction with iodide at pH 3.5. Two sample plugs were injected into the same carrier stream sequentially. One injection is for the iodate determination and the other for the sum of iodate and periodate determination. For iodate determination, molybdate solution buffered at pH of 3.5 was used for selective masking of periodate. The influences of reagent concentrations were studied by a univariable method and the influence of FI manifolds was studied using univariable and simplex method. Periodate and iodate can be determined in the range of 0.050–5.0 and 0.050–10 μg/ml, respectively. The 3σ limit of detection was 0.030 and 0.050 μg/ml for periodate and iodate, respectively. The proposed method has been applied for the sequential determinations of periodate and iodate in water samples. [Copyright &y& Elsevier]