The sulfur containing ligand viz., thiosulfate is found to inhibit the Ag(I) catalyzed substitution of cyanide in hexacyanoferrate(II) by phenylhydrazine. The inhibitory effect of thiosulfate is attributed due to its tendency to form complexes with Ag(I), leading to the production of inhibitor-catalyst complexes. The reactions, followed spectrophotometrically in aqueous medium at 488 nm, was possible by the increase in absorbance of the cherry-red product, [Fe(CN)₅PhNHNH₂]^3- at pH 2.8 (±0.02), at 30 (±0.1) °C, and an ionic strength (μ) of 0.02 M (KNO₃). The linear calibration curves were obtained using the absorbance measured at different times (A_t) and thiosulfate concentrations under specified conditions. The calculated detection limit was 4.9 × 10^-7 M. The Michaelis-Menten constant (K_m) and equilibrium constants for the formation of complexes between catalyst and inhibitor (K_CI), and the catalyst and substrate (K_S) were computed from the kinetic data. A general mechanistic scheme is proposed for this reaction.

中文翻译：

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基于抑制作用的动力学测定痕量硫代硫酸盐

发现含硫的配体即硫代硫酸盐抑制了苯肼在六氰合铁酸酯（II）中的Ag（I）催化的氰化物取代。硫代硫酸盐的抑制作用归因于其倾向于与Ag（I）形成配合物的趋势，从而导致抑制剂-催化剂配合物的产生。在488 nm的水介质中用分光光度法进行反应，可能是通过增加樱桃红色产物[Fe（CN）₅ PhNHNH ₂ ] ^3-在pH 2.8（±0.02），30（±0.1）下的吸光度来实现的。）°C，离子强度（μ）为0.02 M（KNO ₃）。使用在不同时间测量的吸光度（A _t）和指定条件下的硫代硫酸盐浓度。计算出的检出限为4.9×10 ^-7M。催化剂和抑制剂形成配合物的米氏常数（K _m）和平衡常数（K _CI），以及催化剂和底物（K _S）的计算公式为动力学数据。提出了用于该反应的一般机理方案。