Kinetic and mechanistic investigations have been made on the displacement of the two aqua molecules from the complex 1 i.e., [Pt(2,2′-bipyridine)(H₂O)₂]²⁺ represented as {Pt(bpy)} (bpy = 2,2′-bipyridine) at pH 4.0. All the substitution reactions have been monitored at 264, 284 & 317 nm, where the spectral difference between the reactant and product is maximum. Two consecutive reaction steps have been observed for the substitution of aqua molecules with some bidentate N,N-donor ligands namely, dimethylglyoxime (L₁H), 1, 2-cyclohexanedionedioxime (L₂H) and α-furildioxime (L₃H) in ethanol-water medium using variable-temperature and stopped-flow spectrophotometry. Among the two steps, the former is ligand dependent and the later is ligand independent, where chelation is observed. All rate and activation parameters are consistent with associative substitution mechanisms. The thermodynamic parameters have been also calculated, which gives a negative DG⁰ value at all temperatures studied, supporting the spontaneous formation of an outer sphere association complex. The products of the reaction have been characterized with the help of IR and ESI-MS spectroscopic analysis.

中文翻译：

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乙醇-水介质中含双齿N，N-给体配体的新型铂（II）配合物的热力学和动力学研究

对两个水分子从复合物1即[Pt（2,2'-联吡啶）（H ₂ O）₂ ] ²⁺表示为{Pt（bpy）}（bpy ＝ 2，2′-联吡啶）在pH 4.0。已在264、284和317 nm处监测了所有取代反应，其中反应物和产物之间的光谱差异最大。已观察到两个连续的反应步骤，用一些二齿的N，N供体配体取代水分子，即二甲基乙二肟（L ₁ H），1，2-环己烷二酮二肟（L ₂ H）和α-呋喃二肟（L ₃H）在乙醇-水介质中使用变温和停止流分光光度法。在这两个步骤中，前者是配体依赖性的，而后者是配体依赖性的，其中观察到螯合。所有速率和激活参数均与关联取代机制一致。还计算出了热力学参数，该参数在所有研究温度下均给出了负DG ⁰值，支持了外球缔合复合物的自发形成。反应产物已通过IR和ESI-MS光谱分析进行了表征。