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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >EXAFS and Density Functional Study of Gold(I) Thiosulfate Complex in Aqueous Solution
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EXAFS and Density Functional Study of Gold(I) Thiosulfate Complex in Aqueous Solution

机译：硫代硫酸金（I）水溶液的EXAFS和密度泛函研究

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摘要

The gold thiosulfate complex, Au(S_2O_3)_2~(3-), has been studied using extended X-ray absorption fine structure (EXAFS) spectroscopy and high level quantum mechanical calculations, which include the effect of aqueous solvent via a dielectric continuum model. EXAFS measurements on Au(S_2O_3)_2~(3-) show gold coordinated by two sulfurs at 2.29 A. Density functional calculations, incorporating the effect of solvent using the COSMO method, show the 2-fold S coordination of Au to be linear in geometry. This computational approach is further employed to examine the conformational potential energy surface of the complex in aqueous solution. As expected from the significant deviation (108°) between the calculated conformation in aqueous solution and the observed crystal structure, internal rotation about the S-Au-S axis is facile: calculation predicts a rotational barrier in solution of less than 3 kcal/mol. Calculated Au-S bond dissociation energies indicate a strong metal-S bond in aqueous solution. Lower solution stability of Au(S_2O_3)_2~(3-) with respect to another thio gold complex, Au(SH)_2~-, is predicted in accord with measured overall stability constants. These calculations, together with our experimental observation that Au(S_2O_3)_2~(3-) decomposes at 393 K, support the view that gold transport by the thiosulfate complex of Au(I) may be restricted to ambient and moderate temperatures. This contrasts with the Au(I) thiolate complex which can mobilize gold at elevated temperature and pressure.
机译：使用扩展的X射线吸收精细结构（EXAFS）光谱和高级量子力学计算研究了硫代硫酸金络合物Au（S_2O_3）_2〜（3-），其中包括通过介电连续模型计算的水性溶剂效应。在Au（S_2O_3）_2〜（3-）上进行的EXAFS测量显示，金在2.29 A时与两个硫配位。密度函数计算（结合使用COSMO方法的溶剂影响）显示，Au的2倍S配位在线性几何。该计算方法被进一步用于检查该复合物在水溶液中的构象势能表面。正如从计算出的水溶液构型和观察到的晶体结构之间的显着偏差（108°）所预期的那样，围绕S-Au-S轴的内部旋转很容易：计算预测溶液中的旋转势垒小于3 kcal / mol 。计算出的Au-S键解离能表明水溶液中有很强的金属-S键。根据测得的整体稳定性常数，预测了Au（S_2O_3）_2〜（3-）相对于另一种硫金配合物Au（SH）_2〜-的较低溶液稳定性。这些计算结果以及我们在393 K上分解Au（S_2O_3）_2〜（3-）的实验观察结果，支持了Au（I）硫代硫酸盐络合物的金迁移可能仅限于环境温度和中等温度的观点。这与Au（I）硫醇盐络合物形成对比，后者可以在升高的温度和压力下动员金。

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