Sancho M I, Jubert A H, Blanco S E, Ferretti F H, Castro E A
Area de Química-Física, Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700 San Luis, Argentina.
Spectrochim Acta A Mol Biomol Spectrosc. 2007 Oct;68(2):387-93. doi: 10.1016/j.saa.2006.12.007. Epub 2006 Dec 8.
The influence of temperature and solvent effects on the stability of the complex formed by two molecules of 1,2-dihydroxybenzene and one molecule of AlCl3 were experimentally and theoretically studied, by means of UV spectroscopic methods and Density Functional Theory methods. The changes of the stability constant with the temperature were analyzed using the van't Hoff equation, while the variations with the permittivity of the reaction medium were explained with an equation proposed by us. The experimental and theoretical data obtained allowed proving that the increase in the hydrogen-bond donor ability of the solvents favors a higher thermodynamic stability of the reactants with respect to the complex and, therefore a decrease in the corresponding stability constant. The non-planar structure proposed for the 2:1 ligand-metal complex is coherent with the small batochromic shift experimentally observed. In the complex molecule, the planes containing the phenyl rings are tilted by approximately 89 degrees with each other. It was concluded that the complexation reaction is an endothermic process in which the solvent-solute interactions play an essential role.
通过紫外光谱法和密度泛函理论方法，对温度和溶剂效应 对由两分子1,2 - 二羟基苯和一分子三氯化铝形成的配合物稳定性的影响进行了实验和理论研究。利用范特霍夫方程分析了稳定常数随温度的变化，而用我们提出的一个方程解释了其随反应介质介电常数的变化。所获得的实验和理论数据证明，溶剂氢键供体能力的增加有利于反应物相对于配合物具有更高的热力学稳定性，因此相应的稳定常数降低。为2:1配体 - 金属配合物提出的非平面结构与实验观察到的小的红移相一致。在配合物分子中，包含苯环的平面彼此倾斜约89度。得出的结论是，络合反应是一个吸热过程，其中溶剂 - 溶质相互作用起着至关重要的作用。
