Dept. Química Física I, Universidad Complutense de Madrid, Avda Complutense s/n, 28040 Madrid, Spain.
Phys Chem Chem Phys. 2009 Nov 14;11(42):9710-9. doi: 10.1039/b911457b. Epub 2009 Sep 8.
Nitric acid, hydrochloric acid and water can form stable aggregates with atmospheric implications, for instance at the surface of polar stratospheric clouds. The structure, stability and chemical properties of these ternary complexes are studied by means of high level theoretical calculations (hybrid DFT B3LYP method along with aug-cc-pVQZ basis set). From the many possible systems that these molecules could form, only 15 are found to yield stable structures, well characterized by a minimum in their potential energy surfaces. These aggregates are studied in detail. They can be collected in three families, according to the role played by each species in the different hydrogen bonding links that result and provide the basis for the stabilization of the clusters. Water and HCl can be H-donors to almost every O atom of HNO(3), which in turn can donate its H atom to the other two molecules. Two special cases are found, one in which H(2)O plays a central role, and another with a three-dimensional structure, in contrast to the basically planar frame of the other clusters. Bonding properties are investigated for the whole series using AIM methods. The elongation of the H-Cl bond as a consequence of the aggregate creation is inspected in detail, as it may provide a clue to the lability of this molecule with implications in atmospheric processes. The Gibbs free energy calculated for these clusters shows that some of them could form spontaneously in the range of temperatures of the stratosphere.
硝酸、盐酸和水可以与大气成分形成稳定的聚集体，例如在极地平流层云的表面。通过使用高级理论计算（混合 DFT B3LYP 方法和 aug-cc-pVQZ 基组）研究了这些三元配合物的结构、稳定性和化学性质。在这些分子可能形成的许多可能的体系中，只有 15 种被发现具有稳定的结构，其势能表面的最小值很好地说明了这一点。详细研究了这些聚集体。根据它们在不同氢键链接中所扮演的角色，可以将它们收集在三个家族中，这些氢键链接为簇的稳定提供了基础。水和 HCl 可以作为 H 供体与 HNO(3)的几乎每个 O 原子成键，而 HNO(3)反过来又可以将其 H 原子供体给其他两个分子。发现了两种特殊情况，一种是 H(2)O 起中心作用，另一种是具有三维结构，与其他聚集体的基本平面框架形成对比。使用 AIM 方法研究了整个系列的键合性质。详细检查了由于聚集体形成而导致的 H-Cl 键伸长，因为它可能为该分子在大气过程中的不稳定性提供线索。为这些聚集体计算的吉布斯自由能表明，其中一些在平流层的温度范围内可能会自发形成。
