Rates of Oxygen Exchanges in the AlO4Al12(OH)12(H2O)247+(aq) Complex From 17O-NMR: A Guide to Mineral Surfaces

9814152 casy自然界中金属毒物的可用性通常由矿物表面的反应控制。表面光谱不能很容易地确定这些反应的原位速率，地球化学家也没有很好的模型来对粘土和其他矿物表面的氧的反应活性进行排序。这项研究将有助于更好地理解表面反应动力学，通过确定溶解Keggin分子[Al13O4(OH)24(H2O)127+(aq)]中的氧交换速率，该分子具有与重要土壤矿物质表面共同的结构特征。该分子由共用边的AlO6八面体和一个AlO4四面体组成。17O-NMR方法将用于测定溶解配合物中末端水和一个羟基位点的交换速率。然后，这些速率将用于估计在一些岩石和土壤矿物上类似位点的单原子步骤的反应性。其中一些反应是基本的；也就是说，它们按照分子尺度进行，可以用来测试表面反应的理论模型

9814152CaseyThe availability of metal toxicants in nature is commonly controlled by reactions at mineral surfaces. Surface spectroscopies cannot easily determine rates of these reactions in situ and geochemists have poor models for ranking reactivities of oxygens at the surface of clays and other minerals. This research will contribute to a better understanding of the kinetics of surface reactions by determining the rates of oxygen-exchange in a dissolved Keggin molecule [Al13O4(OH)24(H2O)127+(aq)] that has structural features in common with the surface of important soil minerals. The molecule consists of AlO6 octahedra that share edges and a single AlO4 tetrahedron. 17O-NMR methods will be employed to determine the exchange rates of terminal waters and one hydroxyl site in the dissolved complex. These rates will then be used to estimate the reactivity of similar sites at monoatomic steps on some rock and soil minerals. Some of these reactions are elementary; that is, they proceed as written on the molecular scale and can be used to test theoretical models of surface reactivities