Mixed Ligation and Multinuclearity in Metal Sulfide Complexes of Geochemical Interest

9405432 Helz目前的研究主要是为了了解微量金属在缺氧水生环境中的行为。 这些研究产生了对含有还原硫配体的金属络合物的化学计量和稳定性的准确数据的需要。 许多现有的稳定常数是不确定的数量级，因此远不如他们所应用的现场数据准确。 在某些情况下，特别是对于多硫化物或硫醇配体，没有数据存在。 当数据可用时，通常不确定所描述的物种是单核还是多核。 该提案要求支持继续研究金属硫化物和多硫化物络合物的稳定性。 我们的方法结合了传统的溶液化学和EXAFS光谱。 在未来三年，重点将放在（a）解决有关砷和锑硫化物络合物性质的争议（同时探索硫代砷和硫代锑作为金属如Cu的络合配体的可能重要性）（B）开发连续流动反应器方法并将其应用于扩展先前关于Zn和Cd硫化物络合物的工作，以及（c）继续目前关于硫代钼酸盐作为地球化学重要配体的作用的工作，并确定黑色页岩中钼的形式。 在镉和锌硫化物的实验中，将探索测量表面能的可能性。

9405432 Helz Much current research is directed toward understanding the behavior of trace metals in anoxic aquatic environments. These studies create a need for accurate data on the stoichiometry and stability of metal complexes containing reduced sulfur ligands. Many existing stability constants are uncertain at the order of magnitude level and thus far less accurate than the field data to which they are applied. In some cases, especially for polysulfide or thiol ligands, no data exist. When data are available, it is often uncertain whether the species described are mononuclear or polynuclear. This proposal request support to continue research on the stabilities of metal sulfide and polysulfide complexes. Our approach combines traditional solution chemistry and EXAFS spectroscopy. In the coming three years, emphasis will be placed on (a) resolving the controversy concerning the nature of arsenic and antimony sulfide complexes (while at the same time exploring the possible importance of thioarsenic and thioantimony as complexing ligands for metals like Cu) (b) developing a continuous flow reactor method and applying it to extend previous work on Zn and Cd sulfide complexes and (c) continuing current work on the role of thiomolybdates as geochemically important ligands and determining the form of Mo in black shales. In the experiments on Cd and Zn sulfides, the possibility of measuring surface energies will be explored.