Mixed Ligation and Multinuclearity in Metal Sulfide Complexes of Geochemical Interest

9405432赫兹目前的许多研究都是为了了解痕量金属在缺氧水环境中的行为。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在数量级上是不确定的，因此远不如它们所应用的现场数据准确。在某些情况下，特别是多硫化物或硫醇配体，不存在数据。当有数据可用时，往往不确定所描述的物种是单核物种还是多核物种。这项建议要求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。在今后三年里，重点将放在：(A)解决关于砷和硫化锑络合物性质的争议(同时探索硫代砷和硫锑作为铜等金属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用于扩展先前关于锌和镉硫化物络合物的工作；(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以及确定黑色页岩中钼的形态的工作。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.