Role of Metal Sulfides in Carbon-Heteroatom Bond Cleavage

科罗拉多大学博尔德分校化学系的Mary Rakowski-DuBois博士受到无机、生物无机和有机金属化学项目的支持，对含有硫化物配体的过渡金属配合物促进的C=O、C- s和C- n键裂解反应进行了研究。例如，在C=O的情况下，预计一氧化碳会插入到SH配体的SH键中，作为钼二聚体的桥。由此产生的甲酰基硫酯容易被氢还原裂解C=O键。这可以模拟一氧化碳转化为甲烷的第一步，这是一个通常不由过渡金属配合物促进的反应，这里通过与硫结合而不是与金属结合来促进。本研究为非均相硫化钼催化CO还原的机理提供了新的思路。在氢裂解C-N键的研究中，硫化金属配合物可作为商业HDN（加氢脱氮）过程中使用的非均相催化剂模型。除了上述反应外，还将制备含有Ir， Rh, Re， Mo和Mo- cr以及各种含硫和含氮配体的新型配合物。该项目有望为过渡金属配合物与小分子的反应提供洞见，这对于此类配合物作为多相和均相催化剂的使用具有重要意义。具体来说，这些研究可能为理解用于加氢脱氮的商业非均相催化剂的行为提供相关信息。

Dr. Mary Rakowski-DuBois of the Chemistry Department, University of Colorado at Boulder, is supported by the Inorganic, Bioinorganic, and Organometallic Chemistry Program for investigation of C=O, C-S, and C-N bond cleavage reactions promoted by transition metal complexes containing sulfide ligands. In the case of C=O, for example, it is expected that carbon monoxide would insert into an SH bond of an SH ligand which serves as a bridge for a molybdenum dimer. The formylthiolate thus produced is susceptible to reductive cleavage of the C=O bond by hydrogen. This could model a first step of the conversion of CO to methane, a reaction not commonly promoted by transition metal complexes, and here promoted by bonding to sulfur rather than to the metal. This study might provide insight into the mechanism of CO reduction catalyzed by heterogeneous molybdenum sulfides. In studies of C-N bond cleavage by hydrogen, the sulfided metal complexes would serve as models of the heterogeneous catalysts used in commercial HDN (hydrodenitrogenation) processes. In addition to the reactions described above, novel complexes containing Ir, Rh, Re, Mo, and Mo-Cr and a variety of sulfur- and nitrogen-containing ligands will be prepared. %%% This project is expected to provide insight into the reactions of transition metal complexes with small molecules, which are important in the use of such complexes as heterogeneous and homogeneous catalysts. Specifically, these studies may provide information pertinent to understanding the behavior of commercial heterogeneous catalysts used for hydrodenitrogenation.