Development of a Hydride Donor Scale

无机化学、生物无机化学和金属有机化学项目的这一奖项支持由科罗拉多大学博尔德分校化学和生物化学系的Mary Rakowski DuBois教授和科罗拉多州戈尔登国家可再生能源实验室的Daniel DuBois博士开发氢化物捐赠者标尺的研究。一系列现有的和新合成的等电子和等结构过渡金属氢化双膦配合物将被用来确定它们的氢化物给体强度，由异解键解离自由能来测量。酸度和均解键解离自由能也将作为热力学循环的一部分来确定，以获得与底物和溶剂无关的给体强度标度。在这个标度建立后，一些具有一定给体能力的化合物将与有机底物反应，以检查这些给体的值与氢化物反应性(“DONITY”)之间的关系。这一热力学标度将被扩展，以获得甲基正离子、阴离子和自由基转移的相对值。本研究的目标是开发金属氢化物向底物转移氢的能力的定量标度，并将这些数字与其反应活性联系起来。有机化合物的催化氢化反应具有重要的工业意义，金属氢化物往往是这些反应的中间体。这项研究的结果将为设计更有效的催化工艺提供支持，本工作制备的一些金属氢化物本身可能具有作为反应物或催化材料的价值。参与该项目的学生将学习合成和仪器方法方面的广泛技能，并在将基础化学与工业催化联系起来的努力中获得经验。

This award in the Inorganic, Bioinorganic and Organometallic Chemistry program supports research on the development of a hydride donor scale scale by Professor Mary Rakowski DuBois of the Department of Chemistry and Biochemistry at the University of Colorado-Boulder and Dr. Daniel DuBois at the National Renewable Energy Laboratory, Golden, Colorado. A series of both existing and newly-synthesized isoelectronic and isostructural transition metal hydridse diphosphine complexes will be employed to determine their hydride donor strength as measured by the heterolytic bond dissociation free energies. The acidities and homolytic bond dissociation free energies will also be determined as part of the thermodynamic cycles used to obtain this substrate and solvent-independent donor strength scale. After this scale is established, a number of compounds with a range of donor abilities will be reacted with organic substrates to examine the relationship between these donor values and hydride reactivity ("donicity"). This thermodynamic scale will be extended to obtain relative values for the transfer of the methyl cation, anion and radical.The goal of this research is to develop a quantitative scale for the ability of metal hydride compounds to transfer hydrogen to a substrate, and to relate these numbers to their reactivity. Catalytic hydogenation of organic compounds is of great industrial importance, and metal hydrides are often intermediates in these reactions. The results of this study will support the design of more efficient catalytic processes, and some of the metal hydrides prepared in this work may themselves have value as reactant or catalytic materials. Students involved in the project will learn a breadth of skills in both synthesis and instrumental methods, and gain experience in an effort which links fundamental chemistry with industrial catalysis.