Kinetics and Mechanisms of Organometallic Reactions

这个无机、生物无机和有机金属项目的奖项将继续支持伊利诺伊大学厄巴纳-香槟分校化学系的Theodore L. Brown博士对过渡金属有机金属化合物在溶液中的反应机制的研究。将进行三项主要调查。首先，选定化合物的羰基配体的损失将被光化学促进，并使用低温红外光谱研究反应中间体。用这种方法研究双核金属羰基、铬羰基配合物、氢锡化和氢硅化反应。其次，基于马库斯理论的假设，建立有机金属反应的线性自由能关系。这部分研究的目的是提高预测由于反应条件的改变而导致的反应速率变化的能力。特别是，随着配体的变化，电子或空间因子变化的后果将被研究，特别是在原子转移和结合取代反应中。第三，分子力学将用于评价配体的空间效应。早期的结果表明，用这种方法可以成功地解释配体锥角的影响。对有机金属化合物的反应机理的研究已经达到了一个结果可以开始系统化和普遍化的阶段。这项工作将为预测一些涉及羰基配体损失、原子转移和配体交换的反应的反应性提供指导。将特别注意评估配体对反应性的影响。这些研究对有机金属化学和涉及有机金属化合物的催化过程的基本认识具有重要意义，并可能对催化剂的设计有帮助。

This award in the Inorganic, Bioinorganic, and Organometallic Program will provide continued support to Dr. Theodore L. Brown of the Chemistry Department, University of Illinois at Urbana-Champaign, for the study of reaction mechanisms of transition metal organometallic compounds in solution. Three main lines of investigation will be pursued. First, the loss of carbonyl ligands from selected compounds will be promoted photochemically, and the reaction intermediates studied using low temperature infrared spectroscopy. Dinuclear metal carbonyls, chromium carbene complexes, hydrostannation and hydrosilation will be studied using this method. Secondly, linear free energy reationships for organometallic reactions will be developed, based on the assumptions of Marcus theory. The purpose of this portion of the reseach is to enhance the ability to predict changes in reaction rates that result from modification of reaction conditions. In particular, the consequences of changes in electronic or steric factors as ligands are varied will be investigated, especially in atom transfer and associative substitution reactions. Thirdly, molecular mechanics will be used to evaluate ligand steric effects. Early results indicate that the influence of ligand cone angles can be successfully interpreted using this approach. %%% Investigation of reaction mechanisms of organometallic compounds is reaching a stage in which the results can begin to be systematized and generalized. This work will provide guidelines for predicting reactivity in some reactions involving loss of a carbonyl ligand, atom transfer, and ligand exchange. Particular attention will be paid to assessing the effect of ligands on reactivity. These studies are important for the fundamental understanding of organometallic chemistry and catalytic processes involving organometallic compounds, and could be helpful for catalyst design.