Patterns in Sigma Bond Complexation

该项目由无机、生物无机和有机金属化学项目资助，主要研究X-H键（X=H、N、Si及其同系物和M）与过渡金属的配位化学的进一步发展。这是最近公认的有机金属化学领域，其基本原理尚不清楚；本研究的目的是发现跨越几类sigma键配合物的一般趋势。要追求的几个目标是：通过空间拥挤产生“拉伸”二氢配合物和新的多氢物种，证明不对称桥接金属氢化物的反应性变化，以及证明sigma键结合的N-H配合物的独特反应性。将寻求基于核磁共振光谱的检测和表征这类化合物的技术。最近过渡金属化学中最令人兴奋的发展之一是发现氢分子可以与金属配合物结合而不破坏氢键。克拉布特里教授在阐明决定氢分子如何与金属结合的因素和发展确定结合模式的光谱技术方面发挥了重要作用。本项目试图确定这种sigma键配合物在其他X-H键的过渡金属化学中所起的作用。最终，从这项工作中获得的信息将对更好地理解有机金属反应机制的发展具有重要意义，并可能有助于为工业上重要的反应设计更具体的催化剂。＊＊＊

9401739 Crabtree This project, supported by the Inorganic, Bioinorganic and Organometallic Chemistry Program, is concerned with the further development of the chemistry of X-H sigma-bonds (X=H, N, Si and its congeners, and M) coordinated to transition metals. This is a recently recognized area of organometallic chemistry for which the underlying principles are unclear; the goal of this reseach is to discover general trends across several classes of sigma-bond complexes. Among the several goals to be pursued are: generation of "stretched" dihydrogen complexes and new polyhydrogen species by steric crowding, demonstration of a change in reactivity for unsymmetrically bridged metal hydrides, and demonstration of a distinctive reactivity for sigma-bond bound N-H complexes. Techniques for detection and characterization of such compounds based upon NMR spectroscopy will be sought. %%% One of the most exciting recent developments in transition metal chemistry was the discovery that molecular hydrogen can bind to a metal complex without cleavage of the hydrogen-hydrogen bond. Professor Crabtree has played an important role in the elucidation of the factors that determine how molecular hydrogen will bind to a metal and in the development of spectroscopic techniques for determining the mode of binding. This project attempts to determine the role that such sigma-bond complexes play in transition metal chemistry of other X-H bonds. Ultimately the information obtained from this work will be important in the development of a better understanding of organometallic reaction mechanisms and may be useful in the design of more specific catalysts for industrially important reactions. ***