Microwave Measurements of Structures and Electronic Properties of Transition Metal Complexes and Radicals

获得实验物理化学项目的这一奖项后，亚利桑那大学的P.I.史蒂芬·库科利奇教授将改装和使用脉冲光束傅里叶变换微波光谱仪，测量过渡金属络合物、自由基和其他分子在微波光谱5至18 GHz区域的旋转跃迁频率。为测量有机金属自由基及其反应产物，将建立一种新的激光-光解离光束源。这将允许比大多数以前的系统更有效和更有选择性地生产这些自由基和反应产物。这项工作的总体目标包括测量三维气相结构、磁相互作用参数和四极耦合强度。这些测量适用于：a)过渡金属自由基和涉及这些自由基的反应产物，b)过渡金属二氢和二氢络合物，以及c)与过渡金属化合物的弱结合络合物。磁相互作用参数和四极耦合强度直接表征了电子电荷分布。对所研究的所有络合物进行量子力学(密度泛函理论)计算。实验工作与理论计算的结合有助于提高测量的效率，提高我们对分子电子结构的理解，并为从头计算、量子化学计算的改进提供指导和实验范例。过渡金属络合物在化学工业、生物体系和无机化学研究领域都是非常重要的。每年使用过渡金属催化剂的反应生产数百万吨的化学产品。生命系统中许多酶和转运蛋白的活性部位都含有过渡金属络合物。无机化学的研究和学习的很大一部分集中在过渡金属配合物上，拟议的工作将为用于研究、工业和教育的结构数据库提供新的贡献。拟议的工作通常涉及较小的？模型？但将提供与更大、更复杂的系统相关的结果。准确的过渡金属络合物的三维结构有助于理解反应机理。化学和生物反应机理的成功模拟往往依赖于准确可靠的实验结构信息。通过与新的实验数据相关联来改进计算方法和基组是有用的，因为这些计算目前是关于短寿命自由基或高能反应中间体的详细信息的唯一来源。金属二氢络合物的研究可能会为改进储氢技术提供有用的信息。研究生和本科生将通过直接参与拟议的项目，学习化学、量子力学的基础知识，以及计算机工作、微波电子学和物理测量方面的方法和技术。对于拟议的项目，将积极寻求代表人数不足的少数民族和一名中学教师或非博士生参与这项研究。

With this award from the Experimental Physical Chemistry program, the P.I., Professor Stephen Kukolich of the University of Arizona will modify and use a pulsed-beam, Fourier-transform microwave spectrometer to measure rotational transition frequencies for transition metal complexes, radicals, and other molecules in the 5 to 18 GHz region of the microwave spectrum. A new laser-photodissociation beam source will be constructed for measurements on organometallic radicals and their reaction products. This will allow more efficient and selective production of these radicals and reaction products, than most previous systems. The overall objectives of this work include measurements of the three-dimensional gas-phase structures, magnetic interaction parameters and quadrupole coupling strengths. These measurements are proposed for: a) transition metal radicals and reaction products involving these radicals, b) transition metal dihydrogen and dihydride complexes, and c) weakly-bound complexes with transition metal compounds. The magnetic interaction parameters and quadrupole coupling strengths directly characterize the electronic charge distributions. Quantum mechanical (Density Functional Theory) calculations will be carried out for all of the complexes studied. The coordination of experimental work with the theoretical calculations helps to make the measurements more efficient, improves our understanding of the electronic structure of molecules and provides guidelines and experimental examples for improvements in ab initio, quantum chemistry calculations. Transition metal complexes are very important in the chemical industry, in biological systems and as an area of study in inorganic chemistry. Millions of tons of chemical products are produced each year using reactions which involve transition metal catalysts. The active sites of many enzymes and transport proteins in living systems contain transition metal complexes. A large fraction of the research and study in inorganic chemistry is focused on transition metal complexes, and the proposed work will provide new contributions to the structural database that is used in research, industry and education. The proposed work will often involve smaller, ?model? complexes, but will provide results relevant to the larger, more complex systems. The accurate, three-dimensional structures for transition metal complexes, are helpful in understanding reaction mechanisms. Successful modeling of reaction mechanisms in chemistry and biology often depends on the accurate and reliable experimental structural information. Improving calculation methods and basis sets through correlation with new experimental data is useful because the calculations are presently the only source of detailed information on short-lived radicals or high-energy reaction intermediates. Studies of metal dihydrogen complexes may provide information which will be useful for improving hydrogen storage technology. Graduate and undergraduate research students will learn fundamentals of chemistry, quantum mechanics and methods and techniques involved in computer work, microwave electronics and making physical measurements through direct involvement in the proposed projects. Participation in the research by underrepresented minorities and a secondary school teacher, or non-Ph.D. college student will be actively sought for the proposed projects.