Microwave Measurements of Structures and Electronic Properties of Transition Metal Complexes, Hydrogen-Bonded Complexes, and Radicals

获得化学结构、动力学和机制项目的这一奖项后，亚利桑那大学的Stephen Kukolich教授将修改并使用脉冲光束傅立叶变换微波光谱仪来测量微波光谱1至18 GHz区域的旋转跃迁频率。新完成的1-10 GHz光谱仪提供了一种不同寻常的能力，可以测量较大分子和复合物的低频跃迁。激光光解光束源将用于测量有机金属自由基及其反应产物。这项工作的总体目标包括测量三维气相结构、四极耦合强度和磁相互作用参数。这些测量建议：a)单核和双核过渡金属配合物，b)涉及过渡金属的弱结合配合物，c)氢键配合物和d)过渡金属自由基。四极耦合强度和磁相互作用参数直接表征了电子电荷分布。量子力学（DFT或mp2）计算将对所有研究的复合物进行。实验工作与理论计算的协调有助于提高测量效率，提高我们对分子电子结构的理解，并为从头算、量子化学计算的改进提供指导和实验实例。过渡金属配合物在化学工业、生物系统和无机化学研究中都具有重要的意义。每年有数百万吨的化学产品是通过涉及过渡金属催化剂的反应生产出来的。生命系统中许多酶和转运蛋白的活性位点都含有过渡金属配合物。无机化学的大部分研究都集中在过渡金属配合物上，所提出的工作将为研究、工业和教育中使用的结构数据库提供新的贡献。建议的工作通常涉及较小的“模型”复合体，但将提供与较大的、更复杂的系统相关的结果。过渡金属配合物精确的三维结构有助于理解反应机理。化学和生物学中反应机理的成功建模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集是有用的，因为计算是目前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。金属二氢配合物的研究可以为改进储氢技术提供有用的信息。研究生和本科生将学习化学基础知识、量子力学、计算机工作方法和技术、微波电子学以及通过直接参与拟议项目进行物理测量。少数族裔、中学教师或非博士参与研究。将积极寻求大学生参与拟议的项目。

With this award from the Chemical Structure, Dynamics and Mechanisms program, Professor Stephen Kukolich of the University of Arizona will modify and use pulsed-beam, Fourier-transform microwave spectrometers to measure rotational transition frequencies in the 1 to 18 GHz region of the microwave spectrum. The completion of a new 1-10 GHz, spectrometer provides an unusual capability for measuring lower frequency transitions of larger molecules and complexes. A laser-photodissociation beam source will be used for measurements on organometallic radicals and their reaction products. The overall objectives of this work include measurements of the three-dimensional gas-phase structures, quadrupole coupling strengths and magnetic interaction parameters. These measurements are proposed for: a) mononuclear and dinuclear transition metal complexes, b) weakly-bound complexes involving transition metals, c) hydrogen-bonded complexes and d) transition metal radicals. The quadrupole coupling strengths and magnetic interaction parameters directly characterize the electronic charge distributions. Quantum mechanical (DFT or mp2) 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 secondary school teachers, or non-Ph.D. college students will be actively sought for the proposed projects.