Inorganic and Organometallic Charge Transfer

加州大学圣地亚哥分校的Clifford P.Kubiac得到了无机、生物无机和有机金属化学项目的支持，该项目旨在研究无机和有机金属体系中的电荷转移。这些研究涉及各种三Ru簇合物中通过电子交换动态平均红外光谱的实验表征。这种三核分子离子中的Ru中心之间的电子相互作用的差异解释了电子转移的速度在振动时间标度之上和之下的范围。对可调参数(配体、溶剂等)变化的影响进行了系统研究用于在弱局域行为和完全离域行为之间的阈值处测试电子转移理论(例如，Marcus-Hush)。其他相关的研究将涉及聚硅烷和多铬化合物。电子转移反应在许多不同的化学领域和相关的科学领域中具有核心重要性，包括许多类型的生物电荷转移。由于电子相对于原子核是非常轻的，所以电子转移反应可以在理论上详细地讨论，这对于大多数其他类型的化学变化是不可能的。强大的理论(例如Marcus-Hush)可以成功地处理电子给体和电子受体中心只是弱耦合的电荷转移反应-或者当这两个中心强烈混合时。在中间情况下，供体和受体中心之间的相互作用既不是很强也不是很弱，事实证明更难理解。Pi和他的团队已经证明，三核Ru络合物的振动(IR)光谱的精细细节对影响这些络合物中电子转移速率的可调参数的微小变化很敏感。这个项目利用红外光谱中的这些变化来探测这些物种中的分子内耦合，并测试和扩展具有中间供体-受体相互作用的体系的电子转移理论。这是参数空间的一个基本的重要区域，但以前人们对它知之甚少。

Clifford P. Kubiac of the University of California, San Diego is supported by the Inorganic, Bioinorganic, and Organometallic Chemistry program for research on charge transfer in inorganic and organometallic systems. These studies involve experimental characterization of dynamical averaging of infra-red spectra by electron exchange in a variety of triruthenium cluster-compounds. Differences in electronic interactions among the ruthenium centers in such trinuclear molecular ions account for rates of electron transfer that range both above and below the vibrational time scale. Systematic study of the effects of variation in adjustable parameters (ligands, solvent, etc.) are used to test theories of electron transfer (e.g., Marcus-Hush) at the threshold between weakly-localized and fully-delocalized behavior. Other, related, studies will involve polysilanes and polychromium compounds.Electron-transfer reactions are of central importance in many diverse areas of chemistry and related scientific areas, including biological charge transfers of many types. Since the electron is very light with respect to atomic nuclei, electron-transfer reactions can be discussed theoretically in a level of detail that is impossible for most other kinds of chemical change. Powerful theories (e.g. Marcus -Hush) can deal successfully with charge-transfer reactions in which the electron-donor and electron-acceptor centers are only weakly coupled --- or when these two centers are strongly mixed. The intermediate case, in which interaction between donor and acceptor centers are neither very strong or very weak, has proved more difficult to understand. The PI and his group have shown that the fine details of the vibrational (IR) spectra of trinuclear ruthenium complexes are sensitive to seemingly small changes in adjustable parameters that influence the rate of electron transfer in those complexes. This project uses these changes in IR spectra to probe intra-molecular coupling in these species, and to test and extend theories of electron-transfer for systems with intermediate donor-acceptor interaction. This is a fundamentally important, but previously poorly-understood, region of parameter-space.