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，研究无机和有机金属系统中的电荷转移。这些研究包括通过电子交换在各种三钌簇化合物中动态平均红外光谱的实验表征。这类三核分子离子中钌中心之间电子相互作用的差异解释了振动时间尺度上下的电子转移速率。系统研究可调参数（配体，溶剂等）变化的影响，用于测试电子转移理论（例如，Marcus-Hush）在弱局域和完全离域行为之间的阈值。其他相关的研究将涉及聚硅烷和多铬化合物。电子转移反应在化学和相关科学领域的许多不同领域都具有核心重要性，包括多种类型的生物电荷转移。由于电子相对于原子核来说是非常轻的，所以可以从理论上详细地讨论电子转移反应，这对于大多数其他种类的化学变化是不可能的。强大的理论（如Marcus -Hush）可以成功地处理电子供体和电子受体中心只有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，已被证明更难以理解。PI和他的团队已经证明，三核钌配合物的振动（IR）光谱的精细细节对影响这些配合物中电子转移速率的可调参数的看似微小的变化很敏感。本项目利用红外光谱的这些变化来探测这些物种的分子内耦合，并测试和扩展具有中间供体-受体相互作用的系统的电子转移理论。这是一个非常重要的参数空间区域，但以前很少被理解。

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.