The study of electron transfer (ET) across non-covalent interactions remains an understudied, yet rapidly growing field within the scientific community. In many biological and artificial systems electron transport is carried out by shuttling electrons through multiple redox sites within the structure. Many enzymes use proton coupled electron transfer as a means to move electrons, and while very few examples exist, hydrogen bonded mixed valent compounds offer considerable insight into this mechanism. In the last several years we have synthesized a series of oxocentered triruthenium clusters of the type [Ru3(μ3-O)(Ac)6(CO)(X)(INA)] where X = 4-cyanopyridine, pyridine, or 4-dimethylaminopyridine and INA = isonicotinic acid. By using the isonicotinic acid fragment, we have been able to form simple hydrogen bonded mixed valence dimers to investigate long range ET mechanisms. In these systems we have found that the mixing of the metal center and ligand wave functions allows for an indirect mechanism for donor- acceptor overlap to occur. This leads to the observation of significant electronic coupling in a system that would otherwise be considered too far apart or too weakly coupled to give rise to a stable mixed-valence state (Kce(nFE1/2)/(RT) ≈ 105). Furthermore, through the use of 1H NMR, we have been able to show that the formation of this mixed valent state strengthens the hydrogen bonding interaction found in such systems.

Measurement of electron delocalization energy in hydrogen-bonded mixed valent Ru3O acetate clusters

251st National Meeting (2016)

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