Preparation, Characterization, and Electrochemical Activation of a Model [Cp*Rh] Hydride
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Issue Date
2018-09-26Author
Boyd, Emily A.
Lionetti, Davide
Henke, Wade C.
Day, Victor W.
Blakemore, James D.
Publisher
American Chemical Society
Type
Article
Article Version
Scholarly/refereed, author accepted manuscript
Rights
Copyright © 2018 American Chemical Society
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Monomeric half-sandwich rhodium hydride complexes are often proposed as intermediates in catalytic cycles, but relatively few such compounds have been isolated and studied, limiting understanding of their properties. Here, we report preparation and isolation of a monomeric rhodium(III) hydride complex bearing the pentamethylcyclopentadienyl (Cp*) and bis(diphenylphosphino)benzene (dppb) ligands. The hydride complex is formed rapidly upon addition of weak acid to a reduced precursor complex, Cp*Rh(dppb). Single-crystal X-ray diffraction data for the [Cp*Rh] hydride, which were previously unavailable for this class of compounds, provide evidence of the direct Rh–H interaction. Complementary infrared spectra show the Rh–H stretching frequency at 1986 cm−1. In contrast to results with other [Cp*Rh] complexes bearing diimine ligands, treatment of the isolated hydride with strong acid does not result in H2 evolution. Electrochemical studies reveal that the hydride complex can be reduced only at very negative potentials (ca. −2.5 V vs. ferrocenium/ferrocene), resulting in Rh–H bond cleavage and H2 generation. These results are discussed in the context of catalytic H2 generation, and development of design rules for improved catalysts bearing the [Cp*] ligand.
Description
This document is the Accepted Manuscript version of a Published Work that appeared in final form in Inorganic Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.inorgchem.8b02160.
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Citation
Boyd, E. A., Lionetti, D., Henke, W. C., Day, V. W., & Blakemore, J. D. (2019). Preparation, Characterization, and Electrochemical Activation of a Model [Cp*Rh] Hydride. Inorganic chemistry, 58(6), 3606–3615. https://doi.org/10.1021/acs.inorgchem.8b02160
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