Half-sandwich rhodium hydrides are often proposed as intermediates in catalytic processes, but only limited examples of such compounds are available. We have recently been exploring the chemistry of a family of Cp*Rh(dppf) rhodium complexes supported by the η5-pentamethylcyclopentadienyl (Cp*) and κ2-bis-diphenylphosphinoferrocene (dppf) ligands to provide new insights into the reactivity patterns of such compounds. We find that protonation of Cp*Rh(dppf) with DMFH+OTf– yields an isolable monohydride, but that further protonation to generate dihydrogen does not occur even with strong acids. Unlike most [Cp*Rh] complexes which display net two-electron RhIII/I redox cycling, Cp*Rh(dppf) displays well-resolved one-electron redox, including a unique quasi-reversible one-electron RhII/I process at –0.96 V vs. ferrocenium/ferrocene (Fc+/0). Chemical preparation of the relatively uncommon rhodium(II) species enabled its characterized with electron paramagnetic resonance (EPR). In this poster, the synthesis and redox properties of this family of complexes will be discussed, including spectroscopic studies aimed at identifying the multiple accessible oxidation states.

Chemical and electrochemical properties of [Cp*Rh] complexes supported by a redox-active ligand

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.