Synthesis, Structure, and Electronic Properties of Late First-Row Transition Metal Complexes of Fluorinated Alkoxides and Aryloxides

Abstract The synthesis, structure, and electronic properties of several series of late first-row transition metal complexes stabilized by highly-fluorinated alkoxide and aryloxide (ORF) ligands, including partially fluorinated OAr’ (3,5-OC6H3(CF3)2)− and fully fluorinated OArF (OC6F5)−, perfluoro-tbutoxide (OC4F9)−, and perfluoropinacolate, denoted as pinF, (O({C(CF3)2}2)2− are described herein. Compared to their protio counterparts, the powerful electron-withdrawing nature of these fluorinated ligands makes them considerably less basic and some syntheses may be conveniently carried out in aqueous media when the metal redox chemistry is compliant. Additionally, the decreased propensity of these ligands to form bridging complexes reduces the number of dimeric or polymeric extended structures, leading to monomeric systems whose corresponding protio analogs may not be synthetically achieved. As pseudo-halogens, these ligands have been found to be electronically similar to fluoride (F−), and in several cases, spectroscopic characterization of their corresponding metal complexes has revealed high-spin electronic configurations, justifying their description as medium field ligands. Furthermore, interactions between and O/F atoms on the ligand and counter-cations such as K+ and Tl+ play a key structural role, influencing the solubility and solid-state nuclearity or geometry of the complexes.