The design and optimization of novel electrocatalysts requires robust structure-activity data to correlate catalyst structure with electrochemical behavior. Aryl iodides have been gaining attention as metal-free electrocatalysts but experimental data is available for only a limited set of structures. Here we report electrochemical data for a family of 70 aryl iodides. Half-peak potentials are utilized as proxies for reduction potentials and reveal that despite differences in electrochemical reversibility, the potential for one-electron oxidation of 4-substituted aryl iodides to the corresponding iodanyl radicals is well-correlated with standard Hammett parameters. Additional data is presented for 3- and 2-substituted aryl iodides, including structures with potentially chelating 2-substituents that are commonly encountered in hypervalent iodine reagents. Finally, potential decomposition processes relevant to the (in)stability of iodanyl radicals are presented. We anticipate the collected data will advance the design and application of aryl iodide electrocatalysis.

We demonstrate that sequential disproportionation reactions can enable selective aggregation of two- or four electron-holes at a hypervalent iodine center. Disproportionation of an anodically generated iodanyl radical affords an iodosylbenzene...

The interfacial electron transfer events that underpin electrochemistry effect one-electron oxidation or reduction of substrates. In contrast, selective bond-forming and -breaking in synthetic chemistry requires the choreographed management of two-electron steps. Thus, application of electrochemistry in synthesis requires strategies to aggregate multiple redox equivalents to engender multi-electron reactions. Here we demonstrate that sequential disproportionation reactions can enable selective aggregation of two- or four electron-holes at a hypervalent iodine center. Disproportionation of an anodically generated iodanyl radical (i.e., I(II) species) affords an iodosylbenzene derivative (i.e., I(III) species). Subsequent iodosylbenzene disproportionation can be triggered to provide access to iodoxybenzene (i.e., I(V) species). Both the transient iodanyl radical intermediate that engages in disproportionation to afford I(III) species and the O-bridged bis-I(III) compound that mediates iodosylbenzene disproportionation to afford I(V) species have been directly characterized. These results represent the first example of iodanyl radical disproportionation as a means to access I(III) compounds and demonstrate aggregation of four electron at the one-electron potential by selective and sequential disproportionation chemistry.