High-Affinity Proton Donors Promote Proton-Coupled Electron Transfer by Samarium Diiodide.

The relationship between proton-donor affinity for SmII ions and the reduction of two substrates (anthracene and benzyl chloride) was examined. A combination of spectroscopic, thermochemical, and kinetic studies show that only those proton donors that coordinate or chelate strongly to SmII promote anthracene reduction through a PCET process. These studies demonstrate that the combination of SmII ions and water does not provide a unique reagent system for formal hydrogen atom transfer to substrates. [ABSTRACT FROM AUTHOR]