Scheme 16.

Illustration of several common catalyzed manifolds of electrochemical reactions using redox-innocent catalysts (A, B) and redox-active catalysts (C, D, E). (A) HOMO-activation of substrate by a catalyst (facilitates oxidation), (B) LUMO-activation of substrate by a catalyst (facilitates reduction), (C) catalyst only facilitates redox events (outer sphere electron transfer) (D) and (E) catalyst only facilitates redox event (either outer or inner-sphere electron transfer), (F) catalyst facilitates both redox and chemical events. [All redox events are shown as single electron events but redox events involving >one electron also fall into these categories].