Formation of N-oxide in the third oxidation of [RuII(tpy)(L)(OH2)]2+

Abstract

The widely studied water oxidation catalyst [Ru^II(tpy)(L)(OH₂)]²⁺ (tpy = 2,2′:6′,2′′-terpyridine, L = bpy = 2,2′-bipyridine or L = bpm = 2,2′-bipyrimidine) is still under scrutiny. Here we present a new suggestion for one of the key steps, results that could resolve conflicting interpretations of experimental results. Instead of the previously proposed Ru^VO species, a proposed key species in water oxidation catalysis, we propose that the third oxidation of Ru^II could lead to a Ru^IIIN-oxide, via rapid water coordination followed by oxidation and concerted N–O bond formation.