Cyclometalated phosphinine-iridium(III) complexes: synthesis, reactivity, and application as phosphorus-containing water-oxidation catalysts

The novel phosphinine-based coordination compound [Cp∗Ir(P^C)(CH₃CN)]CF₃SO₃ (P^C = cyclometalated 2,4,6-triphenylphosphinine) could be synthesized by chloride abstraction from [Cp∗Ir(P^C)Cl] with AgOSO₂CF₃ and crystallographically characterized. It turned out that this species is the first phosphorus-containing Ir(III) complex which shows a remarkable activity in the cerium ammonium nitrate driven water oxidation reaction. In situ NMR spectroscopic investigations further reveal that water is added selectively to one of the P=C double bonds with formation of four stereoisomers. Moreover, [Cp∗Ir(P^C)] species, possibly OH-functionalized but still having Cp∗ and P^C-ligands contemporary bound to iridium, are present in solution, even under catalytic conditions. (Figure Presented).