Iridium mediated phenolic O-H activation and cyclometalation of 2-(naphthyl-1'-azo)-4-methylphenol - Formation of organoiridium complexes
Journal
Journal of Chemical Sciences
Journal Volume
121
Journal Issue
4
Pages
387-395
Date Issued
2009
Author(s)
Abstract
Reaction of 2-(naphthyl-1'-azo)-4-methylphenol with [Ir(PPh 3)3Cl] in refluxing ethanol in the presence of a base (NEt3) affords an organoiridium complex of type [Ir(PPh 3)2(L)(H)], where L represents the coordinated 2-(naphthyl-1'-azo)-4-methylphenolate ligand. A similar reaction carried out in toluene affords the [Ir(PPh3)2(L)(H)] complex along with a similar complex of type [Ir(PPh3)2(L)Cl]. Structures of both the [Ir(PPh3)2(L)(H)] and [Ir(PPh3) 2(L)Cl] complexes have been determined by X-ray crystallography. In both the complexes, 2-(naphthyl-1'-azo)-4-methylphenol is coordinated to iridium, via C-H activation at the 2' position of the naphthyl ring, as a dianionic tridentate C,N,O-donor and the two triphenylphosphines are trans. The organoiridium complexes show intense MLCT transitions in the visible region. Cyclic voltammetry on the [Ir(PPh3)2(L)(H)] and [Ir(PPh3)2(L)Cl] complexes shows a reversible Ir(III)-Ir(IV) oxidation respectively at 0.55 and 0.73 V vs SCE. An irreversible oxidation of the coordinated 2-(naphthyl-1'-azo)-4-methylphenolate ligand is observed above 1.0 V vs SCE and an irreversible reduction of the same is observed near -1.0 V vs SCE. © Indian Academy of Sciences.
SDGs
Type
journal article