Electrochemistry of iridium tris- and bisesquis(phenanthroline) complexes

Abstract

Publication costs assisted by North Carolina State University Cyclic voltammetry data have been obtained for the trisand bisesquis(l,10-phenanthroline) (phen) complexes of iridium(III) in acetonitrile. A reaction mechanism is proposed on the basis of the analysis of electrochemical and luminescence data. For the bisesqui-and tris(phen) complexes the mechanisms are similar to the corresponding 2,2'-bipyridine (bpy) Ir(III) complexes except that an insoluble deposit forms after three electrons have been transferred. Similar behavior has been observed for the reduction of [Ru(bpy)3]2+, however, comparison of the reverse (oxidation) scan for the first reduction wave of the tris Ir(III) and Ru(II) complexes indicates distinctly different behavior. These data are interpreted as resulting from the multiring delocalized redox orbital of the Ru(II) complex and the single ring delocalized redox orbital of the Ir(III) complex.

“Rollover” cyclometalation – early history, recent developments, mechanistic insights and application aspects

“…2a): i) complex 4, in which water is directly bound to the iridium center, while one bipy ligand coordinates in a monodentate fashion and ii) structure 5 in which one bipy ligand is ''covalently hydrated'', thus also acting as a monodentate ligand. 32,88 Despite the controversies about the structural assignment of the third bipy ligand in the ''Watts complex'', [89][90][91][92][93] the correct structure remained shrouded in mystery Fig. 1 Classical cyclometalation (1 / 2) versus ''rollover'' cyclometalation (1 / 3) for a metal complex containing 6-phenyl-2,2 0bipyridine as a ligand.…”