Cyclometalated Iridium Bipyridine Complexes with Peripheral Antimony Substituents

Abstract

As part of our ongoing efforts in the development of main group Lewis acids as anion receptors, we have investigated the synthesis of cyclometalated bipyridine iridium(III) complex decorated by antimony moieties. Reaction of 4‐(diphenylstibino)‐2,2'‐bipyridine (L) with [(ppy)2Ir(μ‐Cl)]2 afforded the corresponding tris‐chelate iridium complex [(ppy)2IrL]+ ([1]+), which was isolated as a hexafluorophosphate salt ([1][PF6]). Reaction of [1][PF6] with excess PhICl2 in DMSO induced the conversion of the diphenylantimony moiety of [1]+ into an anionic diphenyltrichloroantimonate leading to a zwitterionic complex referred to as 2‐Cl. Complexes [1][PF6] and 2‐Cl were characterized by NMR and the structure of 2‐Cl confirmed using X‐ray diffraction. DFT calculations and electrochemical measurments show that the electron‐rich diphenyltrichloroantimonate moiety in 2‐Cl cathodically shifts the Ir(III/IV) redox couple. Luminescence measurements also show that 2‐Cl is less emissive than [1]+.