Synthesis, x-ray structure, electrochemical and electronic properties of [3-(pyridin-2-yl)-4-methyl-1,2,4-triazole-bis(2-(2′-phenylato)pyridine)-iridium(III)] hexafluorophosphate

Abstract

A new orthometalated iridium(III) complex [Ir(ppy) 2(4mptr)](PF 6) with ppy= 2-(2′-phenylato)pyridine and 4mptr=4-methyl-3-(pyridin-2-yl)-l,2,4-triazole has been synthesised and characterised by X-ray structure analysis, NMR spectroscopy, electrochemical measurements, UV-Vis absorption, and emission spectroscopy. The compound crystallises in the orthorhombic space group Pbca, with a = 10.906(4), b = 16.139(6), c =32.876(12) Å and Z= 8. The cation has a distorted octahedral IrN 4C 2 chromophore, with two chelating (C,N) ppy ligands ((IrC)=2.01 Å, (IrN)=2.05 Å). The two carbon atoms are cis and the two nitrogen atoms trans to each other. The 4mptr ligand chelates via the pyridine nitrogen (IrN13=2.18 Å) and N2 of the triazole ring (IrN2=2.14 Å), both trans to a carbon atom. The complex is reversibly reduced in CH 3CN at −1.57 V (SCE) and irreversibly oxidised at + 1.20 V (SCE). The lowest UV-Vis absorption band at 380 nm (ϵ=5400) has been assigned to a d →-π * (ppy) MLCT transition. A highly-structured emission band (471/505 nm) is observed at 77 K, while at room temperature, only a broad emission (582 nm) is present.