Articles written in Journal of Chemical Sciences
Volume 119 Issue 1 January 2007 pp 3-9
Reactions of IrCl3$\cdot$ 𝑥 H2O with the ligands, 2-[(phenylamino)phenylazo]pyridine (HL1a) and 2-[(𝑝-tolylamino)phenylazo]pyridine (HL1b) produce [Ir(L1)2]Cl (L1 = L1a, Cl and L1 = L1b, Cl) along with many unidentified products. The iridium complexes have been characterized by various techniques such as X-ray crystallography, mass spectrometry, 1H and 13C NMR, cyclic voltammetry and absorption studies. The complex ClO4 crystallises in triclinic space group. The crystallographic data have been determined. Notably, the Ir-N (azo) lengths are short (av. 1.9875(4) Å) as compared to the remaining four Ir-N lengths (av. 2.052(5) Å). There is significant degree of ligand backbone conjugation in the coordinated ligands, which result in shortening of the C-N lengths on the other side of the middle phenyl ring and also in lengthening of the diazo (N=N) lengths. The complexes display multiple low energy transitions ranging between 1010 and 450 nm. These are electro active and show three reversible redox responses in the potential range, +1.5 V to -1.5 V. The cathodic potential responses are ascribed as ligand reductions, while the redox process at the anodic potential occurs at a mixed metal-ligand (HOMO) orbital.