Syntheses, crystal structures and phosphorescence properties of cyclometalated iridium(III) bis(pyridylbenzaldehyde) complexes with dithiolate ligands

The synthesis of three neutral bis-cyclometalated iridium(III) complexes [Ir(pba)(2)(S<^>S)] (pbaH = 4-(2-pyridyl) benzaldehyde; S<^>S = Et-2 NCS2- (1), (PrOCS2-)-Pr-i (2), ((PrO)-Pr-n)(2)PS2- (3)) from [{Ir(mu-Cl)(pba)(2)}(2)] and the corresponding sodium or potassium dithiolates in methanol-dichloromethane is described. The composition of complexes 1-3 is discussed on the basis of H-1 NMR, C-13 NMR, IR, and mass spectroscopy, and the crystal structures of 1 and 3 were determined by X-ray crystallography. The absorption and emission spectra show that the [Ir(pba)(2)(S<^>S)] complexes may be effective candidates as green-emitting phosphorescent materials. The stability of the three cyclometalated iridium(III) complexes towards different transition metal ions was also investigated in acetonitrile-water solvent.