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Keywords:

  • Ir(ppy)3;
  • [Ir(ppy)2bpy]+;
  • SERS

Abstract

The Raman and infrared spectra of fac-tris(2-phenylpyridinato-N,C2′)iridium(III), Ir(ppy)3 and surface-enhanced resonance Raman spectra of bis(2-phenyl pyridinato-) (2,2′bipyridine) iridium (III), [Ir(ppy)2 (bpy)]+ cation were recorded in the wavenumber range 150–1700 cm−1, and complete vibrational analyses of Ir(ppy)3 and [Ir(ppy)2 (bpy)]+ were performed. Most of the vibrational wavenumbers were calculated with density-functional theory agree with experimental data. On the basis of the results of calculation and comparison of the spectra of both complexes and their analogue [Ru(bpy)3]2+, we assign the vibrational wavenumbers for metal–ligand modes; metal–ligand stretching wavenumbers are 277/307 and 261/236 cm−1 for Ir(ppy)3, and 311/324, 257/270, 199/245 cm−1 for [Ir(ppy)2 bpy]+. Surface-enhanced Raman scattering spectra of [Ir(ppy)2 bpy]2+ were measured at two wavelengths on the red and blue edges of the low-energy metal-to-ligand charge-transfer band. According to the enhanced Raman intensities for the vibrational modes of both ligands ppy and bpy, the unresolved charge-transfer band is deduced to consist of charge-transfer transitions from the triplet metal to both ligands ppy and bpy. Copyright © 2010 John Wiley & Sons, Ltd.