Is the 3MLCT the only photoreactive state of polypyridyl complexes?

Inorg Chem. 2007 Apr 16;46(8):3154-65. doi: 10.1021/ic062193i. Epub 2007 Mar 21.

Abstract

By means of Delta-SCF and time-dependent density functional theory (DFT) calculations on [Ru(LL)3]2+ (LL = bpy = 2,2'-bipyridyl or bpz = 2,2' -bipyrazyl) complexes, we have found that emission of these two complexes could originate from two metal-to-ligand charge-transfer triplet states (3MLCT) that are quasi-degenerate and whose symmetries are D3 and C2. These two states are true minima. Calculated absorption and emission energies are in good agreement with experiment; the largest error is 0.14 eV, which is about the expected accuracy of the DFT calculations. For the first time, an optimized geometry for the metal-centered (MC) state is proposed for both of these complexes, and their energies are found to be almost degenerate with their corresponding 3MLCT states. These [RuII(LL)(eta1-LL)2]2+ MC states have two vacant coordination sites on the metal, so they may react readily with their environment. If these MC states are able to de-excite by luminescence, the associated transition (ca. 1 eV) is found to be quite different from those of the 3MLCT states (ca. 2 eV).

MeSH terms

  • Ligands
  • Models, Chemical*
  • Models, Molecular
  • Molecular Structure
  • Organometallic Compounds / chemistry*
  • Photochemistry
  • Pyridines / chemistry*
  • Quantum Theory
  • Ruthenium / chemistry*

Substances

  • Ligands
  • Organometallic Compounds
  • Pyridines
  • Ruthenium