Deaton, Joseph C. and Taliaferro, Chelsea M. and Pitman, Catherine L. and Czerwieniec, Rafal and Jakubikova, Elena and Miller, Alexander J. M. and Castellano, Felix N. (2018) Excited-State Switching between Ligand-Centered and Charge Transfer Modulated by Metal-Carbon Bonds in Cyclopentadienyl Iridium Complexes. INORGANIC CHEMISTRY, 57 (24). pp. 15445-15461. ISSN 0020-1669, 1520-510X
Full text not available from this repository. (Request a copy)Abstract
Three series of pentamethylcyclopentadienyl (Cp*) Ir(III) complexes with different bidentate ligands were synthesized and structurally characterized, [Cp*Ir(tpy)L](n+) (tpy = 2-tolylpyridinato; n = 0 or 1), [Cp*Ir(piq)L](n+) (piq = 1-phenylisoquinolinato; n = 0 or 1), and [Cp*Ir(bpy)L](m+) (bpy = 2,2'-bipyridine; m = 1 or 2), featuring a range of monodentate carbon -donor ligands within each series [L = 2,6-dimethylphe-nylisocyanide; 3,5-dimethylimidazol-2-ylidene (NHC); methyl)]. The spectroscopic and photophysical properties of these molecules and those of the photocatalyst [Cp*Ir(bpy)H](+) were examined to establish electronic structure-photophysical property relationships that engender productive photochemical reactivity of this hydride and its methyl analogue. The Ir(III) chromophores containing ancillary CNAr ligands exhibited features anticipated for predominantly ligand-centered (LC) excited states, and analogues bearing the NHC ancillary exhibited properties consistent with LC excited states containing a small admixture of metal-to-ligand charge-transfer (MLCT) character. However, the molecules featuring anionic and strongly sigma-donating methyl or hydride ligands exhibited photophysical properties consistent with a high degree of CT character. Density functional theory calculations suggest that the lowest energy triplet states in these complexes are composed of a mixture of MLCT and ligand-to-ligand CT originating from both the Cps* and methyl or hydride ancillary ligands. The high degree of CT character in the triplet excited states of methyliridium complexes bearing C<^>N-cyclometalated ligands offer a striking contrast to the photophysical properties of pseudo-octahedral structures fac-Ir(C<^>N)(3) or Ir(C<^>N)(2)(acac) that have lowest-energy triplet excited states characterized as primarily LC character with a more moderate MLCT admixture.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | CYCLOMETALATED IR(III) COMPLEXES; GAS SHIFT REACTION; MOLECULAR-ORBITAL METHODS; PHOTOPHYSICAL PROPERTIES; TEMPERATURE-DEPENDENCE; RUTHENIUM(II) COMPLEXES; MILD CONDITIONS; DECAY DYNAMICS; TRIPLET-STATE; BLUE; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Research Group Theoretical Chemistry |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 04 Oct 2019 06:16 |
| Last Modified: | 04 Oct 2019 06:16 |
| URI: | https://pred.uni-regensburg.de/id/eprint/13348 |
Actions (login required)
 |
View Item |
