DFT/TD-DFT investigation on Ir(III) complexes with N-heterocyclic carbene ligands : geometries, electronic structures, absorption, and phosphorescence properties
Copyright 2009 Wiley Periodicals, Inc.
| Veröffentlicht in: | Journal of computational chemistry. - 1984. - 31(2010), 3 vom: 15. Feb., Seite 628-38 |
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| 1. Verfasser: | |
| Weitere Verfasser: | , , , , |
| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2010
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| Zugriff auf das übergeordnete Werk: | Journal of computational chemistry |
| Schlagworte: | Journal Article |
| Zusammenfassung: | Copyright 2009 Wiley Periodicals, Inc. Iridium(III) complexes with N-heterocyclic (NHC) ligands including fac-Ir(pmb)(3) (1), mer-Ir(pmb)(3) (2), (pmb)(2)Ir(acac) (3), mer-Ir(pypi)(3) (4), and fac-Ir(pypi)(3) (5) [pmb = 1-phenyl-3H-benzimidazolin-2-ylidene, acac = acetoylacetonate, pypi = 1-phenyl-5H-benzimidazolin-2-ylidene; fac = facial, mer = meridional] were investigated theoretically. The geometry structures of 1-5 in the ground and excited state were optimized with restricted and unrestricted DFT (density functional theory) methods, respectively (LANL2DZ for Ir atom and 6-31G for other atoms). The HOMOs (highest occupied molecular orbitals) of 1-3 are composed of d(Ir) and pi(phenyl), while those of 4 and 5 are contributed by d(Ir) and pi(carbene). The LUMOs (lowest unoccupied molecular orbitals) of 1, 2, 4, and 5 are localized on carbene, but that of 3 is localized on acac. The calculated lowest-lying absorptions with TD-DFT method based on Perdew-Burke-Erzenrhof (PBE) functional of 1 (310 nm), 2 (332 nm), and 3 (347 nm) have ML(carbene)CT/IL(phenyl-->carbene)CT (MLCT = metal-to-ligand charge transfer; ILCT = intraligand charge transfer) transition characters, whereas those of 4 (385 nm) and 5 (389 nm) are assigned to ML(carbene)CT/IL(carbene-->carbene)CT transitions. The phosphorescences calculated by TD-DFT method with PBE0 functional of 1 (386 nm) and 2 (388 nm) originate from (3)ML(carbene)CT/(3)IL(phenyl-->carbene)CT excited states, but those of 4 (575 nm) and 5 (578 nm) come from (3)ML(carbene)CT/(3)IL(carbene-->carbene)CT excited states. The calculated results showed that the carbene and phenyl groups act as two independent chromophores in transition processes. Compared with 1 and 2, the absorptions of 4 and 5 are red-shifted by increasing the effective pi-conjugation groups near the C(carbene) atom. We predicated that (pmb)(2)Ir(acac) is nonemissive, because the LUMO of 3 is contributed by the nonemissive acac ligand |
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| Beschreibung: | Date Completed 25.06.2010 Date Revised 04.01.2010 published: Print Citation Status PubMed-not-MEDLINE |
| ISSN: | 1096-987X |
| DOI: | 10.1002/jcc.21360 |