Mapping the d-d Excited-State Manifolds of Transition Metal beta-Diiminato-Imido Complexes. Comparison of Density Functional Theory and CASPT2 Energetics
(2008) In The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory 112(50). p.12792-12798- Abstract
- Trigonal-planar, middle transition metal diiminato-imido complexes do not exhibit high-spin states, as might be naively expected on the basis of their low coordination numbers. Instead, the known Fe(III), Co(III), and Ni(III) complexes exhibit S = (3)/(2), S = 0, and S = (1)/(2), ground states, respectively. Kohn-Sham DFT calculations have provided a basic molecular orbital picture of these compounds as well as a qualitative rationale for the observed spin states. Reported herein are ab initio multiconfiguration second-order perturbation theory (CASPT2) calculations, which provide a relatively detailed picture of the d-d excited-state manifolds of these complexes. Thus, for a C-2v Fe-III(diiminato)(NPh) model complex, two near-degenerate... (More)
- Trigonal-planar, middle transition metal diiminato-imido complexes do not exhibit high-spin states, as might be naively expected on the basis of their low coordination numbers. Instead, the known Fe(III), Co(III), and Ni(III) complexes exhibit S = (3)/(2), S = 0, and S = (1)/(2), ground states, respectively. Kohn-Sham DFT calculations have provided a basic molecular orbital picture of these compounds as well as a qualitative rationale for the observed spin states. Reported herein are ab initio multiconfiguration second-order perturbation theory (CASPT2) calculations, which provide a relatively detailed picture of the d-d excited-state manifolds of these complexes. Thus, for a C-2v Fe-III(diiminato)(NPh) model complex, two near-degenerate states (B-4(2) and B-4(1)) compete as contenders for the ground state. Moreover, the high-spin sextet, two additional quartets and even a low-spin doublet all occur at <0.5 eV, relative to the ground state. For the Co(III) system, although CASPT2 reproduces an S = 0 ground state, as observed experimentally for a related complex, the calculations also predict two exceedingly low-energy triplet states; there are, however, no other particularly low-energy d-d excited states. In contrast to the Fe(III) and Co(III) cases, the Ni(III) complex has a clearly nondegenerate B-2(2) ground state. The CASPT2 energetics provide benchmarks against which we can evaluate the performance of several common DFT methods. Although none of the functionals examined perform entirely satisfactorily, the B3LYP hybrid functional provides the best overall spin-state energetics. (Less)
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- author
- Ghosh, Abhik ; Gonzalez, Emmanuel ; Tangen, Espen and Roos, Björn LU
- organization
- publishing date
- 2008
- type
- Contribution to journal
- publication status
- published
- subject
- in
- The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory
- volume
- 112
- issue
- 50
- pages
- 12792 - 12798
- publisher
- The American Chemical Society (ACS)
- external identifiers
-
- wos:000261652800009
- scopus:58149234955
- pmid:18433111
- ISSN
- 1520-5215
- DOI
- 10.1021/jp711159h
- language
- English
- LU publication?
- yes
- additional info
- The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Theoretical Chemistry (S) (011001039)
- id
- 15c81ce0-6fe1-4763-95a8-cf4d7bd9b6de (old id 1379243)
- date added to LUP
- 2016-04-01 13:02:17
- date last changed
- 2023-01-03 20:41:32
@article{15c81ce0-6fe1-4763-95a8-cf4d7bd9b6de,
abstract = {{Trigonal-planar, middle transition metal diiminato-imido complexes do not exhibit high-spin states, as might be naively expected on the basis of their low coordination numbers. Instead, the known Fe(III), Co(III), and Ni(III) complexes exhibit S = (3)/(2), S = 0, and S = (1)/(2), ground states, respectively. Kohn-Sham DFT calculations have provided a basic molecular orbital picture of these compounds as well as a qualitative rationale for the observed spin states. Reported herein are ab initio multiconfiguration second-order perturbation theory (CASPT2) calculations, which provide a relatively detailed picture of the d-d excited-state manifolds of these complexes. Thus, for a C-2v Fe-III(diiminato)(NPh) model complex, two near-degenerate states (B-4(2) and B-4(1)) compete as contenders for the ground state. Moreover, the high-spin sextet, two additional quartets and even a low-spin doublet all occur at <0.5 eV, relative to the ground state. For the Co(III) system, although CASPT2 reproduces an S = 0 ground state, as observed experimentally for a related complex, the calculations also predict two exceedingly low-energy triplet states; there are, however, no other particularly low-energy d-d excited states. In contrast to the Fe(III) and Co(III) cases, the Ni(III) complex has a clearly nondegenerate B-2(2) ground state. The CASPT2 energetics provide benchmarks against which we can evaluate the performance of several common DFT methods. Although none of the functionals examined perform entirely satisfactorily, the B3LYP hybrid functional provides the best overall spin-state energetics.}},
author = {{Ghosh, Abhik and Gonzalez, Emmanuel and Tangen, Espen and Roos, Björn}},
issn = {{1520-5215}},
language = {{eng}},
number = {{50}},
pages = {{12792--12798}},
publisher = {{The American Chemical Society (ACS)}},
series = {{The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory}},
title = {{Mapping the d-d Excited-State Manifolds of Transition Metal beta-Diiminato-Imido Complexes. Comparison of Density Functional Theory and CASPT2 Energetics}},
url = {{http://dx.doi.org/10.1021/jp711159h}},
doi = {{10.1021/jp711159h}},
volume = {{112}},
year = {{2008}},
}