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A DFT and Mössbauer spectroscopy investigation of spin‐crossover iron( II ) complexes with 2,6‐bis( 1H ‐imidazol‐2‐yl)pyridines
Ist Teil von
International journal of quantum chemistry, 2023-09, Vol.123 (21)
Ort / Verlag
Hoboken: Wiley Subscription Services, Inc
Erscheinungsjahr
2023
Quelle
Wiley-Blackwell Journals
Beschreibungen/Notizen
Abstract
A quantum chemical study was carried out for a number of iron(II) complexes [FeL
2
]A
i
·
n
H
2
O (L = 2,6‐bis(1
H
‐imidazole‐2‐yl)pyridine (L
1
); 2,6‐(4,5‐dimethyl‐1
H
‐imidazole‐2‐yl)pyridine (L
2
); 2,6‐bis(1
H
‐benzimidazole‐2‐yl)pyridine (L
3
); A = ReO
4
−
, B
10
H
10
2−
, B
12
H
12
2−
;
n
= 0–2). These complexes exist in the low spin (LS) form
1
A
1
(total electron spin S = 0) at room temperature and switch to the high spin (HS) form
5
T
2
(S = 2) upon heating. The experimental isomeric shift and quadrupole splitting values for compounds with L
2
exceed those for compounds with L
1
and L
3
by <0.02> mm/s and <0.1> mm/s, respectively (for LS forms). Such a discrepancy between MS parameters can be explained by the assumption that chemical bonding between the iron ion and the surrounding nitrogen atoms in the compounds with L
2
may be more ionic in character than that in the compounds with L
1
and L
3
. At the same time, the results obtained with the TPSSh hybrid meta‐GGA functional gave a better agreement with the experimental data than those obtained with the B3LYP exchange‐correlation functional.