Experimental spin-crossover investigations on charged and neutral iron(II) complexes with 4-substituted-2,6-bis-(benzimidazol-2′-yl) pyridine
- authored by
- M. Enamullah, F. Renz, U. El-Ayaan, G. Wiesinger, W. Linert
- Abstract
4-X-2,6-bis-(benzimidazol-2′-yl)-pyridine (X-bzimpy; X = H, Cl, OH) molecules coordinate with iron(II) as tridentate ligands forming complexes of distorted octahedral symmetry. The imino-hydrogen of the coordinated ligand of the complexes, [Fe(X-bzimpy)2]2+ is deprotonated in triethylamine solution. The deprotonated complexes, [Fe(X-bzimpyH-1)2] as well as [Fe(X-bzimpy)2]2+ were investigated by UV-VIS and FT-IR, Moessbauer spectroscopy. Quantum-mechanical calculations of the different species were performed and the derived parameters found to be in good agreement with the measured ones. The solid deprotonated complexes, showing in general thermal induced spincrossover, are predominantly at their low-spin (LS) state at room temperature in solid state. In contrast, a pronounced spin-crossover can be observed in methanolic solution. Thermodynamic parameters for [Fe(II-bzimpy)2]2+ and [Fe(H-bzimpyH-1)2] are derived in methanolic solution as ΔH and ΔS as 22.7 ± 0.6, 25.6 ± 1.2 kJ/mol and 85.1 ± 2.1, 92.8 ± 4.3 J/K/mol, respectively. In solid state for [Fe(H-bzimpy)2]2+, ΔH and ΔS were 13.3 ± 2.4 kJ/mol and 42.5 ± 8.6 J/K/mol, respectively.
- Organisation(s)
-
Institute of Inorganic Chemistry
- External Organisation(s)
-
TU Wien (TUW)
Jahangirnagar University
- Type
- Article
- Journal
- Vibrational spectroscopy
- Volume
- 14
- Pages
- 95-104
- No. of pages
- 10
- ISSN
- 0924-2031
- Publication date
- 03.1997
- Publication status
- Published
- Peer reviewed
- Yes
- ASJC Scopus subject areas
- Spectroscopy
- Electronic version(s)
-
https://doi.org/10.1016/S0924-2031(96)00042-2 (Access:
Unknown)
