Titlebar

Export bibliographic data
Literature by the same author
plus on the publication server
plus at Google Scholar

 

Controlled ligand distortion and its consequences for structure, symmetry, conformation and spin-state preferences of iron(ii) complexes

Title data

Kroll, Nicole ; Theilacker, Kolja ; Schoknecht, Marc ; Baabe, Dirk ; Wiedemann, Dennis ; Kaupp, Martin ; Grohmann, Andreas ; Hörner, Gerald:
Controlled ligand distortion and its consequences for structure, symmetry, conformation and spin-state preferences of iron(ii) complexes.
In: Dalton Transactions. Vol. 44 (13 October 2015) Issue 44 . - pp. 19232-19247.
ISSN 1477-9234
DOI: https://doi.org/10.1039/C5DT02502H

Project information

Project financing: Deutsche Forschungsgemeinschaft

Abstract in another language

The ligand-field strength in metal complexes of polydentate ligands depends critically on how the ligand backbone places the donor atoms in three-dimensional space. Distortions from regular coordination geometries are often observed. In this work, we study the isolated effect of ligand-sphere distortion by means of two structurally related pentadentate ligands of identical donor set, in the solid state (X-ray diffraction, 57Fe-Mössbauer spectroscopy), in solution (NMR spectroscopy, UV/Vis spectroscopy, conductometry), and with quantum-chemical methods. Crystal structures of hexacoordinate iron(II) and nickel(II) complexes derived from the cyclic ligand L1 (6-methyl-6-(pyridin-2-yl)-1,4-bis(pyridin-2-ylmethyl)-1,4-diazepane) and its open-chain congener L2 (N1,N3,2-trimethyl-2-(pyridine-2-yl)-N1,N3-bis(pyridine-2-ylmethyl) propane-1,3-diamine) reveal distinctly different donor set distortions reflecting the differences in ligand topology. Distortion from regular octahedral geometry is minor for complexes of ligand L2, but becomes significant in the complexes of the cyclic ligand L1, where trans elongation of Fe−N bonds cannot be compensated by the rigid ligand backbone. This provokes trigonal twisting of the ligand field. This distortion causes the metal ion in complexes of L1 to experience a significantly weaker ligand field than in the complexes of L2, which are more regular. The reduced ligand-field strength in complexes of L1 translates into a marked preference for the electronic high-spin state, the emergence of conformational isomers, and massively enhanced lability with respect to ligand exchange and oxidation of the central ion. Accordingly, oxoiron(IV) species derived from L1 and L2 differ in their spectroscopic properties and their chemical reactivity.

Further data

Item Type: Article in a journal
Refereed: Yes
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Inorganic Chemistry IV
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Inorganic Chemistry IV > Chair Inorganic Chemistry IV - Univ.-Prof. Dr. Birgit Weber
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry
Result of work at the UBT: No
DDC Subjects: 500 Science > 540 Chemistry
Date Deposited: 08 Jul 2020 06:15
Last Modified: 08 Jul 2020 06:15
URI: https://eref.uni-bayreuth.de/id/eprint/55722