Irwin, Mark and Jenkins, Rhiannon K. and Denning, Mark S. and Krämer, Tobias and Grandjean, Fernande and Long, Gary J. and Herchel, Radovan and McGrady, John E. and Goicoechea, Jose M. (2010) Experimental and Computational Study of the Structural and Electronic Properties of FeII(2,2′-bipyridine)(mes)2 and [FeII(2,2′-bipyridine)(mes)2]−, a Complex Containing a 2,2′-Bipyridyl Radical Anion. Inorganic Chemistry, 49 (13). pp. 6160-6171. ISSN 0020-1669

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Abstract

Addition of potassium metal and 2,2,2-crypt (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane) to a tetrahydrofuran (THF) solution of Fe(2,2′-bipyridine)(mes)2 (1; mes = 2,4,6-Me3C6H2) yielded the anionic complex [Fe(2,2′-bipyridine)(mes)2]− which was isolated as [K(2,2,2-crypt)][Fe(2,2′-bipyridine)(mes)2] (2) alongside the side-product [K(2,2,2-crypt)][Fe(mes)3]·C6H12 (3). A compositionally pure sample of 2 was obtained by dissolving a mixture of 2 and 3 in dry pyridine and layering the resulting solution with toluene. Solid state magnetic susceptibility measurements on 1 reveal Curie−Weiss paramagnetic behavior with a molar magnetic moment of 5.12(1) μB between 20 and 300 K, a value which is in line with the expected iron(II) spin-only value of 4.90 μB. The magnetic measurements carried out on 2 reveal more complex temperature dependent behavior consistent with intramolecular antiferromagnetic coupling (J = −46 cm−1) between the unpaired electrons of the iron(II) ion (SFe = 2) and a π* orbital of the bipyridyl radical (Sbipy = 1/2). Structural data, Mössbauer and electron paramagnetic resonance (EPR) spectroscopic measurements, and density functional theory (DFT) calculations are all consistent with this model of the electronic structure. To the best of our knowledge, species 2 represents the first crystallographically characterized transition metal complex of the 2,2′-bipyridyl ligand for which magnetic, spectroscopic, and computational data indicate the presence of an unpaired electron in the π* antibonding orbital.

Item Type:	Article
Keywords:	Experimental; Computational Study; Structural; Electronic Properties; FeII(2,2′-bipyridine)(mes)2; [FeII(2,2′-bipyridine)(mes)2]−; Complex; Containing; 2,2′-Bipyridyl Radical Anion;
Academic Unit:	Faculty of Science and Engineering > Chemistry Faculty of Science and Engineering > Research Institutes > Hamilton Institute
Item ID:	15533
Identification Number:	https://doi.org/10.1021/ic100817s
Depositing User:	Tobias Kraemer
Date Deposited:	21 Feb 2022 15:29
Journal or Publication Title:	Inorganic Chemistry
Publisher:	ACS Publications
Refereed:	Yes
URI:	Publisher
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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