Article (Scientific journals)
Experimental and Computational Study of the Structural and Electronic Properties of Fe II(2,20-bipyridine)(mes) 2 and [Fe II(2,20-bipyridine)(mes) 2] -, a Complex Containing a 2,20-Bipyridyl Radical Anion
Irwin, Mark; Jenkins, Rhiannon; Denning, Mark et al.
2010In Inorganic Chemistry, 49, p. 6160-6171
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Keywords :
x-ray diffraction; Mossbauer spectroscopy; magnetic properties
Abstract :
[en] 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(2,20 -bipyridine)(mes)2 (1; mes = 2,4,6-Me3C6H2) yielded the anionic complex [Fe(2,20 -bipyridine)(mes)2] - which was isolated as [K(2,2,2-crypt)][Fe(2,20 -bipyridine)(mes) 2](2) alongside the side-product [K(2,2,2-crypt)][Fe(mes)3] 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 (S Fe =2) and a π* orbital of the bipyridyl radical (Sbipy = 1/2). Structural data, M€ossbauer 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 2,20 -bipyridyl ligand for which magnetic, spectroscopic, and computational data indicate the presence of an unpaired electron in the π* antibonding orbital.
Disciplines :
Chemistry
Author, co-author :
Irwin, Mark;  Oxford University > Chemistry
Jenkins, Rhiannon;  Oxford University > Chemistry
Denning, Mark;  Oxford University > Chemistry
Kramer, Tobias;  Oxford University > Chemistry
Grandjean, Fernande ;  Université de Liège - ULiège > Département de physique > Département de physique
Long, Gary J;  Missouri University of Science and Technology > Chemistry
Herchel, Radovan;  Palacky University > Chemistry
Mc Gready, John;  Oxford University > Chemistry
Goicoechea, Jose;  Oxford University > Chemistry
Language :
English
Title :
Experimental and Computational Study of the Structural and Electronic Properties of Fe II(2,20-bipyridine)(mes) 2 and [Fe II(2,20-bipyridine)(mes) 2] -, a Complex Containing a 2,20-Bipyridyl Radical Anion
Publication date :
2010
Journal title :
Inorganic Chemistry
ISSN :
0020-1669
eISSN :
1520-510X
Publisher :
American Chemical Society, Washington, United States - District of Columbia
Volume :
49
Pages :
6160-6171
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 30 November 2012

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