Article (Scientific journals)
Slow Magnetic Relaxation in a Series of Non-Heme Trigonal Pyramidal Iron(II) Pyrrolide Complexes
Harmann, Hill E; Harris, T David; Freedman, Danna E et al.
2010In Journal of the American Chemical Society, 132, p. 18115
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Keywords :
Crystal structure; magnetic properties; Mossbauer spectroscopy
Abstract :
[en] We present a family of novel non-heme trigonal pyramidal iron(II) complexes supported by tris(pyrrolyl-α-methyl)amine ligands of the form [M(solv)n][(tpaR)Fe] (M = Na, R = tert-butyl (1), phenyl (4); M = K, R = mesityl (2), 2,4,6-triisopropylphenyl (3), 2,6-difluorophenyl (5)) and their characterization by X-ray crystallography, cyclic voltammetry, and Mössbauer spectroscopy. Expanding on the initial discovery of slow magnetic relaxation in the recently reported mesityl derivative 2, we report the static and dynamic magnetic properties of a homologous series of high-spin mononuclear iron(II) complexes that exhibit this intriguing behavior. Magnetization experiments reveal large, negative zero-field splitting parameters of D = −48, −40, −36, −26 and −6.2 cm−1 for 1-5, respectively. In the case of 2,6-difluorophenyl 5, high-field EPR experiments provide an independent determination of the zero-field splitting parameters (D = −4.397(9)) that are in reasonable agreement with the magnetization data. Ac susceptibility measurements indicate field-dependent, thermally-activated spin reversal barriers in complexes 1, 2 and 4 of Ueff = 60, 42 and 25 cm−1, respectively. In the case of 1, this value constitutes the highest spin-reversal barrier observed for a mononuclear transition metal complex, a property that has broad implications for the design of molecules that can potentially store and process magnetic information.
Disciplines :
Chemistry
Author, co-author :
Harmann, Hill E;  Berkeley University of California - UC Berkeley > Chemistry
Harris, T David;  Berkeley University of California - UC Berkeley > Chemistry
Freedman, Danna E;  Berkeley University of California - UC Berkeley > Chemistry
Fong, H.;  Berkeley University of California - UC Berkeley > Chemistry
Chang, A.;  Berkeley University of California - UC Berkeley > Chemistry
Rinehart, Jeffrey D;  Berkeley University of California - UC Berkeley > Chemistry
Grandjean, Fernande ;  Université de Liège - ULiège > Département de physique > Département de physique
Ozarowski, Andrew;  National Magnet Laboratory Florida
Long, Gary J;  Missouri University of Science and Technology > Chemistry
Long, Jeffrey R;  Berkeley University of California - UC Berkeley > Chemistry
Chang, Christopher;  University of California-Berkeley > Chemist6ry
Language :
English
Title :
Slow Magnetic Relaxation in a Series of Non-Heme Trigonal Pyramidal Iron(II) Pyrrolide Complexes
Publication date :
2010
Journal title :
Journal of the American Chemical Society
ISSN :
0002-7863
eISSN :
1520-5126
Publisher :
American Chemical Society, Washington, United States - District of Columbia
Volume :
132
Pages :
18115
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 12 January 2011

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