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Title: Maximizing Electron Exchange in a [F 3] Cluster

Journal Article · · Journal of the American Chemical Society
DOI:https://doi.org/10.1021/jacs.5b12181· OSTI ID:1467658

The one-electron reduction of (tbsL)Fe3(thf)1 furnishes [M][(tbsL)Fe3] ([M]+ = [(18-C-6)K(thf)2]+ (1, 76%) or [(crypt-222)K]+ (2, 54%)). Upon reduction, the ligand tbsL6- rearranges around the triiron core to adopt an almost ideal C3-symmetry. Accompanying the (tbsL) ligand rearrangement, the THF bound to the neutral starting material is expelled, and the Fe–Fe distances within the trinuclear cluster contract by ~0.13 Å in 1. Variable-temperature magnetic susceptibility data indicates a well-isolated spin ground state that persists to room temperature. Slow magnetic relaxation is observed at low temperature as evidenced by the out-of-phase component of the alternating current (ac) magnetic susceptibility data and by the appearance of hyperfine splitting in the zero-field 57Fe Mössbauer spectra at 4.2 K. Analysis of the ac magnetic susceptibility yields an effective spin reversal barrier (Ueff) of 22.6(2) cm-1, nearly matching the theoretical barrier of 38.7 cm-1 calculated from the axial zero-field splitting parameter (D = -1.29 cm-1) extracted from the reduced magnetization data. A polycrystalline sample of 1 displays three sextets in the Mössbauer spectrum at 4.2 K (Hext = 0) which converge to a single six-line pattern in a frozen 2-MeTHF glass sample, indicating a unique iron environment and thus strong electron delocalization. The spin ground state and ligand rearrangement are discussed within the framework of a fully delocalized cluster exhibiting strong double and direct exchange interactions.

Research Organization:
Harvard Univ., Cambridge, MA (United States)
Sponsoring Organization:
USDOE Office of Science (SC)
Grant/Contract Number:
SC0008313
OSTI ID:
1467658
Journal Information:
Journal of the American Chemical Society, Vol. 138, Issue 7; ISSN 0002-7863
Publisher:
American Chemical Society (ACS)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 35 works
Citation information provided by
Web of Science

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Cited By (9)

Exposing the inadequacy of redox formalisms by resolving redox inequivalence within isovalent clusters journal July 2019
An iron ketimide single-molecule magnet [Fe 4 (NCPh 2 ) 6 ] with suppressed through-barrier relaxation journal January 2020
Iron-based trinuclear metal-organic nanostructures on a surface with local charge accumulation journal August 2018
Alkene Hydrogenations by Soluble Iron Nanocluster Catalysts journal February 2017
Electron Delocalization of Mixed-Valence Diiron Sites Mediated by Group 10 Metal Ions in Heterotrimetallic Fe-M-Fe (M=Ni, Pd, and Pt) Chain Complexes journal July 2018
Self-assembly of an organometallic Fe 9 O 6 cluster from aerobic oxidation of (tmeda)Fe(CH 2 t Bu) 2 journal January 2020
Redox behaviour of ([fc(NP i Pr 2 ) 2 ]Fe) 2 , formation of an iron–iron bond and cleavage of azobenzene journal January 2018
Alkene Hydrogenations by Soluble Iron Nanocluster Catalysts journal February 2017
Iron-based trinuclear metal-organic nanostructures on a surface with local charge accumulation text January 2018


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