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Issue 18, 2020
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An iron ketimide single-molecule magnet [Fe4(N[double bond, length as m-dash]CPh2)6] with suppressed through-barrier relaxation

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Abstract

Reaction of FeBr2 with 1.5 equiv. of LiN[double bond, length as m-dash]CPh2 and 2 equiv. of Zn, in THF, results in the formation of the tetrametallic iron ketimide cluster [Fe4(N[double bond, length as m-dash]CPh2)6] (1) in moderate yield. Formally, two Fe centers in 1 are Fe(I) and two are Fe(II); however, Mössbauer spectroscopy and SQUID magnetometry suggests that the [Fe4]6+ core of 1 exhibits complete valence electron delocalization, with a thermally-persistent spin ground state of S = 7. AC and DC SQUID magnetometry reveals the presence of slow magnetic relaxation in 1, indicative of single-molecule magnetic (SMM) behaviour with a relaxation barrier of Ueff = 29 cm−1. Remarkably, very little quantum tunnelling or Raman relaxation is observed down to 1.8 K, which leads to an open hysteresis loop and long relaxation times (up to 34 s at 1.8 K and zero field and 440 s at 1.67 kOe). These results suggest that transition metal ketimide clusters represent a promising avenue to create long-lifetime single molecule magnets.

Graphical abstract: An iron ketimide single-molecule magnet [Fe4(N [[double bond, length as m-dash]] CPh2)6] with suppressed through-barrier relaxation

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Supplementary files

Article information


Submitted
16 Mar 2020
Accepted
18 Apr 2020
First published
20 Apr 2020

This article is Open Access
All publication charges for this article have been paid for by the Royal Society of Chemistry

Chem. Sci., 2020,11, 4753-4757
Article type
Edge Article

An iron ketimide single-molecule magnet [Fe4(N[double bond, length as m-dash]CPh2)6] with suppressed through-barrier relaxation

A. W. Cook, J. D. Bocarsly, R. A. Lewis, A. J. Touchton, S. Morochnik and T. W. Hayton, Chem. Sci., 2020, 11, 4753
DOI: 10.1039/D0SC01578D

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