Magnetic blocking in a linear iron(I) complex

Abstract

Single-molecule magnets that contain one spin centre may represent the smallest possible unit for spin-based computational devices. Such applications, however, require the realization of molecules with a substantial energy barrier for spin inversion, achieved through a large axial magnetic anisotropy. Recently, significant progress has been made in this regard by using lanthanide centres such as terbium(III) and dysprosium(III), whose anisotropy can lead to extremely high relaxation barriers. We contend that similar effects should be achievable with transition metals by maintaining a low coordination number to restrict the magnitude of the d-orbital ligand-field splitting energy (which tends to hinder the development of large anisotropies). Herein we report the first two-coordinate complex of iron(I), [Fe(C(SiMe3)3)2], for which alternating current magnetic susceptibility measurements reveal slow magnetic relaxation below 29 K in a zero applied direct-current field. This S =  complex exhibits an effective spin-reversal barrier of Ueff = 226(4) cm−1, the largest yet observed for a single-molecule magnet based on a transition metal, and displays magnetic blocking below 4.5 K.

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Figure 1: Preparation, structure and d-orbital splitting of the linear iron(I) complex [Fe(C(SiMe3)3)2].
Figure 2: Mössbauer spectra for crystalline 1 measured at 295 and 5 K.
Figure 3: Variable-temperature molar magnetic susceptibility and field-cooled versus zero-field cooled magnetization data.
Figure 4: Dynamic magnetic data for 1.
Figure 5: Variable-field magnetization data for 1.

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Acknowledgements

This research was funded by the National Science Foundation through grant CHE-1010002. We thank R. Nichiporuk for assistance with ESI/MS acquisition, T. Chantarojsiri, M. Nippe and S. Demir for experimental assistance and M. Fasulo for valuable discussions.

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J.M.Z., D.J.X. and J.R.L. planned and executed the synthesis, characterization and magnetic measurements, and analysed the resulting data. M.A. and F.N. performed calculations and analysed the resulting data. G.J.L. and F.G. analysed the Mössbauer spectra. All authors were involved in writing the manuscript.

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Correspondence to Jeffrey R. Long.

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The authors declare no competing financial interests.

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Crystallographic data for compound 1 (CIF 46 kb)

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Zadrozny, J., Xiao, D., Atanasov, M. et al. Magnetic blocking in a linear iron(I) complex. Nature Chem 5, 577–581 (2013). https://doi.org/10.1038/nchem.1630

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