Tuning Fe-Se Tetrahedral Frameworks by a Combination of [Fe(en)3]2+ Cations and Cl- Anions

Eranga H Gamage; Joshua T Greenfield; Colin Unger; Saeed Kamali; Judith K Clark; Colin P Harmer; Liang Luo; Jigang Wang; Michael Shatruk; Kirill Kovnir

doi:10.1021/acs.inorgchem.0c01727

Tuning Fe-Se Tetrahedral Frameworks by a Combination of [Fe(en)₃]²⁺ Cations and Cl^- Anions

Inorg Chem. 2020 Sep 21;59(18):13353-13363. doi: 10.1021/acs.inorgchem.0c01727. Epub 2020 Sep 1.

Authors

Eranga H Gamage^{1

2}, Joshua T Greenfield³, Colin Unger³, Saeed Kamali^{4

5}, Judith K Clark⁶, Colin P Harmer^{1

2}, Liang Luo^{2

7}, Jigang Wang^{2

7}, Michael Shatruk^{6

8}, Kirill Kovnir^{1

2}

Affiliations

¹ Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States.
² Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, United States.
³ Department of Chemistry, University of California, Davis, Davis, California 95616, United States.
⁴ Mechanical, Aerospace & Biomedical Engineering Department, University of Tennessee Space Institute, Tullahoma, Tennessee 37388, United States.
⁵ Department of Physics and Astronomy, Middle Tennessee State University, Murfreesboro, Tennessee 37132, United States.
⁶ Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.
⁷ Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States.
⁸ National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States.

PMID: 32872773
DOI: 10.1021/acs.inorgchem.0c01727

Abstract

A one-dimensional (1D) chain compound ${[{Fe(en)}_{3}]}_{3} {({FeSe}_{2})}_{4} {Cl}_{2}$ (en = ethylenediamine), featuring tetrahedral FeSe₂ chains separated by [Fe(en)₃]²⁺ cations and Cl^- anions, has been synthesized by a low temperature solvothermal method using simple starting materials. The degree of distortion in the Fe-Se backbone is similar to previously reported compounds with isolated 1D FeSe₂ chains. ⁵⁷Fe Mössbauer spectroscopy reveals the mixed-valent nature of [Fe(en)₃]₃(FeSe₂)₄Cl₂ with Fe³⁺ centers in the [FeSe₂]^- chains and Fe²⁺ centers in the [Fe(en)₃]²⁺ complexes. SQUID magnetometry indicates that ${[{Fe(en)}_{3}]}_{3} {({FeSe}_{2})}_{4} {Cl}_{2}$ is paramagnetic with a reduced average effective magnetic moment, μ_eff = 9.51 μ_B per formula unit, and a negative Weiss constant, θ = -10.9(4) K, indicating antiferromagnetic (AFM) nearest neighbor interactions within the [FeSe₂]^- chains. Weak antiferromagnetic coupling between chains, combined with rather strong intrachain AFM coupling, leads to spin-glass behavior at low temperatures, as indicated by a frequency shift of the peak observed at 3 K in AC magnetic measurements. A combination of [Fe(en)₃]²⁺ and Cl^- ions is also capable of stabilizing mixed-valent 2D Fe-Se puckered layers in the crystal structure of [Fe(en)₃]₄(Fe₁₄Se₂₁)Cl₂, where Fe₁₄Se₂₁ layers have a unique topology with large open pores. Property measurements of [Fe(en)₃]₄(Fe₁₄Se₂₁)Cl₂ could not be performed due to the inability to either grow large crystals or synthesize this material in single-phase form.