All-inorganic ferric wheel based on hexaniobate-anion linkers

Mark Baranov; Libi Polin; Nitai Leffler; Gregory Leitus; Alexander I Shames; Ira A Weinstock

doi:10.1039/d2dt00971d

All-inorganic ferric wheel based on hexaniobate-anion linkers

Dalton Trans. 2022 Jun 7;51(22):8600-8604. doi: 10.1039/d2dt00971d.

Authors

Mark Baranov¹, Libi Polin¹, Nitai Leffler¹, Gregory Leitus², Alexander I Shames³, Ira A Weinstock¹

Affiliations

¹ Department of Chemistry and the Ilse Katz Institute for Nanoscale Science & Technology, Ben-Gurion University of the Negev, Beer Sheva, 84105, Israel. iraw@bgu.ac.il.
² Chemical Research Support Unit, Weizmann Institute of Science, Rehovot 76100, Israel.
³ Department of Physics, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel.

PMID: 35593418
DOI: 10.1039/d2dt00971d

Abstract

Utilizing the inherent ability of Lindquist-type hexaniobate cluster-anions, [Nb₆O₁₉]^8-, to serve as oxo-donor ligands in complexes with transition-metal cations, we report the synthesis and characterization of the first all-inorganic "ferric" wheel, Li₄₈[(Nb₆O₁₉)₈Fe₈(OH)₈]·88H₂O, comprised of eight Fe atoms linked by eight hexaniobate cluster-anion ligands. Bond valence sum analysis of the X-ray structure and the synthesis conditions themselves indicate that the Fe atoms are in the +3 oxidation state. This is confirmed by magnetic susceptibility and electron paramagnetic resonance (EPR) measurements which indicate the presence of high spin (S = 5/2) Fe(III) ions. In addition, magnetic susceptibility measurements reveal long-range superexchange antiferromagnetic interactions between the hexaniobate-ligand separated Fe³⁺ ions (J = -0.22 cm^-1). More generally, the results suggest the use of hexaniobate cluster-anions as linkers in the synthesis of other two- or three-dimensional polyoxometalate framework structures.