Magneto-structural analysis of Iron(III) Keggin polyoxometalates

Identifier:  imarina:5131441

Handle: https://hdl.handle.net/20.500.11797/imarina5131441

Authors:  Bandeira, Nuno A G; Sadeghi, Omid; Woods, Toby J; Zhang, Yuan-Zhu; Schnack, Juergen; Dunbar, Kim; Nyman, May; Bo, Caries

Abstract:
A computational study and magnetic susceptibility measurements of three homonuclear Fe(III) Keggin structures are herein presented: the [FeO4@Fe12F24(μ−OCH3)12]5− anion (1), the [Bi6{FeO4@Fe12O12(OH)12}(μ-O2CCCl3)12]+ cation (2) and its polymorph [Bi6{FeO4@Fe12O12(OH)10(H2O)2}(μ-O2CCF3)10]3+ (3). These results are contrasted with the exchange interactions present in the previously characterized [Fe6(OH)3Ge2W18O68(OH)6]11− and [H12As4Fe8W30O120(H2O)2]4− anions. The computational analysis shows that the most significant antiferromagnetic spin coupling takes place at the junction between each of the {Fe3O6(OH)3}/{Fe3F6(OCH3)3} framework motifs, a possibility that had been previously discarded in the literature on the basis of the Fe−Fe distances. For all the examined iron(III) Keggin structures, it is found that the magnitude of the magnetic couplings within each structural subunit follows the same trend.