Weber AK, Panthöfer M, Möller A. Reactivity of FeMoO
4 in CsCl Fluxes and Formation of the Salt-Inclusion Type of Compounds.
Inorg Chem 2022;
61:10108-10115. [PMID:
35709382 DOI:
10.1021/acs.inorgchem.2c01195]
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Abstract
The reactivity of FeMoO4 in CsCl fluxes has been investigated by thermal analysis and chemical reactions in evacuated silica ampules. The products have been characterized by ex situ X-ray diffraction methods. Metathesis reactions involving CsCl lead to the formation of Cs2Fe2(MoO4)3 and the salt adduct Cs2FeCl4·CsCl. A side reaction has been observed, which is associated with a decomposition of [MoO4]2- in CsCl fluxes yielding Cs2Mo2O7·CsCl, which contains the rare pyromolybdate anion, [Mo2O7]2-, located in the center of a ∞2[CsCl] hetero-honeycomb arrangement. This salt-inclusion type of compound has been studied further in terms of its formation starting from Cs2MoO4, MoO3, and CsCl. The intermediate adduct phase, Cs2MoO4·MoO3, contains uncharged ∞1[MoO2O2/2] chains that react with CsCl at elevated temperatures to Cs2Mo2O7·CsCl. Furthermore, the site preference for alkaline-metal cations (K+, Rb+, and Cs+) has been evaluated for a mixed substitution series. In accordance with the Pearson concept, the polarizability of the respect cation outweighs any size differences for the occupancy of the salt-intergrowth motif, the honeycomb part of the structure.
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