Dataset Information

Solid-Phase Quasi-Intramolecular Redox Reaction of [Ag(NH₃)₂]MnO₄: An Easy Way to Prepare Pure AgMnO₂.

ABSTRACT: Two monoclinic polymorphs of [Ag(NH₃)₂]MnO₄ containing a unique coordination mode of permanganate ions were prepared, and the high-temperature polymorph was used as a precursor to synthesize pure AgMnO₂. The hydrogen bonds between the permanganate ions and the hydrogen atoms of ammonia were detected by IR spectroscopy and single-crystal X-ray diffraction. Under thermal decomposition, these hydrogen bonds induced a solid-phase quasi-intramolecular redox reaction between the [Ag(NH₃)₂]⁺ cation and MnO₄^- anion even before losing the ammonia ligand or permanganate oxygen atom. The polymorphs decomposed into finely dispersed elementary silver, amorphous MnO_x compounds, and H₂O, N₂ and NO gases. Annealing the primary decomposition product at 573 K, the metallic silver reacted with the manganese oxides and resulted in the formation of amorphous silver manganese oxides, which started to crystallize only at 773 K and completely transformed into AgMnO₂ at 873 K.

SUBMITTER: Fogaca LA

PROVIDER: S-EPMC8034774 | biostudies-literature | 2021 Mar

REPOSITORIES: biostudies-literature

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Publications

Solid-Phase Quasi-Intramolecular Redox Reaction of [Ag(NH3)2]MnO4: An Easy Way to Prepare Pure AgMnO2.

Fogaca Lara A LA Kováts Éva É Németh Gergely G Kamarás Katalin K Béres Kende A KA Németh Péter P Petruševski Vladimir V Bereczki Laura L Holló Berta Barta BB Sajó István E IE Klébert Szilvia S Farkas Attila A Szilágyi Imre M IM Kótai László L

Inorganic chemistry 20210301 6

Two monoclinic polymorphs of [Ag(NH3)2]MnO4 containing a unique coordination mode of permanganate ions were prepared, and the high-temperature polymorph was used as a precursor to synthesize pure AgMnO2. The hydrogen bonds between the permanganate ions and the hydrogen atoms of ammonia were detected by IR spectroscopy and single-crystal X-ray diffraction. Under thermal decomposition, these hydrogen bonds induced a solid-phase quasi-intramolecular redox ...[more]

PMID: 33647206

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Project description:Research on new reaction routes and precursors to prepare catalysts for CO2 hydrogenation has enormous importance. Here, we report on the preparation of the permanganate salt of the urea-coordinated iron(III), [hexakis(urea-O)iron(III)]permanganate ([Fe(urea-O)6](MnO4)3) via an affordable synthesis route and preliminarily demonstrate the catalytic activity of its (Fe,Mn)Ox thermal decomposition products in CO2 hydrogenation. [Fe(urea-O)6](MnO4)3 contains O-coordinated urea ligands in octahedral propeller-like arrangement around the Fe3+ cation. There are extended hydrogen bond interactions between the permanganate ions and the hydrogen atoms of the urea ligands. These hydrogen bonds serve as reaction centers and have unique roles in the solid-phase quasi-intramolecular redox reaction of the urea ligand and the permanganate anion below the temperature of ligand loss of the complex cation. The decomposition mechanism of the urea ligand (ammonia elimination with the formation of isocyanuric acid and biuret) has been clarified. In an inert atmosphere, the final thermal decomposition product was manganese-containing wuestite, (Fe,Mn)O, at 800 °C, whereas in ambient air, two types of bixbyite (Fe,Mn)2O3 as well as jacobsite (Fe,Mn)T-4(Fe,Mn)OC-62O4), with overall Fe to Mn stoichiometry of 1:3, were formed. These final products were obtained regardless of the different atmospheres applied during thermal treatments up to 350 °C. Disordered bixbyite formed first with inhomogeneous Fe and Mn distribution and double-size supercell and then transformed gradually into common bixbyite with regular structure (and with 1:3 Fe to Mn ratio) upon increasing the temperature and heating time. The (Fe,Mn)Ox intermediates formed under various conditions showed catalytic effect in the CO2 hydrogenation reaction with <57.6% CO2 conversions and <39.3% hydrocarbon yields. As a mild solid-phase oxidant, hexakis(urea-O)iron(III) permanganate, was found to be selective in the transformation of (un)substituted benzylic alcohols into benzaldehydes and benzonitriles.

Dataset Information

Solid-Phase Quasi-Intramolecular Redox Reaction of [Ag(NH₃)₂]MnO₄: An Easy Way to Prepare Pure AgMnO₂.

Publications

Solid-Phase Quasi-Intramolecular Redox Reaction of [Ag(NH<sub>3</sub>)<sub>2</sub>]MnO<sub>4</sub>: An Easy Way to Prepare Pure AgMnO<sub>2</sub>.

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