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 MnOx 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.
Highlights
IntroductionUsing pyridine as a ligand/reducing agent results in complexes that during heating decompose into Ag/ Mn3O4 composites without the formation of AgMnOx compounds.[4,10] there is no information about the reductive thermal decomposition of silver permanganate ammonia (NH3) complexes, other transition-metal permanganate complexes could be transformed into spinel-like mixed oxides (MMn2O4, where M = Cu, Zn, and Cd).[11−14] Our previous successful work on the synthesis and studies on the decomposition of compounds having redox-active cationic/anionic parts[3,4,10] prompted us to study ammonia complexes of silver permanganate as potential precursors in the low-temperature (
Solid-phase quasi-intramolecular redox reactions of compounds containing redox-active cations and anions ensure an easy way to prepare nanosized transition-metal oxides, which can be used as catalysts and sensors.[1−5] Reduction of AgMnO4 to {AgMnOx} (x = 2−3; formulas given in { } mean materials with known chemical but unknown phase compositions) type materials plays a key role in the preparation of highly efficient catalysts in CO oxidation[6] and in the combustion of Nheterocycles and chlorinated compounds (Körbl catalysts).[7]
There is no information about the reductive thermal decomposition of silver permanganate ammonia (NH3) complexes, other transition-metal permanganate complexes could be transformed into spinel-like mixed oxides (MMn2O4, where M = Cu, Zn, and Cd).[11−14] Our previous successful work on the synthesis and studies on the decomposition of compounds having redox-active cationic/anionic parts[3,4,10] prompted us to study ammonia complexes of silver permanganate as potential precursors in the low-temperature (
Summary
Using pyridine as a ligand/reducing agent results in complexes that during heating decompose into Ag/ Mn3O4 composites without the formation of AgMnOx compounds.[4,10] there is no information about the reductive thermal decomposition of silver permanganate ammonia (NH3) complexes, other transition-metal permanganate complexes could be transformed into spinel-like mixed oxides (MMn2O4, where M = Cu, Zn, and Cd).[11−14] Our previous successful work on the synthesis and studies on the decomposition of compounds having redox-active cationic/anionic parts[3,4,10] prompted us to study ammonia complexes of silver permanganate as potential precursors in the low-temperature (
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
