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The 1 : 1 type double salt of AgNO3 and NH4NO3 (NH4NO3 ⋅ AgNO3, compound 1) was prepared and its Raman spectrum was evaluated. IR and far-IR spectra of compound 1 and its deuterated analog (ND4NO3 ⋅ AgNO3, compound 1-D) were also studied. We identified two types of nitrate ions, one had a relatively strong, whereas the other is only weakly hydrogen bonded to the surrounding ammonium ions. The thermal decomposition features of compound 1 and its formation mechanism from [Ag(NH3)2]MnO4 (compound 2) at 80 °C with consecutive aqueous leaching of the decomposition residue has been elucidated. The solid phase decomposition product of compound 2 is presumably [Ag(NH3)NO3] (compound 3), which disproportionates into AgNO3 and [Ag(NH3)2]NO3 (compound 4). Compound 4 thermally decomposes in the solid phase into Ag+MnOx, while in aqueous solution its hydrolysis results in NH4NO3, which crystallizes out with an equimolar amount of AgNO3 formed during the disproportionation as compound 1. © 2021 The Authors. Zeitschrift für anorganische und allgemeine Chemie published by Wiley-VCH GmbH

This study aims to describe the thermal decomposition of two solvatomorphs of decakis(dimethylammonium) dihydrogendodecatungstate ((Me2NH2)10H2W12O42·10H2O and 11 H2O) under inert and oxidizing atmospheres. Thermal studies have been done by TG-MS, TG-DSC-MS, XRD and IR methods in both synthetic air and helium atmospheres. The general characteristics of thermal decomposition are similar for both solvatomorphs. Minor differences could be observed in the resolution and shifting of the decomposition peak temperatures depending on the heating rate or atmosphere used. The first step of decomposition is endothermic in both atmospheres and involves 2 and 5 water molecule elimination with ~ 150 and ~ 120 °C peak temperatures for the decahydrate and undecahydrate, respectively. The elimination of further water and dimethylamine was observed with increasing the temperature, as well as the disruption of the lattice of compounds. Until 300 °C, these processes are endothermic in both atmospheres, and the further decomposition processes at higher temperatures are left endothermic in helium, but become exothermic in synthetic air atmosphere. In helium atmosphere, above 350 °C, a solid-phase quasi-intramolecular redox reaction takes place when the dimethylamine degradation products react with the W=O bonds with formation of oxidative coupling products of the organic fragments and reduced tungsten oxide with WO~2.93 composition. In synthetic air, above 350 °C, burning of organic fragments takes place, there are no oxidative coupling products and reduced tungsten oxide formation, and the end product of decomposition is monoclinic WO3.

Two polymorphs and a solvatomorph of a new dimethylammonium polytungstate—decakis(dimethylammonium) dihydrogendodecatungstate, (Me2NH2)10(W12O42)·nH2O (n = 10 or 11)—have been synthesized. Their structures were characterized by single-crystal X-ray diffraction and solid-phase NMR methods. The shape of the dodecatungstate anions is essentially the same in all three structures, their interaction with the cations and water of crystallization, however, is remarkably variable, because the latter forms different hydrogen-bonded networks, and provides a highly versatile matrix. Accordingly, the N–H⋯O and C–H⋯O hydrogen bonds are positioned in each crystal lattice in a variety of environments, characteristic to the structure, which can be distinguished by solid-state 1H-CRAMPS, 13C, 15N CP MAS and 1H–13C heteronuclear correlation NMR. Thermogravimetry of the solvatomorphs also reflect the difference and multiformity of the environment of the water molecules in the different crystal lattices. The major factors behind the variability of the matrix are the ability of ammonium cations to form two hydrogen bonds and the rigidity of the polyoxometalate anion cage. The positions of the oxygen atoms in the latter are favourable for the formation of bifurcated and trifurcated cation–anion hydrogen bonds, some which are so durable that they persist after the crystals are dissolved in water, forming ion associates even in dilute solutions. The H atom involved in furcated hydrogen bonds cannot be exchanged by deuterium when the compound is dissolved in D2O. An obvious consequence of the versatility of the matrix is the propensity of these compounds to form multiple polymorphs.

Detailed vibrational (IR, Raman, far-IR) and thermal (TGA, TG–MS, DSC) analysis has been performed on di[κ1O,κ2O-carbonatotetraamminecobalt(III)] sulfate trihydrate, ([Co(NH3)4CO3]2SO4·3H2O (1). Its isothermic heating at 100 °C leads to formation of [Co(NH3)4CO3]2SO4 (compound 2). UV and IR studies showed that the distorted octahedral arrangement around cis-O2CoN4 core in compound 1 does not change during dehydration, which explains the reversible water loss and ability of compound 2 to rehydrate into compound 1. Compound 2 decomposes at ~ 240 °C in inert atmosphere giving final decomposition products, which are two modifications of nanosized metallic cobalt (hcp-15 nm, fcc-250 nm) and CoO (55 nm). The redox reaction results in N2 as an ammonia oxidation product. The decomposition intermediate is a cobalt(II) compound, Co2O1,14+δ(SO4)0.86 (δ = the oxygen surplus due to the presence of 2.8% of Co(III) ion). The same reaction in air atmosphere resulted in Co2O1.25+δ(SO4)0.75 (δ = the oxygen surplus due to the presence of 5.3% of Co(III) ion (compound 3a). Compound 3a is oxidized in air at 793 °C into Co3O4. The compound 3a exhibits catalytic activity in photodegradation in Congo red. The photodegradation process follows pseudo-first-order kinetic (kapp = 1.0 and 7.0. at pH = 3.4 and 5.25, respectively).

Two polymorphs and a solvatomorph of a new dimethylammonium polytungstate-decakis(dimethylammonium) dihydrogendodecatungstate, (Me

This work aims to evaluate the Cr(VI) removal efficiency and adsorption capacity of the raw coconut fiber from synthetic aqueous solutions through the operational parameters as well as to r...

Compounds containing redox active permanganate anions and complexed silver cations with reducing pyridine ligands are used not only as selective and mild oxidants in organic chemistry but as precursors for nanocatalyst synthesis in low-temperature solid-phase quasi-intramolecular redox reactions. Here we show a novel compound (4Agpy2MnO4·Agpy4MnO4) that has unique structural features including (1) four coordinated and one non-coordinated permanganate anion, (2) κ1O-permanganate coordinated Ag, (3) chain-like [Ag(py)2]+ units, (4) non-coordinated ionic permanganate ions and an [Ag(py)4]+ tetrahedra as well as (5) unsymmetrical hydrogen bonds between pyridine α-CHs and a permanganate oxygen. As a result of the oxidizing permanganate anion and reducing pyridine ligand, a highly exothermic reaction occurs at 85 °C. If the decomposition heat is absorbed by alumina or oxidation-resistant organic solvents (the solvent absorbs the heat to evaporate), the decomposition reaction proceeds smoothly and safely. During heating of the solid material, pyridine is partly oxidized into carbon dioxide and water; the solid phase decomposition end product contains mainly metallic Ag, Mn3O4 and some encapsulated carbon dioxide. Surprisingly, the enigmatic carbon-dioxide is an intercalated gas instead of the expected chemisorbed carbonate form. The title compound is proved to be a mild and efficient oxidant toward benzyl alcohols with an almost quantitative yield of benzaldehydes.

© 2019, The Author(s). A simple synthetic method was developed to prepare 4[Agpy2ClO4]·[Agpy4]ClO4 in a low-temperature decomposition process of [Agpy4]ClO4. A detailed IR, Raman and far-IR study including factor group analysis has been performed, and the assignation of bands is given. The compound decomposes quickly with a multistep ligand loss process with the formation of [Agpy2]ClO4 and AgClO4 intermediates and AgCl as an end product around ~ 85, ~ 350 and 450 °C, respectively. During the first decomposition step, a small fraction of the ligands is lost in a redox reaction: perchlorate oxidizes the pyridine, forming carbon, carbon dioxide, water and NO, while it itself is reduced into AgCl. In the next step, when AgClO4 forms after complete ligand loss and reacts with the carbon formed in the degradation of pyridine at lower temperatures and produces NO, CO2 and H2O. This reaction becomes possible because the AgCl formed in the redox reactions makes a eutectic melt with AgClO4 in situ, which is a favorable medium for the carbon oxidation reaction. AgCl is known to reduce the temperature of decomposition of AgClO4, in which process forms AgCl as well as O2 and so is an autocatalytic process. The loss and degradation of pyridine ligand are endothermic; the redox reactions including carbon oxidation and AgClO4 decomposition into AgCl and O2 are exothermic. The amount of absorbed/evolved heats corresponding to these processes was determined by DSC both under N2 and O2 atmospheres.

Compounds containing redox active permanganate anions and complexed silver cations with reducing pyridine ligands are used not only as selective and mild oxidants in organic chemistry but as precursors for nanocatalyst synthesis in low-temperature solid-phase quasi-intramolecular redox reactions. Here we show a novel compound (4Agpy

A novel nitrogen containing 3 H -1, 2, 4-triazole-3-thione-2, 4-dihydro-4-[(2-hydroxy-4-methoxyphenyl) methylene]-amino ligand (H 2 L) was synthesized using an equimolar ratio of 4-amino-1, 2, 4-triazole-3-thione and 2-hydroxy-4-methoxybenzaldehyde. A series of Mn (II), Fe (II), Co (II), Ni (II), Cu (II), Zn (II), Cd (II) transition metal complexes were synthesized using the ligand. The synthesized ligand and transition metal complexes were characterized by using IR, 1 H NMR, 13 C NMR, Mass spectrometry, UV, XRD and TGA investigation methods. Spectral data suggests that the ligand acts as a tridentate SNO donor. Further, the synthesized H 2 L ligand and their metal complexes were screened for antimicrobial activity. The results of biological activities showed that the metal complexes have higher antifungal as well as antibacterial activity as compared to the parent H 2 L ligand against the tested microbes.