Thermal decomposition and spectral characterization of di[carbonatotetraamminecobalt(III)] sulfate trihydrate and the nature of its thermal decomposition products

Abstract

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).

Solid-Phase “Self-Hydrolysis” of [Zn(NH3)4MoO4@2H2O] Involving Enclathrated Water—An Easy Route to a Layered Basic Ammonium Zinc Molybdate Coordination Polymer

“…UV spectra was measured on a Jasco V-670 UV–Vis spectrometer (JASCO Co., Oklahoma City, OK, USA) as it was given previously [ 22 , 34 ]…”

“…UV spectra was measured on a Jasco V-670 UV-Vis spectrometer (JASCO Co., Oklahoma City, OK, USA) as it was given previously [22,34] Low-temperature (−196.15 • C) N 2 adsorption measurements were performed after 24 h degassing at 110 • C on a NOVA 2000e (Quantachrome, Boynton Beach, FL, USA) automatic volumetric instrument. The apparent surface area S BET was determined using the Brunauer-Emmett-Teller (BET) model [35].…”

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

“…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. − Reduction of AgMnO 4 to {AgMnO x } ( 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 and in the combustion of N-heterocycles and chlorinated compounds (Körbl catalysts) . Because of the high reactivity of silver permanganate, however, control of the thermal decomposition process is difficult and production of the above-mentioned catalysts on a large scale has remained a serious challenge.…”

AgNO3⋅NH4NO3 – an enigmatic double‐salt type “decomposition intermediate” of diamminesilver(I) permanganate

“…The compound 1 was prepared in the thermal decomposition reaction of compound 2 and the aqueous leaching of the decomposition residue following the method given in. [7] The detailed description of the applied instruments can be found in our previous publications: [11][12][13][14][15][16] IR (Bruker Alpha FT-IR spectrometer attenuated total reflection mode, 2 cm À 1 resolution), far-IR (BioRad-Digilab FTS-60 A, attenuated reflection mode, 4 cm À 1 resolution) UV(Jasco V-670 UV-Vis spectrophotometer equipped with NV-470 type integrating sphere), Raman (Horiba Jobin-Yvon LabRAM-type microspectrometer, l 532 nm Nd-YAG and 785 nm diode laser, an Olympus BX-40 optical microscope), and PXRD (Philips PW-1050 Bragg-Brentano parafocusing goniometer with Cu tube), TG-MS (TA Instruments SDT Q600 thermal analyzer coupled to Hiden Analytical HPR-20/QIC mass spectrometer), DSC (Perkin Elmer Diamond DSC).…”