Structural, Spectroscopic, and Thermal Decomposition Features of [Carbonatotetraamminecobalt(III)] Iodide—Insight into the Simultaneous Solid-Phase Quasi-Intramolecular Redox Reactions

Abstract

[κ2-O,O′-Carbonatotetraamminecobalt(III)] iodide, or [Co(NH3)4CO3]I, named in this paper as compound 1, was prepared and characterized comprehensively with spectroscopic (IR, Raman and UV) and single-crystal X-ray diffraction methods. Compound 1 was orthorhombic, and isomorphous with the analogous bromide. The four ammonia ligands and the carbonate anion were coordinated to the central cobalt cation in a distorted octahedral geometry. The carbonate ion formed a four-membered symmetric planar chelate ring. The complex cations were bound to each other by N-H···O hydrogen bonds and formed zigzag sheets via an extended 2D hydrogen bond network. The complex cations and iodide ions were arranged into ion pairs and each cation bound its iodide pair through three hydrogen bonds. The thermal decomposition started with the oxidation of the iodide ion by CoIII in the solid phase resulting in [Co(NH3)4CO3] and I2. This intermediate CoII-complex in situ decomposed into Co3O4 and C-N bond containing intermediates. In inert atmosphere, CO or C-N bond containing compounds, and also, due to the in situ decomposition of CoCO3 intermediate, Co3O4 was formed. The quasi-intramolecular solid-phase redox reaction of [Co(NH3)4CO3] might have resulted in the formation of C-N bond containing compounds with substoichiometric release of ammonia and CO2 from compound 1. The C-N bond containing intermediates reduced Co3O4 into CoO and Co, whereas in oxygen-containing atmosphere, the end-product was Co3O4, even at 200 °C, and the endothermic ligand loss reaction coincided with the consecutive exothermic oxidation processes.

Hexakis(urea-O)iron Complex Salts as a Versatile Material Family: Overview of Their Properties and Applications

“…The solid phase quasi-intramolecular redox reactions generally occur at low temperatures (between 50–140 °C), and the reactions are exothermic; due to the solid-phase environment and low temperature, these redox reactions result in a disrupted lattice product (amorphous materials), which can crystallize in controlled size with postannealing. ,,− The oxidation power and reducing ability of the ligands in the solid phase are not equal to those parameters found in aqueous solutions. Accordingly, the urea as a reducing ligand will cause special effects in the gaseous environment, and various valence states of the metals may appear in the solid mixed oxides.…”

Insight into the Structure and Redox Chemistry of [Carbonatotetraamminecobalt(III)] Permanganate and Its Monohydrate as Co-Mn-Oxide Catalyst Precursors of the Fischer-Tropsch Synthesis

“…Since the peak at m/z = 44 may belong to CO 2 + and to N 2 O + as well, and both species have m/z = 28 and m/z = 16 fragments (N 2 /CO + and O + , respectively), it is not possible to separate the contributions of N 2 O (as ammonium nitrate decomposition product) and CO 2 (as carbonate decomposition product). The IR spectrum of the decomposition intermediate formed at 160 • C shows the presence of residual carbonate ion with ν s (C-O) at 1042 cm −1 , ν as (C-O) in the range 1406-1334 cm −1 (overlapped with a nitrate band located at ~1380 cm −1 [40], and δ(out of plane deformation) at 826 cm −1 (Figure 8). The position of the carbonate ion and the lack of high wavenumber C=O stretching mode bands in the spectrum of product I-160 show that the carbonate coordinated originally as a chelate became simple ionic due to the destruction of the original coordination sphere around Co III .…”

“…This reaction route led to various cobalt manganese spinels, which were found to be active catalysts for various industrially important processes. The appropriate selection of the ammine-coordinated cobalt and permanganate-containing precursors can result in the formation of Co x Mn 2−x O 4 type catalysts with Co to Mn ratio 1:1-3 with exact compositions and properties depending on the preparation conditions as well [4,27,[39][40][41][42]. With the use of [carbonatotetraamminecobalt(III)] permanganate (compound 1, Co(NH 3 ) 4 CO 3 ]MnO 4 , with Co to Mn stoichiometry 1:1, Mansouri et al prepared an excellent Fischer-Tropsch catalyst characterized with CoMn 2 O 4 composition [4].…”

Review on the Chemistry of [M(NH3)n](XO4)m (M = Transition Metal, X = Mn, Tc or Re, n = 1–6, m = 1–3) Ammine Complexes

“…The temperature-controlled decomposition of transition metal complexes containing redox-active central atoms, ligands, and anions in solid-phase quasi-intramolecular redox reactions has become a widely used method of preparing nano-sized oxides, nitrides, carbides, metals, and their alloys [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. The reducing ligands (pyridine, urea, or ammonia) and oxidizing anions containing precursors frequently give amorphous decomposition intermediates, which can be transformed into controlled-sized crystalline materials by heat treatment [7,[10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28].…”

“…The temperature-controlled decomposition of transition metal complexes containing redox-active central atoms, ligands, and anions in solid-phase quasi-intramolecular redox reactions has become a widely used method of preparing nano-sized oxides, nitrides, carbides, metals, and their alloys [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. The reducing ligands (pyridine, urea, or ammonia) and oxidizing anions containing precursors frequently give amorphous decomposition intermediates, which can be transformed into controlled-sized crystalline materials by heat treatment [7,[10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. Permanganate complexes and other tetraoxometallates result in the formation of various nano-sized mixed oxides, especially M A M B 2 O 4 spinels, including those with varying ratios of M A and M B cations at the tetrahedral or octahedral sites of the spinel lattice (M A being the cationic and M B the anionic metal component) [29].…”