The reactivity of coordinated and uncoordinated chromate ions in the quasi-intramolecular redox reactions of [pentaamminechromatocobalt(iii)] chloride and chromate resulting in tuneable cobalt-chromium spinel oxide catalysts.
10 affiliations
- 1Institute of Materials and Environmental Chemistry, HUN-REN Research Centre for Natural Sciences Budapest Hungary [email protected] [email protected] [email protected] [email protected] [email protected] [email protected].
- 2Department of Physical Chemistry and Materials Science, Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics Budapest Hungary.
- 3Laboratory of Structural Chemistry and Biology, Institute of Chemistry, ELTE Eötvös Loránd University Budapest Hungary [email protected].
- 4HUN-REN-ELTE Protein Modelling Research Group Budapest Hungary.
- 5Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University 1-1 Minami-Osawa, Hachi-Oji Tokyo 192-0397 Japan [email protected].
- 6Department of Organic Chemistry and Technology, Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics Budapest Hungary [email protected].
- 7Division of Materials Chemistry, Ruđer Bošković Institute Zagreb Croatia [email protected].
- 8Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University Skopje Republic of North Macedonia [email protected].
- 9Institute of Chemistry, ELTE Eötvös Loránd University Budapest Hungary [email protected].
- 10Faculty of Physical Chemistry, University of Belgrade Belgrade Serbia [email protected] [email protected] [email protected].
Abstract
The synthesis routes, crystal and molecular structures, and controlled thermal decomposition reactions of two [pentamminecobalt(iii) compounds having a coordinated chromate ion, [Co(NH₃)₅CrO₄]Cl (compound 1) and [Co(NH₃)₅CrO₄]₂CrO₄ (compound 2) were studied experimentally. Quantum chemical optimizations and QTAIM calculations were performed for compounds 1 and 2, and the selected Bond Critical Points (BCPs) properties were discussed. The extended hydrogen-bond network between the coordinated chromate ions and ammonia ligands acts as reactive redox reaction centres, and both compounds show solid-phase quasi-intramolecular redox reactions with the formation of Co[Co0.5Cr1.5O3.75] and Co[Co0.2Cr1.8O3.90] nanosized regular spinels with nominal Co : Cr = 1 : 1 and 2 : 3 molar ratios, respectively. The tetrahedral positions of these spinels are filled with CoII ions. The octahedral positions of 2 : 3 and 1 : 1 spinels prepared in air are filled CrIII and mainly with CoIII ions. The 2 : 3 spinel prepared under N₂ shows a similar distribution of ions, whereas the 1 : 1 spinel prepared under N₂ contains only CoII ions at T-4, and CrIII, CoIII, and CoII ions at the OC-6 positions, resulting in a strongly defective structure. The position of the chromate ions (inner-sphere coordinated or outer-sphere non-coordinated) plays an important role in the quasi-intramolecular redox reactions and thermal decomposition characteristics of compounds 1 and 2. The inner-sphere coordinated chromate ions of both compounds took part in redox reactions with their own coordinated ammonia only after the loss of the fifth ammonia, in an endothermic ligand-releasing and an exothermic redox reaction mediated by the outer-sphere chromate ion for compounds 1 and 2, respectively. The cobalt(iii) content of both complexes is also reduced completely to cobalt(ii). These spinels were proven to be active catalysts in the visible-light-driven photocatalytic oxidation of rhodamine B with H₂O₂.
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BibTeX
@article{tulik2026reactivity,
title = {{The reactivity of coordinated and uncoordinated chromate ions in the quasi-intramolecular redox reactions of [pentaamminechromatocobalt(iii)] chloride and chromate resulting in tuneable cobalt-chromium spinel oxide catalysts.}},
author = {Bálint Tulik and Zsolt Dürvanger and Shiro Kubuki and Attila Farkas and Stjepko Krehula and Vladimir M Petruševski and Laura Bereczki and Zoltán Homonnay and Milica Marković and Aleksandra Rakic and Dušan Dimić and László Trif and Zoltán Károly and László Kótai and Kende Attila Béres},
journal = {RSC advances},
year = {2026},
month = oct,
doi = {10.1039/d6ra06540f},
url = {https://europepmc.org/article/MED/42921270},
note = {CC BY},
}
RIS
TY - JOUR
TI - The reactivity of coordinated and uncoordinated chromate ions in the quasi-intramolecular redox reactions of [pentaamminechromatocobalt(iii)] chloride and chromate resulting in tuneable cobalt-chromium spinel oxide catalysts.
AU - Bálint Tulik
AU - Zsolt Dürvanger
AU - Shiro Kubuki
AU - Attila Farkas
AU - Stjepko Krehula
AU - Vladimir M Petruševski
AU - Laura Bereczki
AU - Zoltán Homonnay
AU - Milica Marković
AU - Aleksandra Rakic
AU - Dušan Dimić
AU - László Trif
AU - Zoltán Károly
AU - László Kótai
AU - Kende Attila Béres
PY - 2026
DA - 2026/10/23
JO - RSC advances
DO - 10.1039/d6ra06540f
UR - https://europepmc.org/article/MED/42921270
AB - The synthesis routes, crystal and molecular structures, and controlled thermal decomposition reactions of two [pentamminecobalt(iii) compounds having a coordinated chromate ion, [Co(NH₃)₅CrO₄]Cl (compound 1) and [Co(NH₃)₅CrO₄]₂CrO₄ (compound 2) were studied experimentally. Quantum chemical optimizations and QTAIM calculations were performed for compounds 1 and 2, and the selected Bond Critical Points (BCPs) properties were discussed. The extended hydrogen-bond network between the coordinated chromate ions and ammonia ligands acts as reactive redox reaction centres, and both compounds show solid-phase quasi-intramolecular redox reactions with the formation of Co[Co0.5Cr1.5O3.75] and Co[Co0.2Cr1.8O3.90] nanosized regular spinels with nominal Co : Cr = 1 : 1 and 2 : 3 molar ratios, respectively. The tetrahedral positions of these spinels are filled with CoII ions. The octahedral positions of 2 : 3 and 1 : 1 spinels prepared in air are filled CrIII and mainly with CoIII ions. The 2 : 3 spinel prepared under N₂ shows a similar distribution of ions, whereas the 1 : 1 spinel prepared under N₂ contains only CoII ions at T-4, and CrIII, CoIII, and CoII ions at the OC-6 positions, resulting in a strongly defective structure. The position of the chromate ions (inner-sphere coordinated or outer-sphere non-coordinated) plays an important role in the quasi-intramolecular redox reactions and thermal decomposition characteristics of compounds 1 and 2. The inner-sphere coordinated chromate ions of both compounds took part in redox reactions with their own coordinated ammonia only after the loss of the fifth ammonia, in an endothermic ligand-releasing and an exothermic redox reaction mediated by the outer-sphere chromate ion for compounds 1 and 2, respectively. The cobalt(iii) content of both complexes is also reduced completely to cobalt(ii). These spinels were proven to be active catalysts in the visible-light-driven photocatalytic oxidation of rhodamine B with H₂O₂.
SN - 2046-2069
ER -