IISER Tirupati researchers have made significant strides in understanding the nitric oxide oxidation (NOO) reactions of cobalt-peroxo and cobalt-nitrosyl complexes. Their findings have been published in the journal Inorganic Chemistry.
Outcomes:
- IISER Tirupati researchers prepared and characterized two new cobalt complexes
- The NOO reactions of the complexes were studied and characterized by various spectroscopic measurements and DFT-optimized structures
- Both NOO reactions proceed via a presumed peroxynitrite intermediate
- Mechanistic investigation using 2,4-di-tert-butylphenol indirectly suggests the formation of a peroxynitrite intermediate
- Tracking the source of the N-atom in the NOO reactions using 15N-labeled nitrogen revealed the origin of the N-atoms in the final products
The researchers at IISER Tirupati prepared and characterized two new cobalt complexes – [(HMTETA)CoIII(O22–)]+ (2, S = 2) and [(HMTETA)Co(NO)]2+ (3, S = 1) – from [(HMTETA)CoII(CH3CN)2]2+ (1). Both complexes were characterized by various spectroscopic measurements, including their DFT-optimized structures.
In the presence of nitric oxide (NO), complex 2 produced the cobalt-nitrato [(HMTETA)CoII(NO3–)]+ (CoII–NO3–, 4) complex. In contrast, when complex 3 reacted with a superoxide (O2•–) anion, it generated the cobalt-nitrito [(HMTETA)CoII(NO2–)]+ (CoII–NO2–, 5) complex with O2 evolution. Experiments performed using 18/16O-labeled superoxide (18O2•–/16O2•–) showed that O2 originated from the O2•– anion.
Both NOO reactions are believed to proceed via a presumed peroxynitrite (PN) intermediate. Although the researchers did not obtain direct spectral evidence for the proposed PN species, the mechanistic investigation using 2,4-di-tert-butylphenol indirectly suggests the formation of a PN intermediate.
Furthermore, tracking the source of the N-atom in the above NOO reactions using 15N-labeled nitrogen (15NO) revealed that the N-atoms in 4 (CoII–15NO3–) and 5 (CoII–15NO2–) were derived from the 15NO moiety.
In conclusion, the study sheds new light on the NOO reactions of cobalt-peroxo and cobalt-nitrosyl complexes and could have significant implications in the field of inorganic chemistry.
Nitric Oxide Oxygenation Reactions of Cobalt-Peroxo and Cobalt- Nitrosyl Complexes
Kulbir; Keerthi; Beegam; Das; Bhardwaj; Ansari; Singh; Kumar
Full-text link: https://doi.org/10.1021/acs.inorgchem.3c00639
What this paper is about
- In this regard, different reaction systems have been explored, i.e., NO oxidation reactions via metaloxygen adducts, 10 and/or Karlin and co-workers showed the formation of NOD product in the reaction of NO with heme-superoxide.
- Additionally to the above experimental characterization, the electronic structure of 2 was determined by DFT calculations, suggesting a distorted octahedral geometry with an S = 2 ground state 1 for the 5 2 hs.
- Solution FT-IR spectrum of 1 + NO showed a peak at 1715 cm 1 suggesting a. CoNO} 8, as reported in our previous reports.
What you can learn
- CoNO} reported by Nam and co-workers, 11 the NOO reaction was found to be independent of the spin state of the Co-center.
- Furthermore, IISER Tirupati researchers treated 5 with NO under Ar and followed the reaction with UVvis measurements, showing the formation of. This reaction confirms that the 5 has the ionizable/ solvable NO These reactions are believed to be regulated by the mode of the coordinating of PN in the [M-PN] + intermediates.
- Experimental details, crystallographic data, single-crystal X-ray diffraction structures and their parameters, 1 H NMR of all compounds, ESI-mass spectra, additional FI-IR data, UVvis absorption spectra, kinetics of reactivity, computed Eigen-value plot, and B3LYP/D2 optimized Cartesian coordinates.
Core Q&A related to this research
What is the focus of the paper “Nitric Oxide Oxygenation Reactions of Cobalt-Peroxo and Cobalt- Nitrosyl Complexes”?
The paper focuses on a comparative study of the nitric oxide oxidation reactions of CoIII-peroxo and Co-nitrosyl complexes.
How many complexes were prepared and characterized by IISER Tirupati researchers in this study?
IISER Tirupati researchers prepared and characterized two complexes: [(HMTETA)CoIII(O22–)]+ and [(HMTETA)Co(NO)]2+.
What is the difference in the spin states of the two complexes prepared by IISER Tirupati researchers?
The spin state of the CoIII-peroxo complex is S = 2, while the spin state of the Co-nitrosyl complex is S = 1.
What is the reaction product of complex 2 in the presence of NO?
Complex 2 produces CoII-nitrato [(HMTETA)CoII(NO3–)]+ complex in the presence of NO.
What is the reaction product of complex 3 with a superoxide anion?
Complex 3 generates CoII-nitrito [(HMTETA)CoII(NO2–)]+ with O2 evolution when it reacts with a superoxide anion.
How did the researchers track the source of the N-atom in the NOO reactions?
The researchers tracked the source of the N-atom in the NOO reactions using 15N-labeled nitrogen (15NO).
What do the NOO reactions believed to proceed via a presumed peroxynitrite (PN) intermediate?
Both the NOO reactions are believed to proceed via a presumed peroxynitrite (PN) intermediate.
Basic Q&A related to this research
What is Nitric oxide oxidation?
Answer: Nitric oxide oxidation (NOO) is a chemical reaction where nitric oxide (NO) reacts with other chemical species, resulting in the oxidation of NO to other products.
What are Cobalt-Peroxo complexes?
Answer: Cobalt-Peroxo complexes are chemical compounds that contain a cobalt ion coordinated with a peroxide (O22-) ligand.
What are Cobalt- Nitrosyl complexes?
Answer: Cobalt-Nitrosyl complexes are chemical compounds that contain a cobalt ion coordinated with a nitric oxide (NO) ligand.
What is N4-donor ligand?
Answer: N4-donor ligand is a type of ligand that has four nitrogen atoms in its structure, which can donate lone pair electrons to form coordination bonds with metal ions.
What are spectroscopic measurements?
Answer: Spectroscopic measurements are techniques that use light to study the properties of matter, such as its absorption, emission, and scattering.
What are DFT-optimized structures?
Answer: DFT-optimized structures refer to the optimized geometry of a molecule or a complex calculated using Density Functional Theory (DFT), a computational method used to study the electronic structure of molecules and materials.
What is CoII-nitrato?
Answer: CoII-nitrato is a chemical compound that contains a cobalt ion coordinated with a nitrate (NO3-) ligand in a +2 oxidation state.
What is CoII-nitrito?
Answer: CoII-nitrito is a chemical compound that contains a cobalt ion coordinated with a nitrite (NO2-) ligand in a +2 oxidation state.
What is peroxynitrite?
Answer: Peroxynitrite is a reactive nitrogen species that can be formed from the reaction of nitric oxide (NO) and superoxide (O2•-) radicals, and is involved in various biological and pathological processes.
What is 15N-labeled nitrogen?
Answer: 15N-labeled nitrogen is a nitrogen isotope that contains an extra neutron in its nucleus, which can be used as a tracer to study the fate and distribution of nitrogen atoms in chemical reactions and biological systems.
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