Understanding the role of fluorination in the mechanistic nature of the water splitting process catalyzed by cobalt tris-(2-pyridylmethyl)amine complexes

Gorantla, Koteswara Rao and Mallik, Bhabani S. (2021) Understanding the role of fluorination in the mechanistic nature of the water splitting process catalyzed by cobalt tris-(2-pyridylmethyl)amine complexes. Sustainable Energy & Fuels, 5 (8). pp. 2313-2324. ISSN 2398-4902

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Abstract

We report the reaction mechanism of the oxygen evolution reaction catalyzed by penta-coordinated [(CoV(TPA-αF3)(O))]3+(TPA = tris-(2-pyridylmethyl)amine) and hexa-coordinated [CoV(TPA-αF3)(O)OH]2+cobalt complexes for the formation of the oxygen-oxygen bond and the role of fluorination with the help of density functional theory. The nature of the orbitals involved in the formation of the oxygen-oxygen bond by these complexes is examined. The formation of the oxygen-oxygen bond occurs by the interaction of the dx2−y2* orbital of metal with the σ*-orbital of the hydroxide in the case of [(CoV(TPA-αF3)(O)OH]2+, while, in the case of [(CoV(TPA-αF3)(O))]3+, the dz2*-orbital accepted the electron from the hydroxide. The activation barrier for the oxygen-oxygen bond formation by the penta coordinated complex is lower than that of the hexa-coordinated complex. The release of oxygen through both the catalytic processes has nearly equal activation free energies. From the spin density analysis, we observe that the oxo-complexes are stabilized by sharing the spin density on the nitrogen atoms with fluorine atoms of the modified TPA ligand. Comparing the four-proton and four-electron process of the catalytic cycle with both catalytic species, it is found that the penta-coordinated complex ([(CoV(TPA-αF3)(O))]3+) requires a lower activation free energy barrier than the hexa-coordinated complex [CoV(TPA-αF3)(O)OH]2.

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IITH Creators:

IITH Creators	ORCiD
Gorantla, Koteswara Rao	UNSPECIFIED
Mallik, Bhabani Shankar	http://orcid.org/0000-0001-9657-1497

Item Type:

Article

Uncontrolled Keywords:

Activation barriers; Activation free energy; Catalytic cycles; Catalytic process; Catalytic species; Coordinated complexes; Four-electron process; Reaction mechanism;Activation energy; Catalysis; Chemical bonds; Coordination reactions; Density functional theory; Fluorination; Free energy; Halogenation

Subjects:

Chemistry

Divisions:

Department of Chemistry

Depositing User:

. LibTrainee 2021

Date Deposited:

30 Jun 2021 06:27

Last Modified:

11 Mar 2022 05:50

URI:

http://raiithold.iith.ac.in/id/eprint/8054