Theoretical Study on the Mechanism of Reaction of Ground-State Fe Atoms with Carbon Dioxide

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Title:Theoretical Study on the Mechanism of Reaction of Ground-State Fe Atoms with Carbon Dioxide
Creators:
Pantazis, Dimitrios A.
Tsipis, Athanassios C.
Tsipis, Constantinos A.
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 69, 1, pp. 13-33
Uncontrolled Keywords:<i>Ab initio</i> calculations, FeCO<sub>2</sub> complexes, Reaction mechanism, Iron, Electronic structure, CO<sub>2</sub>-to-CO reduction, DFT

Abstract

Density functional calculations at the B3LYP level of theory, using the 6-31G(d) and 6-311+G(3df) basis sets, provide a satisfactory description of the geometric and energetic reaction profile of the Fe + CO<sub>2</sub> → FeO + CO reaction. The reaction is predicted to be endothermic by 23.24 kcal/mol at the B3LYP/6-311+G(3df)//B3LYP/6-31G(d) level of theory and to proceed by formation of either a Fe(η<sup>2</sup>-<strong>OC</strong>O) or a Fe(η<sup>3</sup>-<strong>OCO</strong>) intermediate. The Fe(η<sup>2</sup>-<strong>OC</strong>O) intermediate in the <sup>5</sup>A' ground state is weakly bound with respect to Fe(<sup>5</sup>D) and CO<sub>2</sub> dissociation products by 0.78 (2.88) kcal/mol at the B3LYP/6-31G(d) (B3LYP/6-311+ G(3df)//B3LYP/6-31G(d)) levels of theory. In contrast, the Fe(η<sup>3</sup>-<strong>OCO</strong>) intermediate in the <sup>5</sup>A<sub>1</sub> ground state is unbound with respect to Fe(<sup>5</sup>D) and CO<sub>2</sub> dissociation products by 8.27 (11.15) kcal/mol at the same levels of theory. However, both intermediates are strongly bound relative to the separated Fe<sup>+</sup>(<sup>6</sup>D) and [CO<sub>2</sub>]<sup>-</sup> anion; the computed bond dissociation energies for the Fe(η<sup>2</sup>-<strong>OC</strong>O) and Fe(η<sup>3</sup>-<strong>OCO</strong>) intermediates are 207.33 and 198.28 kcal/mol in terms of ∆<i>E</i><sub>0</sub> at the B3LYP/6-31G(d), respectively. In the Fe(η<sup>2</sup>-<strong>OC</strong>O) and Fe(η<sup>3</sup>-<strong>OCO</strong>) intermediates, an intramolecular insertion reaction of the Fe atom to O-C bond takes place yielding the isomeric OFe(η<sup>1</sup>-<strong>C</strong>O) and OFe(η<sup>1</sup>-<strong>O</strong>C) products, respectively, with a relatively low activation barrier of 25.24 (21.69) and 26.36 (23.38) kcal/mol at the B3LYP/6-31G(d) (B3LYP/6-311+G(3df)//B3LYP/6-31G(d)) levels of theory, respectively. The calculated structures, relative stability and bonding properties of all stationary points are discussed with respect to computed electronic and spectroscopic properties, such as charge density distribution and harmonic vibrational frequencies. <p>

Title:Theoretical Study on the Mechanism of Reaction of Ground-State Fe Atoms with Carbon Dioxide
Creators:
Pantazis, Dimitrios A.
Tsipis, Athanassios C.
Tsipis, Constantinos A.
Uncontrolled Keywords:<i>Ab initio</i> calculations, FeCO<sub>2</sub> complexes, Reaction mechanism, Iron, Electronic structure, CO<sub>2</sub>-to-CO reduction, DFT
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:69
Number:1
Page Range:pp. 13-33
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc20040013UNSPECIFIED
ID Code:2193
Item Type:Article
Deposited On:06 Feb 2009 17:16
Last Modified:06 Feb 2009 16:16

Citation

Pantazis, Dimitrios A.; Tsipis, Athanassios C.; Tsipis, Constantinos A. (2004) Theoretical Study on the Mechanism of Reaction of Ground-State Fe Atoms with Carbon Dioxide. Collection of Czechoslovak Chemical Communications, 69 (1). pp. 13-33. ISSN 0010-0765

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