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Electronic structure and bonding of {Fe(PhNO2)}6 complexes: a density functional theory study
Olexandr Isayev1, Leonid Gorb, Igor Zilberberg
1Computational Center for Molecular Structure and Interactions, Jackson State University, Jackson, MS 39217, USA.
The Journal of Physical Chemistry. A
|April 20, 2007
Summary
Density functional theory quantifies electron transfer in nitro-aromatic compound (NAC) reduction by iron compounds. This reveals bonding structures crucial for understanding NAC degradation mechanisms.
Area of Science:
- Computational Chemistry
- Environmental Chemistry
- Materials Science
Background:
- Nitro-aromatic compounds (NACs) are environmental pollutants degraded via reduction.
- Electron transfer from reductants to NACs is a key step in their degradation.
- Understanding the extent of electron transfer is vital for assessing reductant activity.
Purpose of the Study:
- To estimate the electron transfer extent during NAC reduction by model ferrous-containing reductants.
- To analyze the activity of various Fe(II) hydroxides in degrading nitrobenzene.
- To elucidate the electronic structure and bonding in model nitrobenzene-iron complexes.
Main Methods:
- Application of unrestricted density functional theory (DFT) using paired Löwdin-Amos-Hall orbitals.
- Modeling of nitrobenzene (NB) complexes with cationic [FeOH]+, neutral Fe(OH)2, and anionic [Fe(OH)3]-.
- Analysis of spin contamination to identify electron transfer processes and localized orbitals.
Main Results:
- DFT calculations reveal spin contamination indicative of electron transfer during reduction.
- Orbital analysis quantifies electron transfer states and characterizes bonding as covalent or charge-transfer.
- The electronic structure of the {Fe(PhNO2)} unit is described by covalent [Fe+2-PhNO2] or charge-transfer [Fe+3-{PhNO2}-] configurations.
Conclusions:
- The study provides a computational method to estimate electron transfer in NAC reduction.
- Insights into the electronic structure of iron-nitrobenzene complexes aid in understanding degradation pathways.
- The findings are applicable to designing effective reductants for NAC remediation.
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