Modeling structures and vibrational frequencies for dinitrosyl iron complexes (DNICs) with density functional theory
Scott M Brothers1, Marcetta Y Darensbourg, Michael B Hall
1Department of Chemistry, Texas A&M University, College Station, Texas 77840, USA.
Inorganic Chemistry
|August 9, 2011
Summary
Researchers developed a computational method to accurately calculate vibrational frequencies of dinitrosyl iron complexes (DNICs), crucial for understanding biological nitric oxide (NO) storage and transport. This method aids in studying DNICs involved in NO signaling and vasodilation.
Area of Science:
- Computational Chemistry
- Biochemistry
- Spectroscopy
Background:
- Nitric oxide (NO) is vital for biological signaling and vasodilation.
- Dinitrosyl iron complexes (DNICs) are implicated in biological NO storage and transport.
- Spectroscopic features, particularly NO vibrational frequencies, are sensitive indicators of DNIC structure and electronic state.
Purpose of the Study:
- To develop and validate a computational methodology for accurately calculating NO vibrational frequencies in DNICs.
- To assess the influence of functionals and basis sets on calculated vibrational frequencies.
- To investigate the ground state energetics, geometric parameters, and vibrational frequencies of various diiron trinitrosyl complexes.
Main Methods:
- Systematic examination of various density functional theory (DFT) functionals and basis sets.
- Calibration of computational methods using three model complexes: (L)(CO)Fe(NO)(2).
- Application of the validated method to calculate properties of sulfur-bridged diiron trinitrosyl complexes.
Main Results:
- The BP86 functional with SDD/ECP and 6-311++G(d,p) basis sets accurately predicted experimental vibrational frequencies (±40 cm(-1)).
- Calculations for sulfur-bridged diiron trinitrosyl complexes showed good correlation with experimental data.
- A stable triplet ground state was optimized for [Fe(NO)(2){Fe(NS(3))(NO)}-μ-S,S'], contrasting with previous studies.
Conclusions:
- The developed computational approach provides a reliable tool for studying DNICs and their biological roles.
- The findings enhance understanding of NO storage and transport mechanisms mediated by iron-sulfur complexes.
- Accurate computational modeling is crucial for interpreting spectroscopic data and predicting the behavior of metalloorganic compounds.
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