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Published on: August 12, 2019
Unsaturation in binuclear cyclopentadienyliron carbonyls
Hongyan Wang1, Yaoming Xie, R Bruce King
1Atomic and Molecular Physics Institute, Sichuan University, Chengdu 610065, People's Republic of China.
Inorganic Chemistry
|April 11, 2006
Summary
Density functional theory (DFT) investigated binuclear cyclopentadienyliron carbonyls (Cp2Fe2(CO)n). DFT predicts stable isomers for Cp2Fe2(CO)4 and identifies lowest-energy structures for unsaturated Cp2Fe2(CO)3, Cp2Fe2(CO)2, and Cp2Fe2(CO) with varying iron-iron bond orders.
Area of Science:
- Organometallic Chemistry
- Computational Chemistry
- Inorganic Chemistry
Background:
- Binuclear cyclopentadienyliron carbonyls (Cp2Fe2(CO)n) are a class of organometallic compounds with diverse structures and bonding.
- Understanding their stability and electronic configurations is crucial for predicting reactivity and potential applications.
- Previous experimental studies have identified several isomers, but theoretical investigations are needed for detailed structural and energetic analysis.
Purpose of the Study:
- To investigate the structures and energies of binuclear cyclopentadienyliron carbonyls (Cp2Fe2(CO)n, n = 4, 3, 2, 1) using computational methods.
- To determine the global minimum energy structures for various degrees of carbonyl unsaturation.
- To elucidate the nature of iron-iron bonding in these complexes.
Main Methods:
- Density Functional Theory (DFT) calculations were employed.
- The B3LYP and BP86 functionals were utilized for electronic structure calculations.
- Vibrational frequency analysis was performed to confirm genuine minima.
Main Results:
- DFT accurately predicted the experimentally observed trans- and cis-isomers of Cp2Fe2(CO)4, indicating a facile equilibrium between them.
- For Cp2Fe2(CO)3, the triplet isomer with an Fe=Fe double bond was identified as the global minimum.
- The lowest-energy structure for Cp2Fe2(CO)2 featured a dibridged configuration with a short Fe-Fe distance, suggesting an Fe[triple bond]Fe triple bond.
- Cp2Fe2(CO) exhibited a triplet unsymmetrically bridged structure with a short Fe-Fe distance, indicative of an Fe[quadruple bond]Fe quadruple bond.
Conclusions:
- DFT provides reliable predictions for the structures and energies of binuclear cyclopentadienyliron carbonyls.
- The study reveals a trend of increasing iron-iron bond order with decreasing carbonyl ligands, from double bonds in Cp2Fe2(CO)3 to quadruple bonds in Cp2Fe2(CO).
- These findings contribute to a deeper understanding of bonding and electronic properties in iron-containing clusters.
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