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Cyclic boron clusters enclosing planar hypercoordinate cobalt, iron, and nickel
Keigo Ito1, Zhifeng Pu, Qian-Shu Li
1Department of Chemistry, Center for Computational Chemistry, University of Georgia, Athens, Georgia 30602, USA.
Inorganic Chemistry
|October 31, 2008
Summary
Stable planar cyclic boron clusters featuring cobalt, iron, and nickel were discovered. These novel structures exhibit unique electronic properties, suggesting potential for future gas-phase research.
Area of Science:
- Computational Chemistry
- Materials Science
- Inorganic Chemistry
Background:
- Exploration of novel boron clusters is crucial for advancing materials science.
- Understanding the electronic structure and stability of metal-boron compounds is an ongoing challenge.
- Planar hypercoordinate structures offer unique chemical bonding and electronic properties.
Purpose of the Study:
- To computationally investigate the stability and electronic characteristics of planar cyclic boron clusters containing transition metals (cobalt, iron, nickel).
- To identify global minima structures for these metal-boron clusters using density functional theory.
- To analyze the aromaticity and electronic delocalization within these novel cluster systems.
Main Methods:
- Density Functional Theory (DFT) calculations using the BP86/TZVPP and PW91/TZVPP levels of theory.
- Stochastic searches were employed to explore singlet and triplet potential energy surfaces.
- Nuclear Independent Chemical Shift (NICS) and CMO-NICS analyses were performed to assess aromaticity.
Main Results:
- Singlet D(8h) CoB(8)(-) and D(9h) FeB(9)(-) were identified as stable global minima, exhibiting planar hypercoordinate structures.
- These anions display a double aromatic character, with 6 pi and 10 radial electrons, confirmed by NICS analyses.
- Isoelectronic CoB(9) and NiB(9)(+) favor nonplanar structures, unlike their anionic counterparts.
Conclusions:
- The study confirms the stability of novel planar cyclic boron clusters with transition metals, CoB(8)(-) and FeB(9)(-).
- These anionic clusters possess significant aromaticity, making them intriguing candidates for experimental investigation.
- The findings highlight the diverse structural preferences of isoelectronic metal-boron systems based on charge and metal identity.
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