Related Experiment Video
Updated: May 28, 2026
08:44
Measurements of Long-range Electronic Correlations During Femtosecond Diffraction Experiments Performed on Nanocrystals of Buckminsterfullerene
Published on: August 22, 2017
Ring currents in boron and carbon buckyballs, B80 and C60
David E Bean1, Jules Tshishimbi Muya, Patrick W Fowler
1Department of Chemistry, University of Sheffield, Sheffield, S3 7HF, UK.
Physical Chemistry Chemical Physics : PCCP
|October 19, 2011
Summary
Boron buckyballs (B(80)) exhibit strong paratropic ring currents, suggesting weak anti-aromaticity. This finding, similar to carbon buckyballs but with higher density, offers new insights into boron cage aromaticity.
Area of Science:
- Computational Chemistry
- Materials Science
- Quantum Chemistry
Background:
- Understanding the electronic properties and aromaticity of novel fullerene-like structures is crucial for materials science.
- Boron buckyballs, such as B(80), present unique structural and electronic characteristics compared to their carbon counterparts.
- Aromaticity in boron cages is a complex topic, with experimental and theoretical evidence often debated.
Purpose of the Study:
- To investigate the magnetically induced ring currents in the boron buckyball B(80) using the ipsocentric method.
- To compare the electronic current patterns of B(80) with those of carbon buckyballs.
- To determine the aromatic or anti-aromatic nature of B(80) based on calculated ring currents and NICS values.
Main Methods:
- Employed the ipsocentric method at the coupled Hartree-Fock (CHF) level of theory.
- Calculated magnetically induced ring currents for both the highly symmetric I(h) and distorted T(h) geometries of B(80).
- Analyzed current densities, patterns, and Nuclear Independent Chemical Shielding (NICS) values.
Main Results:
- Observed a close similarity in current patterns between boron and carbon buckyballs, with B(80) displaying higher current density.
- Identified predominant paratropic currents on the pentagonal faces of B(80).
- Calculated a positive central NICS value for B(80), indicating a deviation from aromaticity.
Conclusions:
- The electronic current distribution and positive NICS value strongly suggest that B(80) is weakly anti-aromatic.
- The findings provide theoretical support for classifying B(80) as an anti-aromatic system.
- Largest orbital contributions to ring currents were identified, linked to frontier orbital excitations, offering deeper electronic structure insights.
Related Concept Videos
03:24Hybridization of Atomic Orbitals I
The mathematical expression known as the wave function, ψ, contains information about each orbital and the wavelike properties of electrons in an isolated atom. When atoms are bound together in a molecule, the wave functions combine to produce new mathematical descriptions that have different shapes. This process of combining the wave functions for atomic orbitals is called hybridization and is mathematically accomplished by the linear combination of atomic orbitals. The new orbitals that...
01:18Structure of Benzene: Molecular Orbital Model
According to the molecular orbital (MO) model, benzene has a planar structure with a regular hexagon of six sp2 hybridized carbons. As shown in Figure 1, each carbon is bonded to three other atoms with C–C–C and H–C–C bond angles of 120°. The C–H bond length is 109 pm, and the C–C bond length is 139 pm which is midway between the single bond length of sp3 hybridized carbons (154 pm) and sp2 hybridized carbons (133 pm).
02:11Conformations of Cyclohexane
Cyclohexane does not exist in a planar form due to the high angle and torsional strain it would experience in the planar structure. Instead, it adopts non-planar chair and boat conformations.
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal tetrahedral value,...
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal tetrahedral value,...
02:02Chair Conformation of Cyclohexane
The chair conformation is the most stable form of cyclohexane due to the absence of angle and torsional strain. The absence of angle strain is a result of cyclohexane’s bond angle being very close to the ideal tetrahedral bond angle of 109.5° in its chair conformer. Similarly, the torsional strain is also absent owing to the perfectly staggered arrangement of bonds.
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this staggered...
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this staggered...
01:14π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds
In aromatic compounds, such as benzene, the circulation of (4n + 2) π-electrons sets up a diamagnetic or diatropic ring current around the perimeter of the molecule. This current induces a magnetic field that opposes the external field inside the ring and reinforces it on the outside. The protons in benzene are deshielded and exhibit high chemical shifts in the range 6.5–8.5 ppm. The shielding effect at the center of the ring is evident in complex aromatic molecules, such as annulenes. In...
01:18Frost Circles for Different Conjugated Systems
The inscribed polygon method is consistent with Hückel’s 4n + 2 rule and helps to learn whether the given cyclic compound is aromatic or not. The compound is stable and aromatic if every bonding molecular orbital (MO) is completely filled with a pair of electrons. However, if the non-bonding or antibonding orbitals are filled with electrons, the compound is unstable and not aromatic. Consider the Frost circle diagrams for cycloalkenes containing 4 to 8 carbons.