Helices of Boron−Nitrogen Hexagons and Decagons. A Theoretical Study

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 112; no. 29; pp. 6783 - 6787
• Main Authors: Szakacs, Csaba E, Mezey, Paul G
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 24.07.2008
• Subjects: A: Molecular Structure, Quantum Chemistry, General Theory
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp802722p

Ab initio self-consistent field molecular orbital and density functional theory calculations have been performed on a series of helical boron−nitrogen structures comprised of fused hexagons and larger polygons. The presence of an even number N of rings in the boron−nitrogen [N]helicenes leads to the possibility of angular isomers. The electronic structure and stability of three isomeric nonhydrogenated boron−nitrogen helices were investigated at the HF/6-31G(d) and the B3LYP/6-31G(d) levels of theory. According to this study some of the initially assumed regular helical structures are unstable; two types of the isomeric structures convert to characteristically different equilibrium geometries. Electron density contours were calculated in order to interpret the existing bonding patterns.