Low-Lying Isomers of the B9- Boron Cluster: The Planar Molecular Wheel Versus Three-Dimensional Structures

Journal Article · Mon Jul 14 04:00:00 UTC 2008 · Journal of Chemical Physics, 129(2):187-193. Article number: 024302

DOI:https://doi.org/10.1063/1.2948405· OSTI ID:943398

Pan, Li-Li; Li, Jun; Wang, Lai S

The B9- cluster was found previously to be an unprecedented molecular wheel containing an octacoordinate planar boron with D8h symmetry in a combined photoelectron spectroscopy (PES) and theoretical study [H. J. Zhai et al., Angew. Chem. Int. Ed. 42, 6004 (2003)]. However, the PES spectra of B9- exhibit minor features that cannot be explained by the global minimum D8h structure, suggesting possible contributions from low-lying isomers at finite temperatures. Here we present Car-Parrinello molecular dynamics with simulated annealing simulations to fully explore the potential energy surface of B9- and search for low-lying isomers that may account for the minor PES features. We performed density functional theory (DFT) calculations with different exchange-correlation functionals and ab initio calculations at various levels of theory with different basis sets. Two three-dimensional low-lying isomers were found, both of Cs symmetry, 6.29 (Cs-2) and 10.23 (Cs-1) kcal/mol higher in energy than the D8h structure at the highest CCSD(T) level of theory. Calculated detachment transitions from the Cs-2 isomer are in excellent agreement with the minor features observed in the PES spectra of B9-. The B9- cluster proves to be a challenge for most DFT methods and the calculated relative energies strongly depend on the exchange-correlation functionals, providing an excellent example for evaluating the accuracies of various DFT methods.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 943398
• Report Number(s): PNNL-SA-61069; 25394; KP1504020
• Journal Information: Journal of Chemical Physics, 129(2):187-193. Article number: 024302, Journal Name: Journal of Chemical Physics, 129(2):187-193. Article number: 024302 Journal Issue: 2 Vol. 129; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
BORON
DENSITY FUNCTIONAL METHOD
Environmental Molecular Sciences Laboratory
ISOMERS
MOLECULAR CLUSTERS
PHOTOELECTRON SPECTROSCOPY
POTENTIAL ENERGY