Book of Abstracts Book of Abstracts - Universität Konstanz

A - 10
112
Planar Boron Clusters and 2D to 3D Transitions
Hua-Jin Zhai, 1,2 A. N. Alexandrova, 3 B. Kiran, 1,2 S. Bulusu, 4 Jun Li, 2 Xiao Cheng Zeng, 3
A. I. Boldyrev, 3 and Lai-Sheng Wang 1
1 Department of Physics, Washington State University, 2710 University Drive, Richland, WA 99352, USA
and
2 W. R. Wiley Environmental Molecular Sciences Laboratory andChemical Science Division, Pacific
Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, USA.
3 Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300, USA
4 Department of Chemistry and Center for Materials Research and Analysis, University of Nebraska-
Lincoln, Lincoln, NE 68588, USA.
One of the most interesting features of elemental boron and many bimetallic boron
compounds is the occurrence of highly symmetric icosahedral clusters. The rich chemistry of
boron is also dominated by three-dimensional (3D) cage structures. We report our recent
investigations of small boron clusters in the size range from 3 to 20 atoms using photoelectron
spectroscopy and ab initio calculations [1-8]. We will present experimental and theoretical
evidence that small boron clusters prefer planar structures and exhibit aromaticity and
antiaromaticity according to the Hückel rules, akin to planar hydrocarbons up to the size of 19
atoms. Aromatic boron clusters possess more circular shapes whereas antiaromatic boron
clusters are elongated, analogous to structural distortions of antiaromatic hydrocarbons. In a
very recent study [8], we show that 3D structures begin at B20, which has a double ring global
minimum structure. The 2D to 3D structural transition observed at B20 suggests that it may be
considered as the embryo of the thinnest single-wall boron nanotubes.
References
B12 B13 B20
[1] H. J. Zhai, L. S. Wang, A. N. Alexandrova, and A. I. Boldyrev, J. Chem. Phys. 117, 7917-7924
(2002).
[2] A. N. Alexandrova, A. I. Boldyrev, H. J. Zhai, L. S. Wang, E. Steiner, and P. W. Fowler, J. Phys.
Chem. A 107, 1359-1369 (2003).
[3] H. J. Zhai, A. N. Alexandrova, K. A. Birch, A. I. Boldyrev, and L. S. Wang, Angew. Chem. Int. Ed.
42, 6004-6008 (2003).
[4] H. J. Zhai, B. Kiran, J. Li, and L. S. Wang, Nature Materials 2, 827-833 (2003).
[5] H. J. Zhai, L. S. Wang, A. N. Alexandrova, A. I. Boldyrev, and V. G. Zakrzewski, J. Phys. Chem.
A 107, 9319-9328 (2003)
[6] A. N. Alexandrova, A. I Boldyrev, H. J. Zhai, and L. S. Wang, J. Phys. Chem. A 108, 3509-3517
(2004).
[7] “Boron Flat Out” (S. K. Ritter), Chem. & Eng. News 82 (9), 28-32 (March 1 (2004).
[8] B. Kiran, S. Bulusu, H. J. Zhai, S. Yoo, X. C. Zeng, and L. S. Wang, Proc. Natl. Acad. Sci. (USA),
in press.