ORGN 239 |
Clar valence bond representation of π-bonding in carbon nanotubes
| Jason L. Ormsby and Benjamin T. King. Department of Chemistry, University of Nevada, Reno, NV 89557 |
| The application of the Clar aromatic sextet valence bond (VB) model to carbon nanotubes (CNTs) with roll-up vectors (m,n) provides a real-space model of their electronic structure. If (m - n) = 3k, where k is an integer, then all π electrons can be represented by aromatic sextets, and the CNT is fully benzenoid. This criterion is known to be necessary for conductivity in CNTs, and therefore only fully benzenoid CNTs are metallic. This behavior contrasts with finite planar polycyclic aromatic hydrocarbons, in which the fully benzenoid structures have large HOMO-LUMO gaps. For CNTs that are not fully benzenoid, e.g. (m - n) = 3k + l where l = 1 or 2 and k is an integer, a seam of double bonds wraps about an otherwise benzenoid CNT. Nucleus independent chemical shift calculations of CNT segments support the Clar VB picture. |
| |
|
Physical Organic Chemistry: Calculations, Mechanisms, Photochemistry, and High-Energy Species
8:00 AM-12:00 PM, Tuesday, March 30, 2004 Anaheim Convention Center -- 303A, Oral
Division of Organic Chemistry
The 227th ACS National Meeting, Anaheim, CA, March 28-April 1, 2004
|