Planar Hexacoordinate Carbon: A Viable Possibility
Kai Exner,
Paul von Ragué Schleyer*
The viability of molecules with planar hexacoordinate
carbon atoms is demonstrated by density-functional theory (DFT)
calculations for CB62-, a
CB6H2 isomer, and three
C3B4 minima. All of these species have six
electrons and are aromatic. Although other C3B4
isomers are lower in energy, the activation barriers for the
rearrangements of the three planar carbon C3B4
minima into more stable isomers are appreciable, and experimental
observation should be possible. High-level ab initio calculations
confirm the DFT results. The planar hexacoordination in these species
does not violate the octet rule because six partial bonds to the
central carbons are involved.
Center for Computational Quantum Chemistry, Computational
Chemistry Annex, University of Georgia, Athens, GA 30602-2525, USA.
*
To whom correspondence should be addressed. E-mail:
schleyer{at}chem.uga.edu