Collect. Czech. Chem. Commun. 2008, 73, 1525-1551

Coupled Cluster Study of Polycyclopentanes: Structure and Properties of C5H2n, n = 0-4

Libor Veisa, Petr Čárskya, Jiří Pittnera and Josef Michlb,a,*

a J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v. v. i., Dolejškova 3, 182 23 Prague 8, Czech Republic
b Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, U.S.A.


The title hydrocarbons have been examined by the CCSD(T)/cc-pVTZ (singlets) and UMP2/cc-pVTZ (triplets) methods. They were confirmed to represent local minima on the singlet potential energy surface, while 1,3-biradical, 1,4-biradical, or carbene structures were found on the triplet surface, including an intermediate for the triplet energy transfer from one to the other double bond of 1,4-pentadiene. Bonding is discussed in terms of Weinhold's NBO theory and the absence of a simple correlation between bond strength and bond length in these highly strained systems is pointed out. Predictions of NMR, IR, and Raman spectra are provided.

Keywords: Ab initio calculations; Polycyclopentanes; Single-reference and multireference coupled clusters; NBO analysis; Predicted NMR spectra; Predicted IR and Raman spectra.

References: 56 live references.