
%0 Journal Article
%A Craig, DC 
%A Paddonrow, MN 
%A Patney, HK 
%T The Syntheses and Crystal-Structures of Decahydro-5,14:6,13:7,12-Trimethanopentacene and Decahydro-5,14-7,12-Dimethanopentacene: Two Useful Molecules for Investigating Laticyclic Hyperconjugation
%J Australian Journal of Chemistry
%D 1986/10/01
%V 39
%N 10
%P 1587-1608
%K 
%R https://doi.org/10.1071/CH9861587
%U https://www.publish.csiro.au/paper/CH9861587 
%X The syntheses of decahydro-5,14:6,13:7,12-trimethanopentacene and decahydro-5,14:7,12-dimethanopentacene are described (see Schemes 1 and 2 respectively). Diels -Alder reaction of diene (10) with two equivalents of tetrachlorothiophen 1,1-dioxide (11) gave the adduct (12), which was aromatized to (13) through treatment with base. Reductive dechlorination (Na/ PriOH ) of (13) gave (6). A similar set of reactions performed on (17), itself prepared from cyclohexa-1,4-diene and two equivalents of hexachlorocyclopentadiene (15), gave (7). The crystal structures of (6) and (7) were determined. An interesting feature of the structure of (7) is the slight endo pyramidalization (by c. 3&#176;) of the trigonal carbon atoms C 4a, C 7a, C 11a and C 14a. Model ab initio calculations (STO-3G basis set) on complexes (27) and (28), whose geometries were culled from the crystal structure of (6), indicate that significant laticyclic hyperconjugative interactions (c. 0.3 eV ) are mainly responsible for causing the observed splitting between the &#960;s+&#960;s and &#960;s-&#960;s levels in the photoelectron spectrum of (6). Orbital interactions through the pair of six connecting sigma bonds (OIT-6-B) in (6) have a negligible effect (c. 0.08 eV ) on these levels. In agreement with prediction, laticyclic  hyperconjugation does not affect the &#960;a+&#960;a and &#960;a-&#960;a levels. 
