No abstract

No abstract

Valency-bond calculations on heptalene suggest that bond length alternation occurs in the ground state. Penney-Dirac bond orders have been determined.Recently a successful synthesis of the unsaturated hydrocarbon heptalene C12Hlo ( fig. 1) has been performed by Dauben and Berfelliz. From the rather limited experimental data these authors concluded that the compound more closely resembles a weakly interacting cyclopolyene than a strongly interacting aromatic system. Such behaviour may be supported by calculations based on the molecular orbital approximation 3, 4 9 5 . ( b) Fig. 1.