A computational study of sulfur bridged cyclooctatetraenophanes

Calculations of several thiacyclooctatetraenophanes predicted, as part of their overall geometry, substantial flattening of the cyclooctatetraene (COT) structures relative to the tub conformation generally associated with the COT molecule. The COT structures were approximately parallel to each other and the interplanar distances were predicted to be within 2.787-2.803 angstrom at the DFT/UB3YLP level of calculation. DFT/UB3LYP optimized geometries afforded significant delocalization of the COT structures in each of the thiacyclooctatetraenophanes. Hartree-Fock (HF) methods and the semi-empirical Austin Model 1 (AM1) method deviated significantly from the DFT/UB3LYP optimized geometries. Cyclooctatetraenes can undergo reversible sizing by oxidation and reduction reactions to form the aromatic dication and aromatic dianion, respectively, which could then be used to prepare molecular backbones for polymeric organometallic molecular wires. The number of bridges and the introduction of the sulfur atom have been investigated to provide disparate synthetic routes.