Sulfur Multicenter Bonding and Distortions in a Hypothetical Polydithioquinone

Abstract

The electronic properties of polydithioquinone, a hypothetical C 4 S 2 carbon-sulfur polymer related to both tetrathiotetracene and thiothiophthene, are examined using approximate molecular orbital calculations. We focus on a curious pattern of sulfur-sulfur bonding interactions suggested by the band structure calculations, a pattern observed in thiothiophthenes and other molecular analogues of our polymer. The π system of each C 4 S 2 repeat unit contains eight electrons, consistent with a thiothiophthene-like rather than localized polydithioquinone valence structure. A pairing distortion in the carbon sublattice is implied; furthermore, the half-filled sulfur σ bands suggest that the sulfur sublattice is also likely to undergo distortions. Restricting our consideration to those distortions that retain planarity of the polymer, we find deformations of the carbon backbone considerably less favorable energetically than those of the sulfur sublattice. Four nicely bond-localized isomers result from the distortions of both carbon and sulfur sublattices; these all are found to be low bandgap semiconductors. We also examine helical distortions and find a stable isomer with an approximately 10-fold helical axis.

Theoretical Studies of Furan and Thiophene Nanothreads: Structures, Cycloaddition Barriers, and Activation Volumes

“…Hypothetical polyketone (CO) n is one example (Scheme ); it is calculated to prefer a helical structure . As hypothetical polymers, polythiene (CS) n , an analogue of polyketone (CO) n , and polydithioquinone, have been suggested, both containing two S chains with S···S interactions. Extended (CO) n and (CS) n polymers show a geometry that we see is analogous to that of all- syn thiophene and furan nanothreads, so it is useful to look at these structures in context…”

Linear, cyclic, and Möbius strip polyacenes: The influence of the topology on the size‐dependent HOMO–LUMO energy gap

“…Although the reported synthesized Möbius strips are nonconjugated compounds 6, recent studies on related compounds have shown that the cyclacene‐based materials may exhibit interesting magnetic 1, 3, conducting 22, and electronic 23 properties. Furthermore, due to the close relationship between NLO properties and BLA 24, the Möbius strips and related compounds can be viewed as potential new NLO materials 25, particularly in relation to the special nonlinear optical properties of chiral molecules.…”

Sulfurization of Polymers: A Novel Access to Electroactive and Conducting Materials

“…The three-center S-S bond formation in polyconjugated condensed carbon-sulfur polymers like that shown in Scheme 14 has recently been supported theoretically by Hoffmann and co-workers [34,35].…”