5,5'-Bridged bis(1,2,3-dithiazoles): spin states and charge-transfer chemistry.

Bifunctional 1,2,3-dithiazoles bridged with azine and phenylenediamine spacers have been prepared, with a view to determining the extent of communication between the two dithiazole rings as a function of the electronic and steric demands of the bridge. The crystal structure of the closed-shell diazine derivative [S2NClC2NNC2ClNS2] is rigorously planar. Cyclic voltammetry on this compound indicates two reversible one-electron oxidations. The radical cation state has been characterized by EPR spectroscopy and by crystal structure determination of its 1:1 PF6- salt. The latter reveals little interaction between neighboring radical cations; consistently, the material exhibits a conductivity of σ < 10-5 S cm-1. Insertion of a phenylene group into the diazine bridge to afford [S2NClC2NC6H4NC2ClNS2] leads to significant torsional motion between the phenylene ring and the two end groups, as a result of which the two DTA rings are electronically independent; no radical cation state has been observed for this speci...