Cyclopenta[b]thiopyran and cyclopenta[b]selenopyran based heteroarenes: electronic communication between S- and/or Se-fused aromatics

S- and Se-heteroarenes containing cyclopenta[b]thiopyran and/or cyclopenta[b]selenopyran moieties have been synthesized via PtCl2-catalyzed ring-expanding cycloaromatizations. Intervalence charge transfer bands can be observed for the three heteroarenes upon chemical oxidation, suggesting the electronic communication between S- and/or Se-fused aromatics.