Electronic structure of bichalcophenes

He I and He II photoelectron spectra of some isomeric bichalcophenes containing selenium were recorded. The electronic structure was analyzed and spectra assigned on the basis of empirical considerations: band contours, He I/He II intensity variations, and correlations with spectra of related molecules. Semiempirical MO calculations were used to estimate interring torsional barriers. The spectra indicate various interactions taking place among thiophene, furan, and selenophene π orbitals. The relationship between electronic structure and formation of novel polymer materials is discussed.