ELECTRONIC-STRUCTURE OF BICHALCOPHENES

He I and He II photoelectron spectra of some isomeric bichalcophenes c ontaining selenium were recorded. The electronic structure was analyze d and spectra assigned on the basis of empirical considerations: band contours, He I/He II intensity variations, and correlations with spect ra of related molecules. Semiempirical MO calculations were used to es timate interring torsional barriers. The spectra indicate various inte ractions taking place among thiophene, furan, and selenophene pi orbit als. The relationship between electronic structure and formation of no vel polymer materials is discussed.