HE-I AND HE-II PHOTOELECTRON-SPECTRA OF THIOPHENONES

He II photoelectron spectra of tetrahydrothiophen-2-one, tetrahydrothi ophen-3-one and 2(5H)-thiophenone have been recorded along with the co rresponding He I spectra. The relative He I/He II band intensities pro vide clear evidence for the assignment of the first few bands, which a re also assigned on the basis of bandshape and SCF MO calculations. Co rrelations with IPs of tetrahydrothiophene, 2,5-dihydrothiophene and f ormaldehyde show that the interaction of the carbonyl group and the ri ng heteroatom is primarily inductive in nature in these thiophenones, though there may be a small degree of conjugative interaction between the carbonyl group and the ethylenic moiety in 2(5H)-thiophenone. (C) 1998 Elsevier Science B.V.