HeI photoelectron spectra of o,o '-bridged biphenyls by 2-X-propylene (X =O, S, SO, NCH3) chains

HeI photoelectron (PE) spectra of 1,11-dimethyl-5,7-dihydro-dibenzo[c,e]oxe pine (1), 1,11-dimethyl-5,7-dihydro-dibenzo[c,e]thiepine (2), 1,11-dimethyl -5,7-dihydro-dibenzo[c,e]thiepine-S-oxide (3), 1,6,11-trimethyl-6,7-dihydro -5H-dibenzo[c,e]azepine (4), and 5,11-dimethyl-4,5,6,10,11,12-hexahydro-5,1 1-diaza-dibenzo[ef,kl]heptalene (5) have been measured. The low energy regi on of the spectra has been analyzed using semiempirical PM3, AM1 and MNDO S CF MO calculations (assuming the validity of Koopmans' theorem (Physica 1 ( 1934) 104) as well as empirical arguments (Franck-Condon (FC) envelopes) an d correlation with PE spectra of similar molecules. Their electronic struct ure might be responsible for their chemical properties.