Photochemical studies on the through-space S···S interaction of 2- phenylnaphtho[1,8-de][1,3]dithiin 1-oxide, 5-phenyl[1]benzothieno[4,3,2- def][1,3]benzodithiepin 4-oxide, and 2-phenyldibenzo[d,f][1,3]dithiepin 1- oxide

Article abstract of DOI:10.1016/S0040-4020(99)00201-X

2-Phenylnaphtho[1,8-de][1,3]dithiin 1-oxide (4a), 5- phenyl[1]benzothieno[4,3,2-def][1,3]benzodithiepin 4-oxide (4b), and 2- phenyldibenzo[d,f][1,3]dithiepin 1-oxide (4c) underwent facile consecutive photochemical reactions to give the corresponding disulfide, naphtho[1,8- cd][1,2]dithiole (1a), [1]benzothieno[4,3,2-cde][1,2]benzodithiin (1b), and dibenzo[c,e][1,2]dithiin (1c) and benzaldehyde (7), respectively, via the sulfur-sulfur (S···S) interaction. The proposed mechanism for these photochemical reactions is based on the quantum yields measurements, photo- intensity effects, and sensitizer effects. Ab initio calculations were also carried out for a model compound of the primary photoproduct, which showed that the S···S distance becomes shorter and the S-O distance becomes longer upon the excitation to the S₁ state.