Photolytic Release of CS₂ from Bis(Tritylthiocarbonyl) Disulfide, Ph₃CC(S)SS(S)CCPh₃

Reaction of deep-red [K(18-crown-6)(THF)2][CPh3] with excess CS2 in THF results in rapid formation of the dithiocarboxylate, [K(18-crown-6)][S2CCPh3] (1). Oxidation of 1 with 0.5 equiv of I2 results in formation of the thiocarbonyl disulfide, Ph3CC(S)SS(S)CCPh3 (2), whereas reaction of 1 with 1 equiv of Ph3CCl in MeCN results in deposition of the dithiocarboxylate ester, Ph3CC(S)SCPh3 (3). Compounds 1-3 were characterized by NMR spectroscopy and X-ray-crystallography, and their UV-vis spectra were simulated with TD-DFT calculations. Photolysis of 2 using a medium-pressure Hg lamp for 24 h results in formation of Ph3CSSCPh3 and CS2 as the major products, along with small amounts of 3, Ph3CH, 9-phenylfluorene, Ph3CSH, and the dithiocarboxylic acid, Ph3CC(S)SH (4). CS2 is formed in a 50% yield in this reaction. Photolysis of 3 using a medium-pressure Hg lamp for 6 h also results in formation of Ph3CSSCPh3 as a major product, along with small amounts of Ph3CH, 9-phenylfluorene, Ph3CSH, and 4. However, the yield of CS2 in this transformation is only 8%, suggesting that CS2 release is only a minor pathway in the photolysis of 3.