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] (<b>1</b>). Oxidation of <b>1</b> with 0.5 equiv of I₂ results in formation of the thiocarbonyl disulfide, Ph₃CC(S)SS(S)CCPh₃ (<b>2</b>), whereas reaction of <b>1</b> with 1 equiv of Ph₃CCl in MeCN results in deposition of the dithiocarboxylate ester, Ph₃CC(S)SCPh₃ (<b>3</b>). Compounds <b>1</b>-<b>3</b> were characterized by NMR spectroscopy and X-ray-crystallography, and their UV-vis spectra were simulated with TD-DFT calculations. Photolysis of <b>2</b> 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 <b>3</b>, Ph₃CH, 9-phenylfluorene, Ph₃CSH, and the dithiocarboxylic acid, Ph₃CC(S)SH (<b>4</b>). CS₂ is formed in a 50% yield in this reaction. Photolysis of <b>3</b> 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 <b>4</b>. However, the yield of CS₂ in this transformation is only 8%, suggesting that CS₂ release is only a minor pathway in the photolysis of <b>3</b>.