A BH Borenium-Derived Thioxoborane, Its Persulfide, and Their Li+‑Induced Reactions with Alkynes and with Carbon Dioxide

Insertion of sulfur into the B–H bond of the BH borenium salt [IMes­(C6F5)­BH]+ followed by deprotonation gave the thioxoborane IMes­(C6F5)­BS. Subsequent treatment with additional sulfur gave the corresponding boron persulfide, a NHC-stabilized boradithiirane. The BS compound reacted with carbon dioxide in the presence of the lithium salt Li­[B­(C6F5)4] by formal [2+2] cycloaddition to give a boron thiocarbonate-type product. The boron persulfide formally inserted phenyl acetylene into the B–S bond in the presence of Li­[B­(C6F5)4] to give the respective five-membered heterocycle.