Base-mediated formation of selenenylsulfides/diselenides: Methanolic KOH (0.2 M, 2.0 equiv.) was added dropwise to a solution of thioacetate-selenocyanate or bis(selenocyanate) (1.0 equiv.) in THF (0.05 M). Within seconds, the reaction turned from colourless to yellow and TLC indicated full conversion. The reaction was quenched with NaHCO3 (sat. aq.), and the aqueous layer was extracted with DCM. The combined organic layers were dried over MgSO4, filtered and concentrated in vacuo to give the selenenylsulfide/diselenide as a deeply coloured solid, used without further purification.