4,5-tetramethylene 1,3-diselenole 2-selenone

5,6-dihydro-[1,3]diselenolo[4,5-b][1,4]dioxine-2-selenone

4,5-dimethyl-1,3-diselenol-2-one

2-isopropylidene-1,3-dithiolo[4,5-d]-1,3-dithiol-2-one

(2-oxobutyl)-N,N-pentamethylenediselenocarbamate