Reaction of [Mn(CO)4{(PPh2)2CH}] (1) with half an equivalent of dipiperidinotetraselane affords the tetraselenide compound [(CO)4Mn{(PPh2)2C-Se4-C(PPh 2)2}Mn(CO)4] (2-Se4), which, upon treatment with KOH, is transformed into the corresponding triselenide and diselenide derivatives 2-Se3 and 2-Se2. Full or partial protonation of the methanide carbon atoms can be accomplished by reaction of the above compounds with HBF4, whereas treatment of 2-Se2 with I2 gives rise to the formation of the selenelyl iodide derivative [Mn(CO)4{(PPh2)2C-Se-I}] (5). © 2010 American Chemical Society.