The formation and crystal structures of bis(1‐naphthyl) diselenide (1) and bis{[2‐(N,N‐dimethylamino)methyl]phenyl} tetraselenide (2) are described. Whereas 1 can be produced in good yields, 2 is formed only as a minor product together with the known main product, bis{[2‐(N,N‐dimethylamino)methyl]phenyl} diselenide. The composition of the reaction mixture is semi‐quantitatively estimated by 77Se NMR spectroscopy and DFT calculations. The effect of the n2→σ*(Se–Se) and π→σ*(Se–Se) secondary bonding interactions on the Se–Se bonds is discussed both by DFT calculations and comparison with literature, as available. The bromination of 1 yields monomeric (1‐naphthyl)selenenyl bromide (3) in good yields. That of the reaction mixture of (C6H4CH2NMe2)Sex (x = 2–4) and Se8 afforded (C6H4CH2NMe2H)2[SeBr4] (4) and (C6H4CH2NMe2H)2[SeBr6] (5) in addition to (C6H4CH2NMe2)SeBr, which has been previously reported.