Dicyanoacetylene, also called carbon subnitride or but-2-ynedinitrile (IUPAC), is a compound of carbon and nitrogen with chemical formula C₄N₂. It has a linear molecular structure, N=C-C=C-C=N (often abbreviated as NC₄N), with alternating triple and single covalent bonds. It can be viewed as acetylene with the two hydrogen atoms replaced by cyanide groups.