Tetracarbon dioxide is an oxide of carbon, a chemical compound of carbon and oxygen, with chemical formula C<sub>4</sub>O<sub>2</sub> or O=C=C=C=C=O. It can be regarded as butatriene dione, the double ketone of butatriene â more precisely 1,2,3-butatriene-1,4-dione.
Butatriene dione is the fourth member of the family of linear carbon dioxides O(=C)<sub>n</sub>=O, that includes carbon dioxide CO<sub>2</sub> or O=C=O, ethylene dione C<sub>2</sub>O<sub>2</sub> or O=C=C=O, carbon suboxide C<sub>3</sub>O<sub>2</sub> or O=C=C=C=O, pentacarbon dioxide C<sub>5</sub>O<sub>2</sub> or O=C=C=C=C=C=O, and so on.
The compound was obtained in 1990 by Günther Maier and others, by flash vacuum pyrolysis of cyclic azaketones in a frozen argon matrix. It was also obtained in the same year by Detlev Sülzle and Helmut Schwartz through impact ionization of ((CH<sub>3</sub>-)<sub>2</sub>(C<sub>4</sub>O<sub>2</sub>)(=O)<sub>2</sub>=)<sub>2</sub> in the gas phase. Although theoretical studies indicated that the even-numbered members of the O(=C)<sub>n</sub>=O family should be inherently unstable, C<sub>4</sub>O<sub>2</sub> is indefinitely stable in the matrix, but is decomposed by light into tricarbon monoxide C<sub>3</sub>O and carbon monoxide CO. It has a triplet ground state.