A highly toxic colourless or brown liquid, C5H11N2O2P; r.d. 1.09; m.p. –50°C; b.p. 247.5°C. It is an organophosphorus compound, ethyl N,N-dimethylphosphoramidocyanidate. Tabun was discovered in 1936 and belongs to the G-series of nerve agents (GA). It was used by Iraq in the Iran-Iraq war (1980–88).