VX nerve agent molecule. Molecular model of VX, a nerve agent used in chemical warfare. VX blocks the action of an enzyme called acetylcholinesterase. This results in sustained contractions of all the muscles in the body. Sustained contraction of the diaphragm muscle causes death by asphyxiation. VX is considered the deadliest nerve agent yet developed. The molecule's chemical formula is C11.H26.N.O2.P.S. Atoms are colour-coded: carbon (grey), hydrogen (white), nitrogen (blue), oxygen (red), phosphorus (orange) and sulphur (yellow).