Phosgene, or carbonyl chloride, is an extremely toxic gas, and it was used for that purpose during World War I. Its name is confusing because the molecule does not contain phosphorus. The manufacture of phosgene from chlorine and carbon monoxide was first patented in 1917. Phosgene has been used in many organic syntheses, notably of isocyanates; but its commercial use has been largely discontinued because of its toxicity.
Learn more about this molecule from CAS, the most authoritative and comprehensive source for chemical information.