and can be fatal when inhaled. History Phosphorus pentachloride was first prepared in 1808 by the English chemist Humphry Davy. Davy's analysis of phosphorus pentachloride was inaccurate; the first accurate analysis was provided in 1816 by the French chemist Pierre Louis Dulong. See also Phosphorus halides Phosphorus trichloride Phosphoryl chloride Phosphorus trifluorodichloride References External links The period 3 chlorides International Chemical Safety Card 0544 CDC - NIOSH Pocket Guide to Chemical Hazards Phosphorus chlorides Hypervalent molecules Phosphorus(V) compounds