Phosphorus trifluoride (formula PF3), is a colorless and odorless gas. It is highly toxic and it reacts slowly with water. Its main use is as a ligand in metal complexes. As a ligand it parallels carbon monoxide in metal carbonyls, and indeed its toxicity is due to its binding with the iron in blood hemoglobin in a similar way to carbon monoxide.
Read more about Phosphorus Trifluoride: Physical Properties, Properties, Preparation, Biological Activity, Precautions