Complexes and First-Row Transition Elements. PF 3 is highly toxic, comparable to phosgene. Phosphorus trifluoride is similar to carbon monoxide in that it is a gas which strongly binds to iron in hemoglobin, preventing the blood from absorbing oxygen. Phosphorus trifluoride is usually prepared from phosphorus trichloride via halogen exchange using various fluorides such as hydrogen fluoride, calcium fluoride, arsenic trifluoride, antimony trifluoride, or zinc fluoride: 2 PCl 3 + 3 ZnF 2 → 2 PF 3 + 3 ZnCl 2 Biological activity Cr(PF 3) 6, the analogue of Cr(CO) 6, may be prepared from dibenzenechromium:Ĭr(C 6H 6) 2 + 6 PF 3 → Cr(PF 3) 6 + 2 C 6H 6 However, nickel metal reacts directly with PF 3 at 100 ☌ under 35 MPa pressure to form Ni(PF 3) 4, which is analogous to Ni(CO) 4. Such complexes are usually prepared directly from the related metal carbonyl compound, with loss of CO. Thus, Pd(PF 3) 4 is known, but Pd(CO) 4 is not. PF 3 forms several complexes for which the corresponding CO derivatives (see metal carbonyl) are unstable or nonexistent. It forms a variety of metal complexes with metals in low oxidation states. With Lewis bases such as ammonia addition products (adducts) are formed, and PF 3 is oxidized by oxidizing agents such as bromine or potassium permanganate.Īs a ligand for transition metals, PF 3 is a strong π-acceptor. With hot metals, phosphides and fluorides are formed. It does not attack glass except at high temperatures, and anhydrous potassium hydroxide may be used to dry it with little loss. Phosphorus trifluoride hydrolyzes especially at high pH, but it is less hydrolytically sensitive than phosphorus trichloride. The phosphorus atom has a nuclear magnetic resonance chemical shift of 97 ppm (downfield of H 3PO 4). Gaseous PF 3 has a standard enthalpy of formation of −945 kJ/mol (−226 kcal/ mol). Phosphorus trifluoride has an F−P−F bond angle of approximately 96.3°. 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. Its main use is as a ligand in metal complexes. It is highly toxic and reacts slowly with water. Phosphorus trifluoride (formula P F 3), is a colorless and odorless gas.
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