Chlorobis(pentafluoroethyl)phosphane: improved synthesis and molecular structure in the gas phase

(C₂F₅)₂PCl is now accessible through a significantly improved synthesis protocol starting from the technical product (C₂F₅)₃PF₂. (C₂F₅)₃PF₂ was reduced in the first step with NaBH₄ in a solvent‐free reaction at 120 °C. The product, P(C₂F₅)₃, was treated with an excess of an aqueous sodium hydroxide solution to afford the corresponding phosphinite salt Na⁺(C₂F₅)₂PO^? selectively under liberation of pentafluoroethane. Subsequent chlorination with PhPCl₄ resulted in the selective formation of (C₂F₅)₂PCl, which was isolated by fractional condensation in an overall yield of 66 %. The gas electron diffraction (GED) pattern for (C₂F₅)₂PCl was recorded and found to be described by a two‐conformer model. A quantum chemical investigation of the potential‐energy surface revealed the possible existence of many low‐energy conformers, each with a number of low‐frequency vibrational modes and therefore large‐amplitude motions. The conformer calculated to be most stable was also found to be most abundant by GED and comprised 61(5) % of the total. The molecular structure parameters determined by GED were in good agreement with those calculated at the MP2/TZVPP level of theory; the only significant difference was a discrepancy of about 3° in the C‐P‐C angle, which, for the lowest‐energy conformer, was refined to 98.2(4)° and was calculated to be 94.9°.