PUB - Publikationen an der Universität Bielefeld

(C2F5)(2)PCl is now accessible through a significantly improved synthesis protocol starting from the technical product (C2F5)(3)PF2. (C2F5)(3)PF2 was reduced in the first step with NaBH4 in a solvent-free reaction at 120 degrees 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)(2)PO- selectively under liberation of pentafluoroethane. Subsequent chlorination with PhPCl4 resulted in the selective formation of (C2F5)(2)PCl, which was isolated by fractional condensation in an overall yield of 66%. The gas electron diffraction (GED) pattern for (C2F5)(2)PCl 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 there-fore 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 degrees in the C-P-C angle, which, for the lowest-energy conformer, was refined to 98.2(4)degrees and was calculated to be 94.9 degrees.