- Chlorobis(pentafluoroethyl)phosphane: Improved synthesis and molecular structure in the gas phase
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(C2F5)2PCl is now accessible through a significantly improved synthesis protocol starting from the technical product (C2F5)3PF2. (C2F 5)3PF2 was reduced in the first step with NaBH4 in a solvent-free reaction at 120 °C. The product, P(C 2F5)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 PhPCl 4 resulted in the selective formation of (C2F 5)2PCl, which was isolated by fractional condensation in an overall yield of 66 %. The gas electron diffraction (GED) pattern for (C 2F5)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°.
- Hayes, Stuart A.,Berger, Raphael J. F.,Mitzel, Norbert W.,Bader, Julia,Hoge, Berthold
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- Functionalized bis(pentafluoroethyl)phosphanes: Improved syntheses and molecular structures in the gas phase
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(C2F5)2PNEt2 represents an excellent starting material for the selective synthesis of bis(pentafluoroethyl) phosphane derivatives. The moderately air-sensitive aminophosphane is accessible on a multi-gram scale by treating Cl2PNEt2 with C 2F5Li. Treatment with gaseous HCl or HBr yielded the corresponding phosphane halides (C2F5)2PCl and the so far unknown (C2F5)2PBr in good yields. The hitherto unknown (C2F5)2PF was obtained by treating (C2F5)2PBr with excess antimony trifluoride. Treatment of (C2F5)2PCl with Bu3SnH led to the quantitative formation of (C2F 5)2PH. Deprotonation formally yielded the (C 2F5)2P- anion in a form that was stabilized by coordination to mercury ions to form the complex [Hg{P(C 2F5)2}2(dppe)]. An improved high-yielding synthesis of (C2F5)2POH was achieved by treating (C2F5)2PNEt2 with p-toluenesulfonic acid. The gas-phase structures of (C2F 5)2PH and (C2F5)2POH were determined by electron diffraction. The vibrational corrections employed in the data analysis of the diffraction data were derived from molecular dynamics calculations. Both compounds exist in the gas phase mostly as C 1-symmetric cis,cis conformers with regard the orientation of the C2F5 groups relative to the functional groups H and OH. The presence of a second conformer at ambient temperature is likely in both cases. The refined amounts of dominant conformers are 94(6) and 85(6) % for (C2F5)2PH and (C2F5) 2POH, respectively. The conformational behaviour was further explored by potential energy surface scans based on DFT calculations. Important experimental structural parameters for the most stable conformers are r e(P-C)average = 1.884(3) A for (C2F 5)2PH and re(P-C)average = 1.894(4) A and re(P-O) = 1.582(3) A for (C2F 5)2POH. The different coordination properties of (C 2F5)3P, (C2F5) 2POH, (CF3)3P and (CF3) 2POH were evaluated by complex formation with [Ni(CO)4]: the maximum achievable number of CO ligands substituted by (C2F 5)3P is 1, by (C2F5)2POH is 2, by (CF3)3P is 3 and by the smallest ligand (CF 3)2POH is 4. New synthetic routes to a series of bis(pentafluoroethyl)phosphanes have been developed and the structures of two of them, (C2F5)2PH and the phosphinous acid (C2F5)2POH, were studied by gas electron diffraction, making use of molecular dynamics calculations to support data analysis in an improved approach. Copyright
- Zakharov, Alexander V.,Vishnevskiy, Yury V.,Allefeld, Nadine,Bader, Julia,Kurscheid, Boris,Steinhauer, Simon,Hoge, Berthold,Neumann, Beate,Stammler, Hans-Georg,Berger, Raphael J. F.,Mitzel, Norbert W.
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p. 3392 - 3404
(2013/07/26)
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- Bis(perfluoralkyl)phosphinous acids and derivatives and use thereof
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The invention relates to bis(perfluoroalkyl)phosphinous acids, bis(perfluoroalkyl)thiophosphinous acids and derivatives, the synthesis thereof and the use thereof, in particular for the synthesis of air-stable metal complexes for catalytic processes.
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Page/Page column 19
(2011/06/19)
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- Reaction of perfluoroalkyl Grignard reagents with phosphorus trihalides: A new route to perfluoroalkyl-phosphonous and-phosphonic acids
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The reaction of perfluoroalkyl Grignard reagents with phosphorus(III) halides was explored. In the process a new convenient, one-pot, high yield method for the synthesis of (perfluoroalkyl)phosphonic acids has been developed. Perfluoroalkyl Grignard reagents react with phosphorus trichloride or phosphorus tribromide to form (perfluoroalkyl)phosphonous dihalides. Hydrolysis gives the corresponding (perfluoroalkyl)phosphonous acids. Oxidation of the phosphonous acids with H2O2 produces (perfluoroalkyl) phosphonic acids in 60-78% overall yields, based on the corresponding perfluoroalkyl iodide. The X-ray crystal structures of the toluidinium salts, [MeC6H4NH3]2[C2F 5PO3] and [MeC6H4NH 3][C8F17P(O)2OH], are reported.
- Hosein, Adil I.,Le Goff, Xavier F.,Ricard, Louis,Caffyn, Andrew J. M.
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experimental part
p. 1484 - 1490
(2011/04/23)
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