The industrial product (C(2)F(5))(3)PF(2) is transformed into the phosphinic acid chloride (C(2)F(5))(2)P(O)Cl, which reacts with an excess of Bu(3)SnH in a clean, multistep reaction to give the stannyl derivative (C(2)F(5))(2)POSnBu(3). Subsequent treatment with gaseous HBr leads to the formation of (C(2)F(5))(2)POH, which is isolated in 70 % yield. Besides (CF(3))(2)POH, bis(pentafluoroethyl)phosphinous acid, (C(2)F(5))(2)POH, represents the second known example of a phosphinous acid that is predicted by using density functional theory calculations at the B3PW91/6-311G(3d,p) level to be more stable than the phosphane oxide tautomer, the energy difference being 11.7 kJ mol(-1). Only the phosphinous acid isomer is detectable in the gas phase and in solution. However, investigations of the neat liquid reveal a temperature-dependent tautomeric equilibrium with the phosphane oxide isomer (C(2)F(5))(2)P(O)H, which is characterized by vibrational and multinuclear NMR spectroscopic methods in combination with quantum-chemical calculations.

Die Synthese und vollständige Charakterisierung von funktionellen und stark Lewis‐sauren Tris(pentafluorethyl)silanen wird beschrieben. Die Tetrakis(perfluoralkyl)silane Si(C2F5)4 und Si(C2F5)3CF3 sind durch direkte Fluorierung zugänglich. Die Reaktion von SiCl4 mit LiC2F5 führt nur zu (Pentafluorethyl)fluorosilicaten. Um die Silicatbildung durch Fluoridübertragung aus LiC2F5 zu unterbinden, muss die Lewis‐Acidität des Silans durch eine elektronenschiebende Gruppe, z. B eine Diethylaminogruppe, vermindert werden. Si(C2F5)3NEt2 erweist sich als eine nützliche Ausgangsverbindung für die Synthese weiterer Tris(pentafluorethyl)silane.

A series of tris-, bis-, and mono(pentafluoroethyl)bismuthanes of the type (C F ) BiX (X=F, Cl, Br, I) and transition metal complexes are accessible by a sophisticated pentafluoroethylation protocol. Chemical properties, induced by the strongly electron-withdrawing character of C F groups, are described for representative examples. Moreover, the first molecular structures of perfluoroalkyl bismuthanes and bismuthates obtained by X-ray diffraction are presented.

(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 C2F5Li. 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 (C2F5)2PH. Deprotonation formally yielded the (C2F5)2P– anion in a form that was stabilized by coordination to mercury ions to form the complex [Hg{P(C2F5)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 (C2F5)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 C1‐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 re(P–C)average = 1.884(3) Å for (C2F5)2PH and re(P–C)average = 1.894(4) Å and re(P–O) = 1.582(3) Å for (C2F5)2POH. The different coordination properties of (C2F5)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 (C2F5)3P is 1, by (C2F5)2POH is 2, by (CF3)3P is 3 and by the smallest ligand (CF3)2POH is 4.

The synthesis and complete characterization of functional, highly Lewis acidic tris(pentafluoroethyl)silanes as well as tetrakis(perfluoroalkyl)silanes Si(C2F5)4 and Si(C2F5)3 CF3 by direct fluorination is described. The reaction of SiCl4 with LiC2F5 invariably affords (pentafluoroethyl)fluorosilicates. To avoid silicate formation by fluoride transfer from LiC2F5 the Lewis acidity of the silane has to be decreased by electron-donating substituents, such as dialkylamino groups. The easily accessible Si(C2F5)3 NEt2 is a valuable precursor for a series of tris(pentafluoroethyl)silanes.