³¹P and ¹⁹F Nuclear Magnetic Resonance Studies of Phosphorus-Fluorine Compounds

Abstract

The nuclear magnetic resonance spectra (31P, 19F) of a variety of compounds containing phosphorus-fluorine bonds have been studied, in continuation of earlier investigations on the same type of compounds.The previously observed relationship between coordination number of phosphorus and <5p was generally confirmed, i. e. <5p becomes more positive as the coordination number around phosphorus increases. No meaningful substitution rules, either for chemical shifts or for P -F coupling constants, could be established. The data obtained are discussed qualitatively in relation to the electronegativity of the substituents and to the coordination number of phosphorus. Data on the preparation and characterization of numerous phosphorus-fluorine compounds are also included.In a previous publication 1 31P n.m.r. data for a wide variety of phosphorus-fluorine compounds were presented. It was found that 31P chemical shifts ex tend over a range of about 350 p.p.m., and that there is a correlation between c5p and the coordina tion number of phosphorus in the respective com pound. We have now extended our original study to include numerous further examples, some of which had not been available previously. In addition to the 31P spectra, we are now reporting 19F n.m.r data, as well. ExperimentalSynthesis and physical properties of the majority of the compounds under discussion in this paper have been reported 2.A number of compounds have been included which are either new or have been prepared by alternate routes. Details as to synthesis, physical properties, and compound characterization are included in Table 1. The usual procedures required in handling air-and/or moisture-sensitive materials were observed in the course of the preparative work. !H n.m.r. spectra, wherever included, were obtained on a Varian Associates A 60 analytical spectrometer at 60 MHz. 31P and 19F n.m.r. spectra were recorded on a Varian Associates HR 60 spectrometer, equipped with a flux stabilizer, at 24.3 and 56.4 MHz, respecti vely. Some 31P and 19F spectra were obtained on a Throughout this work, Si(CH3) 4 and CFC13 were used as internal reference in the *H and 19F measure ments, respectively. 85 percent phosphoric acid, con tained in sealed capillaries, served as an external re ference (placed inside the n.m.r. tubes) in the 31P measurements. Calibrations to obtain (5f and <5p were carried out by the usual side-band technique whenever the spectra showed fine structure; otherwise the super position technique was used.Except where stated otherwise, spectra were ob tained on neat samples.

New Anions of Pentacoordinate Phosphorus Containing Fluorine and Trifluoromethyl Groups

“…NMR investigations of 1:1 mixtures of (PhO) 3 [11,12] The characteristic NMR spectroscopic data for the compounds 4, 5 (Table 1) and 6 are in full agreement with the data given by Christe et al [8] The main advantage of the [F 4 PO] -anion synthesis starting from triphenylphosphate is the relative stability of this anion in the solid state as well as in dmso solution at 20°C. This result supports the suggestion that the presence of excess P(O)F 3 used in the known procedure significantly accelerates the dismutation process.…”

Is Fluoride Bonded to Two Pd Acceptors Still Basic? Three CH2Cl2 Molecules Encapsulating a Pd2(μ-F)2 Square and New Implications for Catalysis

“…5, 6 The thermal decomposition of 3 in toluene under rigorously anhydrous conditions (N 2 ) at 115 °C (>95 % conversion after 72 h; monitored by 19 F and 31 P NMR) produced Pd metal, Me 3 PF 2 , Me 2 (Ph)PF 2 , and [Me 3 PPh] + FHF − . Both difluorophosphoranes (unambiguously identified by their characteristic 19 F and 31 P NMR spectra17) and the phosphonium cation emerged from CP and PF reductive elimination reactions similar to those described for [(Ph 3 P) 2 PdPh(F)] 6. In contrast, the formation of bifluoride ( 19 F NMR spectroscopy: broadened doublet, δ =−142.6 ppm, J (H,F)=121 Hz)18 was unexpected.…”

Tungsten(VI) and Tungsten(V) Fluoride Complexes

“…The by‐product P(C 6 H 3 ) 3 (F) 2 has previously been described. It is identified by its 19 F, and 31 P NMR spectra,23, 24 and its crystallographic characteristics 25. The novel tungsten(V) compound is a green stable material, it is obtained in high yield.…”