Phosphorous V Fluorides

Phosphorous (V) fluorides have some interesting structural and dynamic features that influence their 19F NMR spectra. All such compounds appear to have a trigonal bipyramid structure, which features 

In order to correctly predict which ligands occupy which sites in such compounds, one must recognize that, as a general rule, fluorines will always prefer the axial site in a trigonal bipyramidal system, perhaps because of fluorine s small size, but probably also because of its preference to bind to orbitals with as little s-character as possible. The orbitals used by P to make its axial bonds have less s-character than those used to make its equatorial bonds. This is reflected by the larger F-P coupling constants to the equatorial fluorine substituents. 

One must assume that the example with the electronegative CF3 groups that only exhibits one signal in its fluorine NMR spectrum must be undergoing rapid intramolecular exchange of its axial and equatorial fluorines. 

COMPOUNDS AND SUBSTITUENTS WITH FLUORINE DIRECTLY BOUND TO A HETEROATOM 

---

Benzyl-methyl-amin<>)-tetrafluor-phosphoranH3 In einem GlasgefaB werden bei -196° 7,6 g (0,06 mol) Phosphor(V)-fluorid zu 11,6 g (0,06 mol) (Benzyl-methyl-amino)-trimethyl-silan kondensiert. Das verschlos-sene GcfaB wird 2 Tage bei -78°gehalten. Nach Abziehen der fliichtigen Bestandteile wird das Produkt i. Vak. destilliert Ausbeute 9,8 g (72%) Sdp. 78780 Torr (10,67 kPa). 

Organozinn-Verbindungen setzen sich mit Phosphor(V)-fluorid zu Organo-tetra-fluor-phosphoranen um19,20 ... 

Phosphonsaure-chlorid-fluoride lassen sich aus Phosphonsaure-ester-fluoriden und Phosphor(V)-chlorid gewinnen187 ... 

Recently a very mild method was discovered for the synthesis of dinucleoside fluorophosphates in the conversion of a dinucleoside phosphite with iV V -oxalyldiimi-dazole into the corresponding phosphoric imidazolide, which is then treated with acyl fluoride [204] <202]... 

---