Contributions to the chemistry of phosphorus fluorine compounds and a few complex fluorides

Abstract

The thesis incorporates the results of the investigations on (1) Oxidative reactions of sulphur trioxide, iodine monochloride and nitryl chloride with phosphorus trifluoride and thiophosphoryl fluoride, (2) Reactions of sulphur trioxide with hexafluorophosphates, tetrafluoroborates and hexafluorosilicates, (3) Synthesis of hexafluoro complexes of vanadium, chromium, iron and cobalt using pyridinium (poly)hydrogen fluoride, and (4) In addition, reactions of phosphorus trifluoride with iodic acid, periodic acid and nitrites of sodium and potassium have also been investigated. Some of the special reagents required for the present investigations such as anhydrous metal halides, sulphur trioxide, pyridinium poly(hydrogen fluoride), iodine monochloride and nitryl chloride, phosphorus trifluoride, thiophosphoryl fluoride, the salts of hexafluorophosphates, tetrafluoroborates and hexafluorosilicates have been prepared by the elegant methods standardized recently in the laboratory. Conventional analytical methods have been adopted for the estimation of phosphorus, fluorine, sulphur, silicon, chlorine, boron and iodine present in different compounds encountered in the investigation. A variety of physical techniques such as electronic, infrared and nuclear magnetic resonance (^1H, ^13C, ^31P, ^19F) spectroscopy and X-ray powder diffraction methods have been employed for identification and characterization of the compounds. The experimental results show a close similarity in behaviour between phosphorus trifluoride and thiophosphoryl fluoride towards these oxidizing reagents. The products are similar except that sulphur is liberated in the latter case. The studies have interestingly indicated a quantitative cleavage of the stable complex fluorides releasing the respective volatile fluorides (SiF?, PF? and BF?) along with the abstraction of metal fluoride by sulphur trioxide to form metal fluorosulphates, at room temperature. A general synthetic procedure at room temperature for the preparation of fluoro complexes of vanadium, chromium, cobalt and iron has been evolved and standardized.