Reactions of phosphorous penta-fluoride and related compounds

Fraser, George William (1965) Reactions of phosphorous penta-fluoride and related compounds. PhD thesis, University of Glasgow.

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Abstract

The reaction of phosphorus pentafluoride with a variety of ligands has been studied using standard high vacuum-line techniques. Thermal decomposition of the complexes formed produced several new compounds containing phosphorus-fluorine bonds; the structures of which were investigated using Infrared and Nuclear Magnetic Resonance Spectroscopy. Phosphorus pentafluoride was found to form new compounds with dialkylamines. Thermal decomposition of these complexes produced the new compounds dialkylamino tetrafluoro pghosphoranes.PF4RN2 and bis dialkylamino trifluoro phosphoranes PF3(RN2)2.Infrared and Nuclear Magnetic Resonancespectroscopy show thse compounds are monomeric in the gaseous and liquid states and that the amino groups occupy the equatorial positons of the trigonal bipyramid. Reaction of phosphorus pentafluoride and primary alkyl amines was comlex yielding non-stoichiometric mixtures. Thermal decomposition produced a solid liquid mixture which was not identified. The reaction of phosphorus pentafluoride with phosphorus ligands was investigated to obtain information of the strength of the novel phosphorus-phosphorus bond produced. Complexes wre prepared with trialkyl phosphines, bisdialkalamino phosphines and trialkyl phosphites. The stability of the complexes were found to fall in the following order PR5>P(NR2)3>P(OR)3 Possible explanations for this stability order are discussed on the basis that the fluorider lone pairs are overlapping with the trivalent phosphorus unfiled'd' orbitals. Thermal decomposition of the tris dimethylamino tetrafluoro phosphorane PF3(NMe2)2 as well as dimelthylamino difluoro phosphine PF(NMe2)2, while the trimethyl phosphate complex decomposed to give the new compounds methyl difluoro phosphate (CH3O)3PCH3PF3. The kinetics of the composition of this salt, (which is an Arbuzov Rearrangement intermediate), in acetone and acenonitrille solution, were observed from Nuclear Magnetic Resonance spectroscopy and electrical conductivity measurements. As the behaviour in these two solvents is so different the solvent must play a major part in the kinetic interpretations. The reaction of a variety of lithium salts with phosphorus pentafluoride and other non-metal fluorides in ether and pentane solution were investigated. Several new lithium salts including the novel propyl pentafluorophosphate salt were prepared while simpler methods of producing pure lithium hexafluoro phosphate than these described in the literature were developed. The use some of the new amino phosphorus fluorine compounds, as ligands to transition metal salts and metal carbonyls, confirmed the belief that the nitrogen lone pairs are PI bonded into the vacant'd' orbitals of the phosphorus and complexes can only be obtained under specific conditions. Attempts to prepare metal carbonyl fluorosulphates from the metal carbonyl halides and silver fluorosulphate produced impure gluey compounds which could not be obtained crystalline. The ready solubility in water of the carbonyl compounds formed suggested the existence of the carbonyl fluorosulphate although only in the impure state.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: D WA Sharp
Keywords: Inorganic chemistry
Date of Award: 1965
Depositing User: Enlighten Team
Unique ID: glathesis:1965-72820
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 11 Jun 2019 11:06
Last Modified: 11 Jun 2019 11:06
URI: http://theses.gla.ac.uk/id/eprint/72820

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