Thiophosphoryl fluoride is an
inorganic molecular gas with formula PSF3 containing
phosphorus,
sulfur and
fluorine. It spontaneously ignites in air and burns with a
cool flame. The discoverers were able to have flames around their hands without discomfort,[5] and called it "probably one of the coldest flames known".[5] The gas was discovered in 1888.[5]
It is useless for chemical warfare as it burns immediately and is not toxic enough.[6]
Preparation
Thiophosphoryl fluoride was discovered and named by J. W. Rodger and
T. E. Thorpe in 1888.[5][7]
They prepared it by heating
arsenic trifluoride and
thiophosphoryl chloride together in a sealed glass tube to 150 °C. Also produced in this reaction was
silicon tetrafluoride and phosphorus fluorides. By increasing the PSCl3 the proportion of PSF3 was increased. They observed the spontaneous inflammability. They also used this method:
3 PbF2 + P2S5 → 3 PbS + PSF3
at 170 °C, and also substituting a mixture of red phosphorus and sulfur, and substituting
bismuth trifluoride.[5]
Another way to prepare PSF3 is to add fluoride to PSCl3 using
sodium fluoride in acetonitrile.[8]
A high yield reaction can be used to produce the gas:[9][citation needed]
PSF3 is decomposed by moisture and oxygen or heat. With heat, phosphorus, sulfur and phosphorus fluorides are formed:
PSF3 → PF3 + S
The hot gas reacts with glass producing SF4, sulfur and elemental phosphorus. The pure gas is completely absorbed by alkali solutions. However, it does not react with
ether,
benzene,
carbon disulfide, or pure
sulfuric acid. It is stable against CaO, which can be used to remove impurities such as SiF4 and PF3. In air it burns spontaneously with a greyish green flame, producing solid white fumes. With dry oxygen combustion may not be spontaneous and the flame is yellow. On burning SO2 and P2O5 are produced. The gas burns with one of the coldest flames known.[5]
Reaction with water is slow:
PSF3 + 4 H2O → H2S + H3PO4 + 3 HF
If PSF3 is allowed to react with water in a lead glass container, the
hydrofluoric acid and
hydrogen sulfide combination produces a black deposit of
lead sulfide on the inner surface of the glass.[5]
It reacts with four times its volume of ammonia gas producing
ammonium fluoride and a mystery product, possibly P(NH2)2SF.[5]
One fluorine can be substituted by iodine to give thiophosphoryl difluoride iodide, PSIF2.[18]PSIF2 can be converted to hydrothiophosphoryldifluoride, S=PHF2, by reducing it with
hydrogen iodide.[19] In F2P(=S)−S−PF2, one sulfur forms a bridge between two phosphorus atoms.[18]
Dimethylaminothiophosphoryl difluoride ((H3C−)2N−P(=S)F2) is a foul smelling liquid with a boiling point of 117 °C. It has a
Trouton constant (entropy of vaporization at the boiling point of the liquid) of 24.4, and a
heat of evaporation of 9530 cal/mole. Alternately it can be produced by
fluorination of dimethylaminothiophosphoryl dichloride ((H3C−)2N−P(=S)Cl2).
Physical properties
The thiophosphoryl trifluoride molecule shape has been determined using electron diffraction. The interatomic distances are P=S 0.187±0.003 nm, P−F 0.153±0.002 nm and bond angles of F−P−F bonding is 100.3±2°, The
microwave rotational spectrum has been measured for several different
isotopologues.[20]
The
enthalpy of vaporisation 19.6 kJ/mol at boiling point.[22] The enthalpy of vaporisation at other temperatures is a function of temperature T: H(T)=28.85011(346-T)0.38 kJ/mol.[23]
The molecule is polar. It has a non-uniform distribution of positive and negative charge which gives it a
dipole moment. When an
electric field is applied more energy is stored than if the molecules did not respond by rotating. This increases the
dielectric constant. The dipole moment of one molecule of thiophosphoryl trifluoride is 0.640
Debye.[24]
The
infrared spectrum includes
vibrations at 275, 404, 442, 698, 951 and 983 cm−1.[25] These can be used to identify the molecule.
References
^
abA likely spelling mistake in Handbook of Chemistry and Physics 87 ed
^Padma, D. K.; Vijayalakshmi, S. K.; Vasudevamurthy, A. R. (1976). "Investigations on the preparation, oxidation and reduction reactions of thiophosphoryl fluoride". Journal of Fluorine Chemistry. 8 (6): 461.
doi:
10.1016/S0022-1139(00)81660-7.
^
abRoesky, H.W. (1970). "Thiophosphoryl-difluoride-isocyanate". Journal of Inorganic and Nuclear Chemistry. 32 (6): 1845–1846.
doi:
10.1016/0022-1902(70)80591-7.
^
abcHagen, Arnulf P.; Callaway, Bill W. (1978). "High-pressure reactions of small covalent molecules. 10. The reaction of phosphorus trifluoride with hydrogen sulfide and sulfur dioxide". Inorganic Chemistry. 17 (3): 554.
doi:
10.1021/ic50181a007.
^Padma, D.K.; Vijayalakshmi, S.K. (1978). "Thiophosphoryl fluoride and phosphoryl fluoride as initiators for the polymerisation of tetrahydrofuran". Journal of Fluorine Chemistry. 11: 51–56.
doi:
10.1016/S0022-1139(00)81597-3.
^Sampath Kumar, H.P.; Padma, D.K.; Vasudeva Murthy, A.R. (1984). "Reaction of thiophosphoryl fluoride with sulphur trioxide". Journal of Fluorine Chemistry. 26: 117–123.
doi:
10.1016/S0022-1139(00)85125-8.
^Sampath Kumar, H.P.; Padma, D.K. (1990). "Reaction of phosphorus trifluoride and thiophosphoryl fluoride with iodine monochloride and oxidation of phosphorus trifluoride with nitryl chloride, iodic acid, periodic acid, sodium nitrite and potassium nitrite". Journal of Fluorine Chemistry. 49 (3): 301.
doi:
10.1016/S0022-1139(00)85026-5.
^Roesky, Herbert W.; Tebbe, Fred N.; Muetterties, Earl L. (1970). "Thiophosphate chemistry. Anion set X2PS2−, (XPS2)2S2−, and (XPS2)2S22−". Inorganic Chemistry. 9 (4): 831.
doi:
10.1021/ic50086a028.
^Islam, Mohammad Q.; Hill, William E.; Webb, Thomas R. (1990). "Quadruply bonded dimolybdenum complexes of PF2S2−. Comparison with complexes of PR2S2p− (R = Et, Me)". Journal of Fluorine Chemistry. 48 (3): 429.
doi:
10.1016/S0022-1139(00)80227-4.
^Rhyne, T; Dillard, J (1971). "Reactions of gaseous inorganic negative ions: III. SF6− with POF3 and PSF3". International Journal of Mass Spectrometry and Ion Physics. 7 (5): 371.
Bibcode:
1971IJMSI...7..371R.
doi:
10.1016/0020-7381(71)85003-9.
^
abCharlton, Thomas L.; Cavell, Ronald G. (1969). "Difluorothiophosphoryl-μ-thio-difluorophosphine and difluorophosphoryl-μ-oxo-difluorophosphine. Novel mixed-valence fluorophosphorus compounds". Inorganic Chemistry. 8 (11): 2436.
doi:
10.1021/ic50081a037.
^Charlton, Thomas L.; Cavell, R. G. (1968). "Preparation and properties of iodothiophosphoryl difluoride, SPF2I". Inorganic Chemistry. 7 (11): 2195.
doi:
10.1021/ic50069a005.
^Williams, Quitman; Sheridan, John; Gordy, Walter (1952). "Microwave Spectra and Molecular Structures of POF3, PSF3, POCl3, and PSCl3". The Journal of Chemical Physics. 20 (1): 164–167.
Bibcode:
1952JChPh..20..164W.
doi:
10.1063/1.1700162.
^Handbook of Chemistry and Physics 87 ed page 6-39
Humphries, C. M.; Walsh, A. D.; Warsop, P. A. (1963). "Absorption spectrum of chlorine dioxide in the vacuum ultra-violet". Transactions of the Faraday Society. 35: 137.
doi:
10.1039/df9633500137.
Montana, Anthony J.; Zumbulyadis, Nikolaos; Dailey, Benjamin P. (1976). "19F and 31P magnetic shielding anisotropies and the F–P–F bond angle of PSF3 in a smectic liquid crystal solvent". The Journal of Chemical Physics. 65 (11): 4756.
Bibcode:
1976JChPh..65.4756M.
doi:
10.1063/1.432929.
Williams, Quitman; Sheridan, John; Gordy, Walter (1952). "Microwave Spectra and Molecular Structures of POF3, PSF3, POCl3, and PSCl3". The Journal of Chemical Physics. 20 (1): 164–167.
Bibcode:
1952JChPh..20..164W.
doi:
10.1063/1.1700162.
Lange, Willy; Askitopoulos, Konstantin (1938). "Zur Kenntnis des Phosphorsulfotrifluorids PSF3 und über ein Salz der Thiodifluorphosphorsäure H\PSF2O]". Berichte der Deutschen Chemischen Gesellschaft (A and B Series). 71 (4): 801.
doi:
10.1002/cber.19380710419.