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Phosphorus trifluoride complexes of arsenic and antimony pentafluorides
3674
Notes
parameters as Dq = 6339 cm-~; F2 = 402 cm-l; F4 = 134 cm -a. Which locates the A~ --* E transition at 30,851 cm-L The experimental value is 23,255 cm-L In aqueous solution the spectra (Fig. 5b) of the pyridine complex is completely different. Outside the charge transfer band there is one absorption peak at 460 m/~(~ = 60) and one at 580 n~(e = 10). It appears that the geometry of the molecule is changed as the crystal goes into solution, but the present data cannot give a definite answer to this problem.
Department of Chemistry University College of Science Calcutta, India
M. BASU S. BASU
J. inorg,nucLChem.,1969,Vol.3I, pp. 3674to 3676. PergamonPress. Printedin GreatBritain
Phosphorus trifluoride complexes of arsenic and antimony pentafluorides (Received 28 April 1969) ALTHOUGH phosphorus trifluoride forms many complexes with transition elements[l] very few complexes are known in which a non-transition element acts as the acceptor. Borine is known to give a 1:1 adduct, PF3. BH312] and higher boranes behave similarly[3,4]. However, phosphorus trifluoride does not form a complex with boron trifluoride, although aluminium trichloride is reported to give an adduct at low temperatures which decomposes at room temperature to aluminium tfifluoride and phosphorus trichloride[5]. Recently the stable compound PF3. B(BF2)3 has also been described[6]. We have now prepared a stable 1:1 adduct between PF3 and antimony pentailuoride and have obtained evidence that a similar adduct exists between PF3 and arsenic pentafluoride at -78 °. Triphenylphosphine and triphenylarsine also form 1 : 1 adducts with antimony pentafluoride. Antimony pentafluoride reacts with phosphorus trifluoride at room temperature to give a I:1 adduct PF3. SbFs. The adduct is a white solid, which is stable in the absence of moisture. Three likely structures can be envisaged for an adduct of this type: (i) a donor-acceptor complex, formed by donation of the lone-pair of electrons on the phosphorus atom, (ii) an ionic complex, PF2 + . SbF6-, (iii) a fluorine-bridged monomer. The i.r. and Raman spectra of the adduct are presented in Table 1. The bands in the region 9001200cm -1 can be assigned to phosphorus-fluorine stretching frequencies. These frequencies are much higher than have previously been observed in any other PF3 complex and are therefore more consistent with structure (ii) rather than structure (i). However, the absorptions in the region 700600 cm -1 are not consistent with a simple SbF6- species (which has a single absorption at 660 cm -1) and both the i.r. and Raman spectra in this region suggest a system of low symmetry. Hence it is possible that in this complex there is cationic-anionic interaction via fluorine bridging as has been observed in the adduct BrF3. SbFs[8]. Phosphorus trifluoride also reacts with arsenic pentafluoride at --78 ° to give a white adduct. The i.r. spectrum of the solid (Table) is similar to that of the antimony pentafluoride adduct and it therefore probably has a similar structure. However, at room temperature it is completely dissociated into its constituents. More stable l : l complexes are obtained from triphenylphosphine and triphenylarsine. These adducts, which are stable for long periods in moist air, are probably simple donor-acceptor complexes containing a direct phosphorus (or arsenic) to antimony bond. 1. T. Kruck, Angew. Chem., Int. Edn. 6, 53 (1967). 2. R.W. Parry and T. C. Bissot, J. Am. chem. Soc. 78, 1524 (1956). 3. J. R. Spielman and A. B. Burg, Inorg. Chem. 2, 1139 (1963). 4. W. R. Deever and D. M. Ritter, J.Am. chem. Soc. 89, 5073 (1967). 5. R. W. Parry, R. C. Taylor, G. Kodama, S. G. Shore, E. Alton, J. R. Weaver, C. E. Nordman and C. Cluff, U.S. Atomic Energy Commission Rep. No. WADC-TR-57-11 (1957); Chem. Abs. 55. 21939 (1961). 6. P. L. Timms,J.Am. chem. Soc. 89, 1629 (1967). 7. R. D. Peacock and D. W. A. Sharp, J. chem. Soc. 2762 (1959). 8. A.J. Edwards and G. R. Jones, Chem. Comm. 1304 (1967).
Notes
3675
Table 1. I.R. (4000-410 cm -1) and Raman spectra PF3* I.R.
892 860
PF3. SbF5 PFa. AsF5 Assignment I.R. Ramani 1.R. 1280w 1155 vw 1080m 970m 695vs 665 sh 620 sh
487 344
1290m 1075ms 915 s 703m 668 s 642m 628 sh 607m
500 sb
va~(P-F) ~s(P-F)
705 vs ~M-F)
500 m
8(PF2)
300 w,br
*M. K. Wilson and S. R. Polo, J. chem. Phys. 20, 1716(1952). t N o bands were observed between 1300-800 c m -1.
EXPERIMENTAL Phosphorus trifluoride was prepared by refluxing phosphorus trichloride with antimony trifluoride. The product gases were led through three -78 ° traps, and were condensed at -183 °. The phosphorus trifluoride was distilled under vacuum at -126" before use. An i.r. spectrum indicated that the product was essentially pure. Arsenic and antimony pentafluorides were prepared by direct fluorination of the elements.
Techniques Standard preparative vacuum-line methods were used throughout. The i.r. spectrum (4000410 cm -~) of the PF3. SbF5 complex was obtained using finely ground solid samples mounted between silver chloride plates. The i.r. spectrum of the PFs. AsF5 adduct was obtained from a solid film of the adduct condensed on a silver chloride plate a t - 7 8 ° under vacuum. The Raman spectrum was obtained on samples held in sealed pyrex tubes. I.r. spectra were recorded on a Perkin-Elmer 225 grating instrument. Raman spectra were recorded on a Cary 81 spectrophotometer fitted with a helium-neon laser. PF3. SbF5 Phosphorus trifluoride gas was condensed onto SbF5 (5 g) held in a 25 mi bulb. The bulb was repeatedly warmed to room temperature and cooled to -196 ° to promote reaction. The preparation was completed by holding liquid PFz (5 ml) over the reaction mixture at --126 ° for several hours. Excess PF3 was then distilled from the system to leave the white solid product. Analysis. Found: F, 50-0; P, 9.8; Sb, 39.8. FsPSb requires F, 51.5; P, 9.9; Sb, 38-7%.
The reaction o f AsF5 with PFz Equal volumes of AsF5 and PF3 were condensed together at --196 °, and warmed to --78 °. A white solid formed at this temperature. As the reaction vessel was slowly warmed to room temperature, the volume of the solid decreased. At room temperature no solid remained. An i.r. spectrum of the residual gases showed only the starting materials to be present. SbFs. P(C6H~)a SbFn. CH3CN (0-5 g) dissolved in acetonitrile (5 ml) was added to a suspension of triphenylphosphine (0-5 g) in acetonitrile (5 ml). After standing at room temperature for 1 hr excess acetonitrile was removed under vacuum to leave the white crystalline product. Analysis. Found: C, 45.1; H, 3.1; F, 19.9; P, 6-2. C18H15F~PSb requires C, 45-1; H, 3"1; F, 19.8; P, 6.5%.
3676
Notes
I.R. spectrum. (2500-400cm-1); 1585(s); 1485(s); 1438(s); 1337(m); 1320(m); 1300(w); 1283(w); 1267(w); l l90(ms); l168(ms); 1098(s); 1073(m); 1028(m); 998(s); 979(m); 735(s); 719(s); 690(s); 650(vs); 624(vs); 525(s); 497(s). SbFs.As(CoHs)a Procedure as above from SbFs. CH3CN (0.42 g) and triphenylarsine (0.5 g). Analysis. Found: C, 41 "2; H, 2.9; F, 17.9; C18H15AsF~Sb requires C, 41-3; H, 2.9; F, 18.2%. I.R. spectrum. (2500-400cm-1); 1715(s); 1575(m); 1480(s); 1438(s); 1335(w); 1305(w); 1185(m); 1072(ms); 1023(m); 998(ms); 868(s); 736(s); 692(s); 655(vs); 633(s); 465(s). Acknowledgement-We thank Dr. D. M. Adams for recording the Raman spectrum, and the Science Research Council for financial support. Chemistry Department The University Leicester LEl 7RH England
J. inorg, nucl. Chem., 1969, Vol. 31, pp. 3676 to 3680.
R . D . W . KEMMITT V . M . McRAE R.D. PEACOCK I.L. WILSON
Pergamon Press.
Printed in Great Britain
Effect of F- complexing agents on PuF4 dissolution* (First received 24 March 1969; in revised form 8 May 1969) INTRODUCTION INCg~ASING the dissolution of fluoride residues by complexing the fluoride ion is a known procedure. Uranium tetrafiuoride dissolution was increased by boric acid addition[l], and also AI and Ca ions have been used as fluoride complexing agents in uranium solutions [2-4]. Addition of Zr(IV), Fe(III), or AI(III) has been reported to increase plutonium tetraliuoride dissolution[5]. Since aqueous processing of plutonium tetrafluoride in nitric acid requires rapid dissolution for minimum operator exposure to neutron radiation, a study was made of fluoride complexing agents aiding dissolution. Two types of fluoride complexing agents were investigated. The first type, AI(III), B(III), Zr(IV), and sometimes Th(IV), forms soluble complexes with fluoride. The second type, Ca(II), Mg(II), and sometimes Th(IV), forms insoluble compounds. A survey of equilibrium constants of the various fluoride compounds[6] was made and Ca(II), Mg(II), Th(IV) and Zr(IV) were chosen for a comparison against AI(III) and B(III). Table 1 contains the equilibrium constants for the selected agents as well as for plutonium. Although the values were obtained from experimental conditions using different media, they were the only ones available for this general comparison. According to the stability constants, plutonium tetrafluoride dissolution should be increased by metal ions in this order: Th(IV) < Zr(IV) < Al(III) < B(III). The solubility products of resulting fluoride precipitates should be more negative than that of PuF4 to increase dissolution of the latter, and Th(IV) was the most promising ion on this basis. Although Ca(II) and Mg(II) have greater Ksp values than PuF4, both ions were investigated to check the validity of using the Ksp values to compare the effect of precipitating agents on dissolution. *This paper was based on work performed under U.S. Atomic Energy Commission Contract AT(29-1)-1106. 1. 2. 3. 4. 5.
W. M. Wise, H. R. Soehnlin and C. H. McBride, Analyt. Chem. 34, 1035 (1962). R. M. Hainer and E. C. Evers, U.S. Pat. 2,780,532, August 13 (1948). J. W. Gates,Jr. and L. S. Andrews, U.S. Pat. 2,780,518, February 5 (1957). E.J. King and H. M. Clark, U.S. Pat. 2,847,277, August 12 (1958). The Actinide Elements (Edited by G. T. Seaborg and J. J. Katz) National Nuclear Energy Series, Division IV-Plutonium Project Record Volume 14A. McGraw-Hill, New York (1954). 6. L. G. Sillen and A. E. Martell, Stability Constants of Metal-lon Complexes, p. 257. The Chemical Society, London (1964).
Notes
parameters as Dq = 6339 cm-~; F2 = 402 cm-l; F4 = 134 cm -a. Which locates the A~ --* E transition at 30,851 cm-L The experimental value is 23,255 cm-L In aqueous solution the spectra (Fig. 5b) of the pyridine complex is completely different. Outside the charge transfer band there is one absorption peak at 460 m/~(~ = 60) and one at 580 n~(e = 10). It appears that the geometry of the molecule is changed as the crystal goes into solution, but the present data cannot give a definite answer to this problem.
Department of Chemistry University College of Science Calcutta, India
M. BASU S. BASU
J. inorg,nucLChem.,1969,Vol.3I, pp. 3674to 3676. PergamonPress. Printedin GreatBritain
Phosphorus trifluoride complexes of arsenic and antimony pentafluorides (Received 28 April 1969) ALTHOUGH phosphorus trifluoride forms many complexes with transition elements[l] very few complexes are known in which a non-transition element acts as the acceptor. Borine is known to give a 1:1 adduct, PF3. BH312] and higher boranes behave similarly[3,4]. However, phosphorus trifluoride does not form a complex with boron trifluoride, although aluminium trichloride is reported to give an adduct at low temperatures which decomposes at room temperature to aluminium tfifluoride and phosphorus trichloride[5]. Recently the stable compound PF3. B(BF2)3 has also been described[6]. We have now prepared a stable 1:1 adduct between PF3 and antimony pentailuoride and have obtained evidence that a similar adduct exists between PF3 and arsenic pentafluoride at -78 °. Triphenylphosphine and triphenylarsine also form 1 : 1 adducts with antimony pentafluoride. Antimony pentafluoride reacts with phosphorus trifluoride at room temperature to give a I:1 adduct PF3. SbFs. The adduct is a white solid, which is stable in the absence of moisture. Three likely structures can be envisaged for an adduct of this type: (i) a donor-acceptor complex, formed by donation of the lone-pair of electrons on the phosphorus atom, (ii) an ionic complex, PF2 + . SbF6-, (iii) a fluorine-bridged monomer. The i.r. and Raman spectra of the adduct are presented in Table 1. The bands in the region 9001200cm -1 can be assigned to phosphorus-fluorine stretching frequencies. These frequencies are much higher than have previously been observed in any other PF3 complex and are therefore more consistent with structure (ii) rather than structure (i). However, the absorptions in the region 700600 cm -1 are not consistent with a simple SbF6- species (which has a single absorption at 660 cm -1) and both the i.r. and Raman spectra in this region suggest a system of low symmetry. Hence it is possible that in this complex there is cationic-anionic interaction via fluorine bridging as has been observed in the adduct BrF3. SbFs[8]. Phosphorus trifluoride also reacts with arsenic pentafluoride at --78 ° to give a white adduct. The i.r. spectrum of the solid (Table) is similar to that of the antimony pentafluoride adduct and it therefore probably has a similar structure. However, at room temperature it is completely dissociated into its constituents. More stable l : l complexes are obtained from triphenylphosphine and triphenylarsine. These adducts, which are stable for long periods in moist air, are probably simple donor-acceptor complexes containing a direct phosphorus (or arsenic) to antimony bond. 1. T. Kruck, Angew. Chem., Int. Edn. 6, 53 (1967). 2. R.W. Parry and T. C. Bissot, J. Am. chem. Soc. 78, 1524 (1956). 3. J. R. Spielman and A. B. Burg, Inorg. Chem. 2, 1139 (1963). 4. W. R. Deever and D. M. Ritter, J.Am. chem. Soc. 89, 5073 (1967). 5. R. W. Parry, R. C. Taylor, G. Kodama, S. G. Shore, E. Alton, J. R. Weaver, C. E. Nordman and C. Cluff, U.S. Atomic Energy Commission Rep. No. WADC-TR-57-11 (1957); Chem. Abs. 55. 21939 (1961). 6. P. L. Timms,J.Am. chem. Soc. 89, 1629 (1967). 7. R. D. Peacock and D. W. A. Sharp, J. chem. Soc. 2762 (1959). 8. A.J. Edwards and G. R. Jones, Chem. Comm. 1304 (1967).
Notes
3675
Table 1. I.R. (4000-410 cm -1) and Raman spectra PF3* I.R.
892 860
PF3. SbF5 PFa. AsF5 Assignment I.R. Ramani 1.R. 1280w 1155 vw 1080m 970m 695vs 665 sh 620 sh
487 344
1290m 1075ms 915 s 703m 668 s 642m 628 sh 607m
500 sb
va~(P-F) ~s(P-F)
705 vs ~M-F)
500 m
8(PF2)
300 w,br
*M. K. Wilson and S. R. Polo, J. chem. Phys. 20, 1716(1952). t N o bands were observed between 1300-800 c m -1.
EXPERIMENTAL Phosphorus trifluoride was prepared by refluxing phosphorus trichloride with antimony trifluoride. The product gases were led through three -78 ° traps, and were condensed at -183 °. The phosphorus trifluoride was distilled under vacuum at -126" before use. An i.r. spectrum indicated that the product was essentially pure. Arsenic and antimony pentafluorides were prepared by direct fluorination of the elements.
Techniques Standard preparative vacuum-line methods were used throughout. The i.r. spectrum (4000410 cm -~) of the PF3. SbF5 complex was obtained using finely ground solid samples mounted between silver chloride plates. The i.r. spectrum of the PFs. AsF5 adduct was obtained from a solid film of the adduct condensed on a silver chloride plate a t - 7 8 ° under vacuum. The Raman spectrum was obtained on samples held in sealed pyrex tubes. I.r. spectra were recorded on a Perkin-Elmer 225 grating instrument. Raman spectra were recorded on a Cary 81 spectrophotometer fitted with a helium-neon laser. PF3. SbF5 Phosphorus trifluoride gas was condensed onto SbF5 (5 g) held in a 25 mi bulb. The bulb was repeatedly warmed to room temperature and cooled to -196 ° to promote reaction. The preparation was completed by holding liquid PFz (5 ml) over the reaction mixture at --126 ° for several hours. Excess PF3 was then distilled from the system to leave the white solid product. Analysis. Found: F, 50-0; P, 9.8; Sb, 39.8. FsPSb requires F, 51.5; P, 9.9; Sb, 38-7%.
The reaction o f AsF5 with PFz Equal volumes of AsF5 and PF3 were condensed together at --196 °, and warmed to --78 °. A white solid formed at this temperature. As the reaction vessel was slowly warmed to room temperature, the volume of the solid decreased. At room temperature no solid remained. An i.r. spectrum of the residual gases showed only the starting materials to be present. SbFs. P(C6H~)a SbFn. CH3CN (0-5 g) dissolved in acetonitrile (5 ml) was added to a suspension of triphenylphosphine (0-5 g) in acetonitrile (5 ml). After standing at room temperature for 1 hr excess acetonitrile was removed under vacuum to leave the white crystalline product. Analysis. Found: C, 45.1; H, 3.1; F, 19.9; P, 6-2. C18H15F~PSb requires C, 45-1; H, 3"1; F, 19.8; P, 6.5%.
3676
Notes
I.R. spectrum. (2500-400cm-1); 1585(s); 1485(s); 1438(s); 1337(m); 1320(m); 1300(w); 1283(w); 1267(w); l l90(ms); l168(ms); 1098(s); 1073(m); 1028(m); 998(s); 979(m); 735(s); 719(s); 690(s); 650(vs); 624(vs); 525(s); 497(s). SbFs.As(CoHs)a Procedure as above from SbFs. CH3CN (0.42 g) and triphenylarsine (0.5 g). Analysis. Found: C, 41 "2; H, 2.9; F, 17.9; C18H15AsF~Sb requires C, 41-3; H, 2.9; F, 18.2%. I.R. spectrum. (2500-400cm-1); 1715(s); 1575(m); 1480(s); 1438(s); 1335(w); 1305(w); 1185(m); 1072(ms); 1023(m); 998(ms); 868(s); 736(s); 692(s); 655(vs); 633(s); 465(s). Acknowledgement-We thank Dr. D. M. Adams for recording the Raman spectrum, and the Science Research Council for financial support. Chemistry Department The University Leicester LEl 7RH England
J. inorg, nucl. Chem., 1969, Vol. 31, pp. 3676 to 3680.
R . D . W . KEMMITT V . M . McRAE R.D. PEACOCK I.L. WILSON
Pergamon Press.
Printed in Great Britain
Effect of F- complexing agents on PuF4 dissolution* (First received 24 March 1969; in revised form 8 May 1969) INTRODUCTION INCg~ASING the dissolution of fluoride residues by complexing the fluoride ion is a known procedure. Uranium tetrafiuoride dissolution was increased by boric acid addition[l], and also AI and Ca ions have been used as fluoride complexing agents in uranium solutions [2-4]. Addition of Zr(IV), Fe(III), or AI(III) has been reported to increase plutonium tetraliuoride dissolution[5]. Since aqueous processing of plutonium tetrafluoride in nitric acid requires rapid dissolution for minimum operator exposure to neutron radiation, a study was made of fluoride complexing agents aiding dissolution. Two types of fluoride complexing agents were investigated. The first type, AI(III), B(III), Zr(IV), and sometimes Th(IV), forms soluble complexes with fluoride. The second type, Ca(II), Mg(II), and sometimes Th(IV), forms insoluble compounds. A survey of equilibrium constants of the various fluoride compounds[6] was made and Ca(II), Mg(II), Th(IV) and Zr(IV) were chosen for a comparison against AI(III) and B(III). Table 1 contains the equilibrium constants for the selected agents as well as for plutonium. Although the values were obtained from experimental conditions using different media, they were the only ones available for this general comparison. According to the stability constants, plutonium tetrafluoride dissolution should be increased by metal ions in this order: Th(IV) < Zr(IV) < Al(III) < B(III). The solubility products of resulting fluoride precipitates should be more negative than that of PuF4 to increase dissolution of the latter, and Th(IV) was the most promising ion on this basis. Although Ca(II) and Mg(II) have greater Ksp values than PuF4, both ions were investigated to check the validity of using the Ksp values to compare the effect of precipitating agents on dissolution. *This paper was based on work performed under U.S. Atomic Energy Commission Contract AT(29-1)-1106. 1. 2. 3. 4. 5.
W. M. Wise, H. R. Soehnlin and C. H. McBride, Analyt. Chem. 34, 1035 (1962). R. M. Hainer and E. C. Evers, U.S. Pat. 2,780,532, August 13 (1948). J. W. Gates,Jr. and L. S. Andrews, U.S. Pat. 2,780,518, February 5 (1957). E.J. King and H. M. Clark, U.S. Pat. 2,847,277, August 12 (1958). The Actinide Elements (Edited by G. T. Seaborg and J. J. Katz) National Nuclear Energy Series, Division IV-Plutonium Project Record Volume 14A. McGraw-Hill, New York (1954). 6. L. G. Sillen and A. E. Martell, Stability Constants of Metal-lon Complexes, p. 257. The Chemical Society, London (1964).