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A new thorium nitrate hydrate
Notes
3975
J. inorg,nucLChem.,1971,Vol.33, pp. 3975-3976. PergamonPress. Printedin Great Britain
A new thorium nitrate hydrate (Received 1 March 1971) THE Th(NO:~)4-HNO3-H20 system at 25°C[1] and the Th(NOa)4-H20 system as a function of temperature [2] have been described in terms of a variety of solid hydrates of Th(NO3)4 and solutions of unspecified composition. No complete analytical or X-ray data have been published for the majority of the phases reported, although recently the existence of Th(NO3)4 • 5H20 was established unequivocally by single crystal X-ray and neutron diffraction studies[3,4]. We have confirmed the existence of this compound, and wish to report a new thorium nitrate hydrate prepared during a reexamination of this system. As starting materials we have used "AnalaR" thorium tetranitrate hydrates obtained from British Drug Houses or Hopkin & Williams. These have been designated Th(NO3)4-4H20 or Th(NO3)4 • 6H20 by the manufacturers, but analytical and X-ray diffraction measurements show that they are not single phase, and it should be emphasised that no complete description of either the tetrahydrate or the hexahydrate has been published, although both have been reported as single phase materials in previous investigations [ 1,2]. When the starting material was recrystallised from concentrated nitric acid at room temperature, well defined crystals of Th(NO3)4 • 5H._,O were obtained, which gave an X-ray pattern identical with that reported previously [3,5]. [Theoretical: Th, 40.7%; NO.~ , 43•5%. Found: Th, 40-7%; NO3-, 43'4c~,. Th was determined gravimetrically by combustion to ThO2, NO:~ by the Kjeldahl technique]. When a 3.5 molar aqueous solution of this material is left to stand at room temperature over a period of (typically 5-7) days, we find that the first product to crystallise appears as colourless needles with the X-ray powder pattern shown in the Table. It must be pointed out that in most of our experiments mixtures of phases were formed: the phase diagram is obviously extremely complex, and the ranges of stability of the various phases formed in this system are simply not known. Weissenberg and precession photographs of the needles reveal a monoclinic cell with a = 1.76 _+0.01, b = 1-65 _+0.01. c = 2.42 +_0.01 nm,/3 = 88.5 _+_0-1 °. Part of the powder diffraction pattern has been indexed accordingly in Table 1. Analysis of this material shows, typically: Th, 36.0%; NO:~ . 54.7%; NO:C/Th = 5"7; the density determined by CCI4 displacement is 2.46 g cm -:~. These results are in reasonable agreement with the formula: H2Th(NO~)6- 3H_,O. [Theoretical: Th, 35.2%; NO:~ , 56.4%; p (16 formula units/cell) = 2.50g cm :~.] On heating in air to 55-60°C. or pumping at room temperature, a weight loss of 8 per cent is observed, corresponding closely to the loss of three water molecules; this is regained when the material is allowed to stand again in air at room temperature. The species H..,Th(NOa)~ was postulated by Ryan[6] when discussing the complex nitrates of Th, Np and Pu. The basic nitrates Th(OH).,(NO3)2 • xH20 and Th(OH)(NOa)3 • 4H~O have been positively identified by Johansson [7] who reports that both are extremely water soluble, but hitherto there has been no reported observation of an acid nitrate of thorium. It must be noted, however, that the analytical results show some variation from batch to batch (NO:~-/Th = 5.5-5•8). The explanation for this is most probably contamination by a second phase: some X-ray powder photographs have indeed shown the presence of Th(NO3L" 5H20. Whereas individual needles may be picked out for single crystal X-ray measurements, it is more difficult to exclude possible contaminants from the larger samples required for chemical analysis and powder diffraction work. It is also possible that the true formulation may be Th(NO:04 " 5-xH20 • xHNO:~, in I. J. R. Ferraro, L. I. Katzin and G. G i b s o n , J . A m . Chem. Soc. 76,909 (1954)• 2. W. L. Marshall, J. S. Gill and C. H. Secoy, J. A m. Chem. Soc. 73.4991 (1951). 3. T. Ueki, A. Zalkin and D. H. Templeton, A cta crystallogr 20,836 (1966). 4..1. C. Taylor. M. H. Mueller and R. L. Hitterman. A cta crystallogr 20,842 (1966). 5. E. Staritzky,Analyt. Chem. 28, 2021 (1956). 6. J. L. Ryan, J. phys. Chem. 64, 1375 (1960). 7. G. Johansson. Svensk Kemish Tidskrift 78,486 (1966).
3976
Notes Table 1
hkl 012 200 020 10-3 12-1 21-2 004 301 311 032 024 13-2 401 410 040 016 420 043 242 501 510 107
Sin20 (calc.)
Sin20 (obs.)*
/ (obs.)
0.0061 0.0075 0.0086 0.0110 0.0116 0.0140 0.0160 0.0180 0.0202 0.0236 0.0248 0.0256 0.0315 0"0328 0.0348 0.0385 0.0394 0.0440 0-0464 0.0488 0.0502 0.0511
0.0062 0"0075 0.0086 0-0110 0.0116 0"0138 0"0161 0.0180 0"0203 0.0235 0.0248 0.0256 0.0313 0"0328 0"0348 0-0385 0"0393 0.0440 0-0464 0.0489 0.0503 0.0511
M W M W M VS VS W W W VS W S S W S M W VS M S M
*Nonius focussing powder camera; CuK~ radiation, X = 0.15405 rim. which part of the water of crystallisation is replaced by nitric acid. A structure determination is under way, using single crystal X-ray diffraction techniques, in order to establish the detailed positions of the NO3- and H20 groups. Further work is necessary to prove the existence of other compounds in this system: thermal decomposition studies on Th(NO3)4 • 5H20 have yielded results which are in excellent agreement with those of Claudel [8], suggesting the formation of Th(NO3)4 • 4H20 and Th(NO3)4 • 3H20 on both the TGA and DTA curves, but we have not yet been able to isolate and identify these two phases unequivocally.
Applied Chemistry Division, A.E.R.E., Harwell, Didcot, Berks, England
P . T . MOSELEY S.W. SANDERSON V.J. WHEELER
8. B. Claudel, Thesis, University of Lyon, France (1962). P. Bussirre, B. Claudel, J. P. Renouf, Y. Trambouze and M. Prettre, J. chim. Phys. 58, 668 (1961). J. inorg,nucl.Chem.,197I, Vol.33, pp. 3976-3978. PergamonPress. Printedin Great Britain
Ionic-strength independence of the vanadium(V)-iodide reaction rate, and the structure of aqueous vanadium(V) (Received 10 March 1971) A VARIETY of configurations for vanadium(V) in acidic aqueous solution has been proposed (for
3975
J. inorg,nucLChem.,1971,Vol.33, pp. 3975-3976. PergamonPress. Printedin Great Britain
A new thorium nitrate hydrate (Received 1 March 1971) THE Th(NO:~)4-HNO3-H20 system at 25°C[1] and the Th(NOa)4-H20 system as a function of temperature [2] have been described in terms of a variety of solid hydrates of Th(NO3)4 and solutions of unspecified composition. No complete analytical or X-ray data have been published for the majority of the phases reported, although recently the existence of Th(NO3)4 • 5H20 was established unequivocally by single crystal X-ray and neutron diffraction studies[3,4]. We have confirmed the existence of this compound, and wish to report a new thorium nitrate hydrate prepared during a reexamination of this system. As starting materials we have used "AnalaR" thorium tetranitrate hydrates obtained from British Drug Houses or Hopkin & Williams. These have been designated Th(NO3)4-4H20 or Th(NO3)4 • 6H20 by the manufacturers, but analytical and X-ray diffraction measurements show that they are not single phase, and it should be emphasised that no complete description of either the tetrahydrate or the hexahydrate has been published, although both have been reported as single phase materials in previous investigations [ 1,2]. When the starting material was recrystallised from concentrated nitric acid at room temperature, well defined crystals of Th(NO3)4 • 5H._,O were obtained, which gave an X-ray pattern identical with that reported previously [3,5]. [Theoretical: Th, 40.7%; NO.~ , 43•5%. Found: Th, 40-7%; NO3-, 43'4c~,. Th was determined gravimetrically by combustion to ThO2, NO:~ by the Kjeldahl technique]. When a 3.5 molar aqueous solution of this material is left to stand at room temperature over a period of (typically 5-7) days, we find that the first product to crystallise appears as colourless needles with the X-ray powder pattern shown in the Table. It must be pointed out that in most of our experiments mixtures of phases were formed: the phase diagram is obviously extremely complex, and the ranges of stability of the various phases formed in this system are simply not known. Weissenberg and precession photographs of the needles reveal a monoclinic cell with a = 1.76 _+0.01, b = 1-65 _+0.01. c = 2.42 +_0.01 nm,/3 = 88.5 _+_0-1 °. Part of the powder diffraction pattern has been indexed accordingly in Table 1. Analysis of this material shows, typically: Th, 36.0%; NO:~ . 54.7%; NO:C/Th = 5"7; the density determined by CCI4 displacement is 2.46 g cm -:~. These results are in reasonable agreement with the formula: H2Th(NO~)6- 3H_,O. [Theoretical: Th, 35.2%; NO:~ , 56.4%; p (16 formula units/cell) = 2.50g cm :~.] On heating in air to 55-60°C. or pumping at room temperature, a weight loss of 8 per cent is observed, corresponding closely to the loss of three water molecules; this is regained when the material is allowed to stand again in air at room temperature. The species H..,Th(NOa)~ was postulated by Ryan[6] when discussing the complex nitrates of Th, Np and Pu. The basic nitrates Th(OH).,(NO3)2 • xH20 and Th(OH)(NOa)3 • 4H~O have been positively identified by Johansson [7] who reports that both are extremely water soluble, but hitherto there has been no reported observation of an acid nitrate of thorium. It must be noted, however, that the analytical results show some variation from batch to batch (NO:~-/Th = 5.5-5•8). The explanation for this is most probably contamination by a second phase: some X-ray powder photographs have indeed shown the presence of Th(NO3L" 5H20. Whereas individual needles may be picked out for single crystal X-ray measurements, it is more difficult to exclude possible contaminants from the larger samples required for chemical analysis and powder diffraction work. It is also possible that the true formulation may be Th(NO:04 " 5-xH20 • xHNO:~, in I. J. R. Ferraro, L. I. Katzin and G. G i b s o n , J . A m . Chem. Soc. 76,909 (1954)• 2. W. L. Marshall, J. S. Gill and C. H. Secoy, J. A m. Chem. Soc. 73.4991 (1951). 3. T. Ueki, A. Zalkin and D. H. Templeton, A cta crystallogr 20,836 (1966). 4..1. C. Taylor. M. H. Mueller and R. L. Hitterman. A cta crystallogr 20,842 (1966). 5. E. Staritzky,Analyt. Chem. 28, 2021 (1956). 6. J. L. Ryan, J. phys. Chem. 64, 1375 (1960). 7. G. Johansson. Svensk Kemish Tidskrift 78,486 (1966).
3976
Notes Table 1
hkl 012 200 020 10-3 12-1 21-2 004 301 311 032 024 13-2 401 410 040 016 420 043 242 501 510 107
Sin20 (calc.)
Sin20 (obs.)*
/ (obs.)
0.0061 0.0075 0.0086 0.0110 0.0116 0.0140 0.0160 0.0180 0.0202 0.0236 0.0248 0.0256 0.0315 0"0328 0.0348 0.0385 0.0394 0.0440 0-0464 0.0488 0.0502 0.0511
0.0062 0"0075 0.0086 0-0110 0.0116 0"0138 0"0161 0.0180 0"0203 0.0235 0.0248 0.0256 0.0313 0"0328 0"0348 0-0385 0"0393 0.0440 0-0464 0.0489 0.0503 0.0511
M W M W M VS VS W W W VS W S S W S M W VS M S M
*Nonius focussing powder camera; CuK~ radiation, X = 0.15405 rim. which part of the water of crystallisation is replaced by nitric acid. A structure determination is under way, using single crystal X-ray diffraction techniques, in order to establish the detailed positions of the NO3- and H20 groups. Further work is necessary to prove the existence of other compounds in this system: thermal decomposition studies on Th(NO3)4 • 5H20 have yielded results which are in excellent agreement with those of Claudel [8], suggesting the formation of Th(NO3)4 • 4H20 and Th(NO3)4 • 3H20 on both the TGA and DTA curves, but we have not yet been able to isolate and identify these two phases unequivocally.
Applied Chemistry Division, A.E.R.E., Harwell, Didcot, Berks, England
P . T . MOSELEY S.W. SANDERSON V.J. WHEELER
8. B. Claudel, Thesis, University of Lyon, France (1962). P. Bussirre, B. Claudel, J. P. Renouf, Y. Trambouze and M. Prettre, J. chim. Phys. 58, 668 (1961). J. inorg,nucl.Chem.,197I, Vol.33, pp. 3976-3978. PergamonPress. Printedin Great Britain
Ionic-strength independence of the vanadium(V)-iodide reaction rate, and the structure of aqueous vanadium(V) (Received 10 March 1971) A VARIETY of configurations for vanadium(V) in acidic aqueous solution has been proposed (for