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Graphite lamellar compounds with uranium pentabromide
INORG. NUCL. CHEM. LETTERS Vol. 14, pp. 217-218. © P e r g a m o n Press Ltd. 1978. Printed in Great Britain
GRAPHITE
LAMELLAR
COMPOUNDS
WITH
0020-1650/78/0701-0217502.00/0
URANIUM
PENTABROMIDE
E- Stumpp and R. Niess Anorganisch-chemisches I n s t i t u t der Technischen Universit~t D-3392 Clausthal-Zellerfeld, Federal Republic of Germany
(Received
3
April 1978; received for publication 28 April 1978)
The study of metal chloride intercalation compounds of graphite has made considerable progress in the past years (1,2). By comparison only few metal bromide graphite compounds have been reported until now (3,4,5). As part of a study of intercalation of metal bromides we have investigated the system UBr5/Br2/graphite. The analogous compounds with UCI5 have been long known (6,7) and the existence of an intercalate of UF6 has been confirmed recently (8).
Experimental A natural graphite (NFL 93/95 from Graphitwerk KropfmUhl, MUnchen) of particle size 0.10-0.15 mm was used. I t was purified by hydrochloric and hydrofluoric acid treatment. UBr5 was prepared by the procedure of Lux et al. (9). In a Soxhlet apparatus turnings of uranium metal were heated with bromine. Simultaneously the UBr5 formed was extracted by bromine. After cooling the UBr5 crystallized out and was removed by f i l t r a t i o n . Since UBr5 is very moisture-sensitive all manipulations were carried out in dry nitrogen. Attempts to prepare UBr5-graphite by treating graphite with UBr5 in refluxing bromine, by analogy with the preparation of TIBr3-graphite (10), were unsuccessful. Positive results were obtained by heating UBr5, bromine, and graphite in bomb tubes. The products were washed with acetone to remove the excess of unchanged UBr5. For analysis the samples were burned in a stream of oxygen saturated with water vapour. The bromine and HBr evolved were absorbed in NaOH/Na2SO3 solution. Bromine was determined by argentometric t i t r a t i o n with potentiometric endpoint detection. The amount of uranium was calculated from the weight of the residual U308. The compounds were examined by X-ray powder technique using counter tube registration.
Results and Discussion Compounds with maximum amount of intercalated UBr5 were obtained by heating up to 300°C for 5 days. The compound which was richest in UBr5 had the composition C38UBr5.1. At 450°C the compound C58UBr4. 7 was obtained. Below 300°C the UBr5 content decreased whereas the amount of co-intercalated bromine increased.
217
218
Graphite Lamellar Compounds with Uranium Pentabromide
The compound C38UBr5.1 resembles C37UC15 which was prepared by heating UCl5 with graphite (6). This UCl5-graphite has a structure of the second stage type in which every second layer space of the graphite lattice is f i l l e d with UCl5. As X-ray studies confirmed C38UBr5.1 is also a second stage intercalation compound. The observed 004 reflections and d-spacings (in brackets) are: 002 (656 pm), 003 (438 pm), 004 (335 pm), 005 (276 pm), 008 (166 pm). The repeat distance along the c-axis was calculated to be I c = 1328 pm. Similar values are reported for other second stages of metal bromide intercalates (2). The spacings of carbon planes which have UBr5 layers between them is therefore 1328 - 335 = 993 pm. The exact structure of UBr5 has not yet been established, but i t is reported that i t resembles that of ~-PaBr5 (11). By analogy with intercalated Mo2Cllo (12), we assume that UBr5 is inserted in form of sheets made up of U2Brlo units in which two uranium atoms occupy adjacent octahedra] sites formed by supperposition of two quasi close-packed anion layers containing five bromine atoms each. The thickness of such close-packed bromine layers is compatible with the observed carbon layer spacings containing UBr5. The X-ray patterns of almost all samples showed some reflections in addition to those of the 2nd stage. They could be assigned to a 3rd stage structure with I c = 1645 pm. Acknowledgement
-
This work was supported by the Deutsche Forschungsgemeinschaft.
References 1.
Proceedings of the Franco American Conference on Intercalation Compounds of Graphite, held at La Napoule, France, May 23 to 27, 1977. Ed. F.L. Vogel and A. Herold, Elsevier Sequoia S.A. Lausanne, 1977
2.
E. Stumpp, Mater. Sci. Eng. 3_[I, 53 (1977
3.
T. Sasa, Y. Takahashi and T. Mukaibo, Bull. Chem. Soc. Jpn. 45,
4.
C. Balesteri, R. Vangelisti, J. Melin and A. Herold,
5.
H. Stahl,
6.
W. RUdorff, E. Stumpp, W. Spriessler and F.W. Siecke, Angew. Chem. 7__55, 130 (1963)
7.
A. Boeck and W. RUdorff,
8.
J. Binenboym, H. Selig and S. Sarig,
9.
F. Lux, G. Wirth and K.W. Bagnall,
2250 (1972)
C. R. Hebd. Seances Acad. Sci., Ser. C 279, 279 (1974)
Z. Anorg. Allg. Chem. 428, 269 (1977)
Z. Anorg. Allg. Chem. 397, 179 (1973) J. Inorg. Nucl. Chem. 38, Chem. Bet.
2313 (1976)
103, 2807 (1970)
10. R. Niess and E. Stumpp, Carbon, in press 11. D. Brown,
In Lanthanides and Actinides, Inorg. Chem. Series I, VO]. i, p. 94,
Butterworth's, London (1972) 12. A.W.S. Johnson, Acta Crystallogr.
2_33, 770 (1967)
GRAPHITE
LAMELLAR
COMPOUNDS
WITH
0020-1650/78/0701-0217502.00/0
URANIUM
PENTABROMIDE
E- Stumpp and R. Niess Anorganisch-chemisches I n s t i t u t der Technischen Universit~t D-3392 Clausthal-Zellerfeld, Federal Republic of Germany
(Received
3
April 1978; received for publication 28 April 1978)
The study of metal chloride intercalation compounds of graphite has made considerable progress in the past years (1,2). By comparison only few metal bromide graphite compounds have been reported until now (3,4,5). As part of a study of intercalation of metal bromides we have investigated the system UBr5/Br2/graphite. The analogous compounds with UCI5 have been long known (6,7) and the existence of an intercalate of UF6 has been confirmed recently (8).
Experimental A natural graphite (NFL 93/95 from Graphitwerk KropfmUhl, MUnchen) of particle size 0.10-0.15 mm was used. I t was purified by hydrochloric and hydrofluoric acid treatment. UBr5 was prepared by the procedure of Lux et al. (9). In a Soxhlet apparatus turnings of uranium metal were heated with bromine. Simultaneously the UBr5 formed was extracted by bromine. After cooling the UBr5 crystallized out and was removed by f i l t r a t i o n . Since UBr5 is very moisture-sensitive all manipulations were carried out in dry nitrogen. Attempts to prepare UBr5-graphite by treating graphite with UBr5 in refluxing bromine, by analogy with the preparation of TIBr3-graphite (10), were unsuccessful. Positive results were obtained by heating UBr5, bromine, and graphite in bomb tubes. The products were washed with acetone to remove the excess of unchanged UBr5. For analysis the samples were burned in a stream of oxygen saturated with water vapour. The bromine and HBr evolved were absorbed in NaOH/Na2SO3 solution. Bromine was determined by argentometric t i t r a t i o n with potentiometric endpoint detection. The amount of uranium was calculated from the weight of the residual U308. The compounds were examined by X-ray powder technique using counter tube registration.
Results and Discussion Compounds with maximum amount of intercalated UBr5 were obtained by heating up to 300°C for 5 days. The compound which was richest in UBr5 had the composition C38UBr5.1. At 450°C the compound C58UBr4. 7 was obtained. Below 300°C the UBr5 content decreased whereas the amount of co-intercalated bromine increased.
217
218
Graphite Lamellar Compounds with Uranium Pentabromide
The compound C38UBr5.1 resembles C37UC15 which was prepared by heating UCl5 with graphite (6). This UCl5-graphite has a structure of the second stage type in which every second layer space of the graphite lattice is f i l l e d with UCl5. As X-ray studies confirmed C38UBr5.1 is also a second stage intercalation compound. The observed 004 reflections and d-spacings (in brackets) are: 002 (656 pm), 003 (438 pm), 004 (335 pm), 005 (276 pm), 008 (166 pm). The repeat distance along the c-axis was calculated to be I c = 1328 pm. Similar values are reported for other second stages of metal bromide intercalates (2). The spacings of carbon planes which have UBr5 layers between them is therefore 1328 - 335 = 993 pm. The exact structure of UBr5 has not yet been established, but i t is reported that i t resembles that of ~-PaBr5 (11). By analogy with intercalated Mo2Cllo (12), we assume that UBr5 is inserted in form of sheets made up of U2Brlo units in which two uranium atoms occupy adjacent octahedra] sites formed by supperposition of two quasi close-packed anion layers containing five bromine atoms each. The thickness of such close-packed bromine layers is compatible with the observed carbon layer spacings containing UBr5. The X-ray patterns of almost all samples showed some reflections in addition to those of the 2nd stage. They could be assigned to a 3rd stage structure with I c = 1645 pm. Acknowledgement
-
This work was supported by the Deutsche Forschungsgemeinschaft.
References 1.
Proceedings of the Franco American Conference on Intercalation Compounds of Graphite, held at La Napoule, France, May 23 to 27, 1977. Ed. F.L. Vogel and A. Herold, Elsevier Sequoia S.A. Lausanne, 1977
2.
E. Stumpp, Mater. Sci. Eng. 3_[I, 53 (1977
3.
T. Sasa, Y. Takahashi and T. Mukaibo, Bull. Chem. Soc. Jpn. 45,
4.
C. Balesteri, R. Vangelisti, J. Melin and A. Herold,
5.
H. Stahl,
6.
W. RUdorff, E. Stumpp, W. Spriessler and F.W. Siecke, Angew. Chem. 7__55, 130 (1963)
7.
A. Boeck and W. RUdorff,
8.
J. Binenboym, H. Selig and S. Sarig,
9.
F. Lux, G. Wirth and K.W. Bagnall,
2250 (1972)
C. R. Hebd. Seances Acad. Sci., Ser. C 279, 279 (1974)
Z. Anorg. Allg. Chem. 428, 269 (1977)
Z. Anorg. Allg. Chem. 397, 179 (1973) J. Inorg. Nucl. Chem. 38, Chem. Bet.
2313 (1976)
103, 2807 (1970)
10. R. Niess and E. Stumpp, Carbon, in press 11. D. Brown,
In Lanthanides and Actinides, Inorg. Chem. Series I, VO]. i, p. 94,
Butterworth's, London (1972) 12. A.W.S. Johnson, Acta Crystallogr.
2_33, 770 (1967)