- Email: [email protected]
Graphite intercalation compounds with xenon oxide tetrafluoride and iodine pentafluoride
INORG.
NUCL. CHEM. LETTERS VoL 11, pp. 75-77,
1975. Pergamon Press. Printed in Great Britain.
GRAPHITE INTERCALATION COMPOUNDS WITH XENON OXIDE TETRAFLUORIDE AND IODINE PENTAFLUORIDE
Henry Selig and Oren Gani Department of Inorganic & Analytical Chemistry Hebrew University, Jerusalem, Israel ~ e c e ~ e d 7 0 c ~ b e r 1974)
Layer
compounds of graphite
with
have been known for many years (1,2).
many d i f f e r e n t
inorganic
substances
More recently, a number of graphite
intercalation compounds with inorganic fluorides have been described (3-5). Particularly to be noted (4) are compounds with halogen fluorides of reported stoichiometries C8.9BrF 3 and CI8IF5 .
The close similarities of the chemical
and physical properties of iodine pentafluoride and xenon oxide tetrafluoride (6), prompted us to attempt to prepare graphite intercalation compounds with XeOF 4 • Xenon oxide tetrafluoride forms such a compound with stoichiometry of about Cs.7XeOF 4.
The material retains the black, glossy appearance of the
original graphite, although it contains as much as 68% by weight of XeOF 4. The compound is stable at 0 °, but decomposes slowly above room temperature liberating mostly XeOF4, but in addition minor amounts of xenon gas.
At still
higher temperatures somewhat larger amounts of xenon are released, but up to i00 ° only about half the originally incorporated xenon is liberated as either XeOF 4 or the element.
At i00 ° neither XeOF 4 nor CO 2 is liberated.
No non-
condensible gases are released at any time, indicating that XeOF 4 may oxy-
75
76
GRAPHITE INTERCALATION COMPOUNDS
Vol. 11, No. 1
fluorinate the graphite at higher temperatures. The XeOF4, when incorporated into the graphite, is much more resistant to h)rdrolysis. Fluorine analysis of an aqueous solution in contact with the graphite compound shows only a slow increase of fluorine concentration with time.
On the other hand, addition of a reducing agent such as acidified KI
solution greatly shortens the degradation time of the bound XeOF 4.
However,
even after several days not all of the xenon has been reduced. Preliminary tests indicate that the intercalated XeOF 4 behaves much more mildly towards easily oxidized organic substances than the free oxyfluoride. It thus promises to be useful as a simple, easily handled fluorinating agent. Caution is advised, however, as in at least one case an explosion occurred upon addition of a KI solution to half a gram of the material. Parallel experiments were carried out with iodine pentafluoride, and stoichiometries of about C8.5IF 5 were obtained.
Elemental analysis of this
compound gave an F:I ratio of 5:1 after extraction of the compound with 5% NaOH.
The compound begins to decompose around 80 ° with liberation of IF 5 in
agreement with earlier work (4). However, our results indicate that earlier workers (4) must have had incomplete reaction as their reported stoichiometry was CI8IFs.
The similarity in stoichiometries of the compounds with IF S and
Xe0F 4 is expected on the basis of their analogous molecular shapes and dimensions. X-ray patterns of the intercalation compounds obtained with copper radiation show an almost complete absence of the original strong graphite line with d = 3.35~ and the appearance of a new pattern (for C8.5IF5: spacings of 6.15s, 3.72vs, 2.96 and 2.87~; for C8.7XeOF4 : 5.72s, 3.87 and 2.82~).
d-
d-spacings of
After hydrolysis of the intercalates and drying of the
residues, the original graphite pattern was again obtained from the IF5 intercalate and from the XeOF 4 compound a broad peak with d = 3.63~ was obtained, the latter apparently still showing a partly expanded graphite lattice.
Vol. 11, No. 1
GRAPHITE INTERCALATION COMPOUNDS
77
Experimental Graphite was obtained either as native powder from BDH or as "Grafoil" from the Union Carbide Corp.
in the form of sheets.
~i nun squares which were expanded by alternately
The latter was cut into
immersing in liquid nitrogen
and heating with a very hot air stream from a Heat Gun. the expanded Grafoil was about 37 m2/gm, the powder. cedure
The surface area of
compared with a value of 6 m2/gm for
The native powder was cleaned by a previously designated pro-
(7) while the Grafoil was sufficiently pure as received.
Reactions were
carried out in 3/4" KeI-F tubes sealed with 1/4" flare KeI-F valves by adding a large excess of liquid XeOF 4 or IF 5 to the preweighed graphite and allowing to contact at room temperature pumped off with intermittent stant weight.
for 24 hours.
The excess reagent was then
weighing until the reaction vessel attained con-
With Xe0F 4 this was reached at o ° after 6-8 hours and with IF 5
after 4-6 hours at room temperature depending on the initial amount used. Subsequent manipulations
were carried out under dry nitrogen in a dry box.
Four separate experiments 8.68, respectively. and 9.8. variations
Experiments
The differences
gave CnXe0F 4 with n = 8.55, 8.82, 8.75 and with IF 5 gave CnIF 5 with n = 8.0, 8.5, 8.4
are probably significant and may depend on slight
in particle size.
References i.
G.R. HENNIG,
2.
R.C. CROFT, Austral.
3.
A.A. OPALEVSKII, 17, 1366
4.
"Progress
(1972).
A.A. OPALEVSKII, l!, 1227
in Inorganic Chemistry," ~, 125
(1959).
J. Chem., 9, 201 (1956).
A.S. NAZAROV and A.A. UMINSKII,
Russ. J. Inorg. Chem.,
Engl. transl. A.S. NAZAROV, A.A. UMINSKII and Yu.V. CIIICAGOV,
ibid.,
(1972).
5.
J.M. LALANCETTE and J. LAFONTAINE,
6.
M.C. W A L D ~ N
7.
A.A. OPALEVSKII,
632 (1972).
Chem. Comm.,
81S (1973).
and H. SELIG, J. Inorg. Nucl. Chem., 35, 2173 (1973)~ A.S. NAZAROV and A.A. UMINSKII,
Russ. J. Inorg. Chem.,
17
NUCL. CHEM. LETTERS VoL 11, pp. 75-77,
1975. Pergamon Press. Printed in Great Britain.
GRAPHITE INTERCALATION COMPOUNDS WITH XENON OXIDE TETRAFLUORIDE AND IODINE PENTAFLUORIDE
Henry Selig and Oren Gani Department of Inorganic & Analytical Chemistry Hebrew University, Jerusalem, Israel ~ e c e ~ e d 7 0 c ~ b e r 1974)
Layer
compounds of graphite
with
have been known for many years (1,2).
many d i f f e r e n t
inorganic
substances
More recently, a number of graphite
intercalation compounds with inorganic fluorides have been described (3-5). Particularly to be noted (4) are compounds with halogen fluorides of reported stoichiometries C8.9BrF 3 and CI8IF5 .
The close similarities of the chemical
and physical properties of iodine pentafluoride and xenon oxide tetrafluoride (6), prompted us to attempt to prepare graphite intercalation compounds with XeOF 4 • Xenon oxide tetrafluoride forms such a compound with stoichiometry of about Cs.7XeOF 4.
The material retains the black, glossy appearance of the
original graphite, although it contains as much as 68% by weight of XeOF 4. The compound is stable at 0 °, but decomposes slowly above room temperature liberating mostly XeOF4, but in addition minor amounts of xenon gas.
At still
higher temperatures somewhat larger amounts of xenon are released, but up to i00 ° only about half the originally incorporated xenon is liberated as either XeOF 4 or the element.
At i00 ° neither XeOF 4 nor CO 2 is liberated.
No non-
condensible gases are released at any time, indicating that XeOF 4 may oxy-
75
76
GRAPHITE INTERCALATION COMPOUNDS
Vol. 11, No. 1
fluorinate the graphite at higher temperatures. The XeOF4, when incorporated into the graphite, is much more resistant to h)rdrolysis. Fluorine analysis of an aqueous solution in contact with the graphite compound shows only a slow increase of fluorine concentration with time.
On the other hand, addition of a reducing agent such as acidified KI
solution greatly shortens the degradation time of the bound XeOF 4.
However,
even after several days not all of the xenon has been reduced. Preliminary tests indicate that the intercalated XeOF 4 behaves much more mildly towards easily oxidized organic substances than the free oxyfluoride. It thus promises to be useful as a simple, easily handled fluorinating agent. Caution is advised, however, as in at least one case an explosion occurred upon addition of a KI solution to half a gram of the material. Parallel experiments were carried out with iodine pentafluoride, and stoichiometries of about C8.5IF 5 were obtained.
Elemental analysis of this
compound gave an F:I ratio of 5:1 after extraction of the compound with 5% NaOH.
The compound begins to decompose around 80 ° with liberation of IF 5 in
agreement with earlier work (4). However, our results indicate that earlier workers (4) must have had incomplete reaction as their reported stoichiometry was CI8IFs.
The similarity in stoichiometries of the compounds with IF S and
Xe0F 4 is expected on the basis of their analogous molecular shapes and dimensions. X-ray patterns of the intercalation compounds obtained with copper radiation show an almost complete absence of the original strong graphite line with d = 3.35~ and the appearance of a new pattern (for C8.5IF5: spacings of 6.15s, 3.72vs, 2.96 and 2.87~; for C8.7XeOF4 : 5.72s, 3.87 and 2.82~).
d-
d-spacings of
After hydrolysis of the intercalates and drying of the
residues, the original graphite pattern was again obtained from the IF5 intercalate and from the XeOF 4 compound a broad peak with d = 3.63~ was obtained, the latter apparently still showing a partly expanded graphite lattice.
Vol. 11, No. 1
GRAPHITE INTERCALATION COMPOUNDS
77
Experimental Graphite was obtained either as native powder from BDH or as "Grafoil" from the Union Carbide Corp.
in the form of sheets.
~i nun squares which were expanded by alternately
The latter was cut into
immersing in liquid nitrogen
and heating with a very hot air stream from a Heat Gun. the expanded Grafoil was about 37 m2/gm, the powder. cedure
The surface area of
compared with a value of 6 m2/gm for
The native powder was cleaned by a previously designated pro-
(7) while the Grafoil was sufficiently pure as received.
Reactions were
carried out in 3/4" KeI-F tubes sealed with 1/4" flare KeI-F valves by adding a large excess of liquid XeOF 4 or IF 5 to the preweighed graphite and allowing to contact at room temperature pumped off with intermittent stant weight.
for 24 hours.
The excess reagent was then
weighing until the reaction vessel attained con-
With Xe0F 4 this was reached at o ° after 6-8 hours and with IF 5
after 4-6 hours at room temperature depending on the initial amount used. Subsequent manipulations
were carried out under dry nitrogen in a dry box.
Four separate experiments 8.68, respectively. and 9.8. variations
Experiments
The differences
gave CnXe0F 4 with n = 8.55, 8.82, 8.75 and with IF 5 gave CnIF 5 with n = 8.0, 8.5, 8.4
are probably significant and may depend on slight
in particle size.
References i.
G.R. HENNIG,
2.
R.C. CROFT, Austral.
3.
A.A. OPALEVSKII, 17, 1366
4.
"Progress
(1972).
A.A. OPALEVSKII, l!, 1227
in Inorganic Chemistry," ~, 125
(1959).
J. Chem., 9, 201 (1956).
A.S. NAZAROV and A.A. UMINSKII,
Russ. J. Inorg. Chem.,
Engl. transl. A.S. NAZAROV, A.A. UMINSKII and Yu.V. CIIICAGOV,
ibid.,
(1972).
5.
J.M. LALANCETTE and J. LAFONTAINE,
6.
M.C. W A L D ~ N
7.
A.A. OPALEVSKII,
632 (1972).
Chem. Comm.,
81S (1973).
and H. SELIG, J. Inorg. Nucl. Chem., 35, 2173 (1973)~ A.S. NAZAROV and A.A. UMINSKII,
Russ. J. Inorg. Chem.,
17