COMPLEXING BETWEEN ORTHOPERIODIC ACID AND PERIODATE ION
1695
other phases have not been found here. Nitric acid sub-
Found, wt %: I, 43.2; Cs, 22.5.
stantially increases the solubility of CsIO , because the
4
The complex was stable under ambient standard
conditions in a dry atmosphere. When its crystals were
heated in a sealed glass capillary, their edges were
stronger nitric acid replaces periodic acid in the salt,
which is solubilized as orthoperiodate.
First, we carried out tentative experiments as fol- rounded at 47–50°ë. Further heating up to 90°ë did
lows. Variable amounts of CsNO and H IO were dis- not induce melting. Cs[H IO · H IO ] was extremely
3
5
6
4
6
5
6
solved in nitric acid of a certain concentration. Then, hygroscopic; in contact with a moist atmosphere, it
the solution was allowed to concentrate at room tem- rather rapidly transformed to the aquated complex
perature, and the crystallographic composition of the Cs[H IO · H IO · 0.5H O].
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6
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6
2
solid was determined at various concentration stages
using powder X-ray diffraction. In this way, we eluci-
In vacuo at room temperature, both complexes lost
their water and transformed to a CsIO + H IO mix-
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6
dated that CsIO only separated from the solution when
4
ture. X-ray diffraction data for the samples synthesized
are displayed in the table. They coincide with the pat-
terns simulated from single-crystal X-ray diffraction
data [7].
the HNO concentration was lower than 10%. At higher
3
nitric acid concentrations, the solid that resulted from
solvent evaporation also contained the aquated com-
plex Cs[H IO · H IO · 0.5H O]. From the solution con-
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2
taining 15–25% nitric acid, only the specified complex
2
CsNO · HNO · H IO Synthesis
3 3 5 6
crystallized without a CsIO admixture. When the acid
4
concentration was higher than 25%, the anhydrous
At room temperature, in 56% nitric acid (10 g,
complex Cs[H IO · H IO ] appeared in the solid phase. 88.9 mmol) dissolved were CsNO (5.77 g, 29.6 mmol)
4
6
5
6
3
From highly concentrated (56%) HNO , one more com- and H IO (3.38 g, 14.8 mmol). The molar ratio was
3
5
6
plex crystallized containing nitrate in addition to perio- CsNO : HNO : H IO = 2 : 6 : 1. The mixture was
3
3
5
6
date. Subsequent work consisted in the determination
of optimal conditions for preparing the above-listed
complexes and their characterization.
allowed to stand at +5°ë in a vacuum desiccator with
CaCl as a dryer and ascarite as an absorbent of nitric
2
acid vapor. After one day, 2CsNO · HNO · H IO crys-
3
3
5
6
tals appeared from the solution. We found that the same
complex can be obtained by simply mixing stoichio-
metric amounts of crystalline CsNO and H IO with
Cs[H IO · H IO · 0.5H O] Synthesis
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6
2
3
5
6
At room temperature, in 19% HNO3 (8 g,
4.44 mmol) dissolved were H IO (6.08 g, 26.68 mmol)
liquid 100% HNO . One to two hours after mixing,
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2
5
6
pieces of a solid product were powdered with a mortar
and pestle. The X-ray diffraction patterns of this pow-
der and the aforementioned crystals that were obtained
from strong nitric acid fully coincided (table). The
product was very hygroscopic and reactive. It reacted
with Nujol, KBr, NaCl, and CsCl; therefore, we failed
to record its IR spectrum. The Raman spectrum of the
and CsNO (1.78 g, 9.13 mmol). The molar ratio was
3
CsNO : HNO : H IO = 1.0 : 2.7 : 2.9. After the solu-
3
3
5
6
tion was allowed to stand for 24 h at –10…–12°ë, large
clear crystals (~2 g) separated from the solution; their
composition precisely corresponded to the target com-
pound.
For Cs[H IO · H IO · 0.5H O] anal. calcd., wt %: product displayed bands associated with the nitrate-
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6
2
–
1
I, 42.6; Cs, 22.3.
ion vibrations (cm ): 1045 (ν ), 1462 (ν ), 718 (ν ).
1 2 3
–
1
Found, wt %: I, 42.4; Cs, 22.4.
The crystals were stable in air. Heating them in a
In addition, there were a very strong band at 659 cm
and a broad band with three maxima at 401, 380, and
sealed glass capillary, we observed rounded edges with 372 cm ; these bands closely correlate with the bands
a microscope at 50–52°ë; the crystals looked wet, but associated with the ν
–
1
and ν vibrations of the IO
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1
+
full melting did not occur.
octahedron in the (H IO ) cation in hexahydroxoi-
6
6
odonium sulfate, hydrosulfate, and hydroselenate [9,
1
0]. From this, we can infer that we obtained a mixed
Cs[H IO · H IO ] Synthesis
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salt, namely cesium hexahydroxoiodonium nitrate
At room temperature, in 30% nitric acid (3.9 g) dis-
Cs (H IO )(NO ) .
2
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6
3 3
solved were CsNO (1.5 g, 7.7 mmol) and H IO
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6
(
3.5 g, 15.36 mmol). The molar ratio of the components
Rb[H IO · H IO ] Synthesis
was CsNO : HNO : H IO = 1 : 2.0 : 2.6. The solution
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3
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6
was allowed to stand for several days in a desiccator
with calcium chloride as a drier and ascarite as an agent
This was the only rubidium analogue of the above-
described cesium salts that we managed to prepare.
This salt crystallized under the conditions similar to the
to bind HNO vapor. Large (up to 10 mm) clear crystals
3
of the anhydrous complex Cs[H IO · H IO ] were crystallization conditions for 2CsNO · HNO · H IO ,
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5
6
3
3
5
6
slowly formed in the solution.
For Cs[H IO · H IO ] anal. calcd., wt %: I, 43.2; acid (12.2 g), dissolved were RbNO
but the component ratio was different. In 56% nitric
(1.6 g, 10.9 mmol)
(5.7 g, 25.0 mmol). The molar ratio in the
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5
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3
Cs, 22.6.
and H IO
5 6
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 52 No. 11 2007