ISSN 0036-0236, Russian Journal of Inorganic Chemistry, 2008, Vol. 53, No. 6, p. 849. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © S.I. Bakum, S.F. Kuznetsova, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 6, p. 919.
SYNTHESIS AND PROPERTIES
OF INORGANIC COMPOUNDS
On the Preparation of Calcium Gallohydride
S. I. Bakum and S. F. Kuznetsova
Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia
Received April 3, 2007
Abstract—The reaction of CsGaH4 or RbGaH4 with ë‡I2 in THF produced calcium gallohydride CaHGaH4 ·
THF (I). DTA showed that compound I decomposes with an endotherm in the range 116–130°ë. CaHGaH4 ·
THF is well soluble in diglyme. In the IR spectrum of compound I, there is a strong band at 1780 cm–1, which
is intrinsic to the Ga–H stretching vibrations.
DOI: 10.1134/S0036023608060041
The literature offers no data on the preparation of in THF compared to the solubilities of RbGaH4 and
alkali metal gallohydrides. Here, we attempted to pre-
pare calcium gallohydride. The reagents used were
ë‡I2 and cesium or rubidium gallohydride synthesized
as in [1]. Anhydrous calcium iodide (~99%) was pre-
pared by an original procedure, which involved the fol-
lowing operations:
(i) a mixture of ë‡I2 with excess ë‡ç2 was obtained
as a result of slow addition of an I2 solution in diethyl
ether to a suspension of finely divided calcium hydride
in diethyl ether; complete decoloration of diethyl ether
indicated the end of the reaction;
RbI. The product compound was isolated as a white
powder by distillation of the solvent.
In the product, chemical analysis found, wt %: Ga,
37.20; Ca, 21.32; C, 25.90. The atomic ratio Ga : Ca in
the compound was 1 : 1, as determined by mass spec-
trometry. Based on this, the compound was formulated
as CaHGaH4 · THF. For this formula, anal. calcd., wt %:
Ga, 37.29; Ca, 21.44; C, 25.70.
DTA showed that compound I intensely decom-
posed in an inert atmosphere with an endotherm in the
range 116–130°ë with the evolution of ~60% of the
hydride hydrogen. Calcium hydride and metallic gal-
lium are the most likely thermolysis products. The IR
spectrum of compound I contains a strong absorption
band at 1780 cm–1, which is characteristic of the Ga–H
stretching vibrations. The compound is well soluble in
diglyme, as all known gallohydrides, and rapidly
hydrolyzes in air.
(ii) ë‡I2 was extracted by acetonitrile from the
resulting mixture;
(iii) pure anhydrous ë‡I2 was isolated from an ace-
tonitrile solution as a white powder by concentrating
the solution at 60°ë.
Calcium and gallium were determined by complex-
ometric titration [2]; iodine was determined by the Vol-
gard technique.
The reaction between ë‡I2 and CsGaH4 (RbGaH4)
was carried out in THF at room temperature with vig-
orous stirring. Complete ë‡I2 conversion was achieved
in 6–8 h with an eightfold excess of gallohydride. The
use of cesium gallohydride was preferable because of
the lower (virtually null) solubilities of CsGaH4 and CsI
REFERENCES
1. S. I. Bakum and S. F. Ereshko, Izv. Akad. Nauk SSSR,
Ser. Khim. 2183 (1981).
2. G. Schwarzenbach and H. Flaschka, Die complexnome-
trische Titration (Ferdinand Enke, Stuttgart, 1976;
Khimiya, Moscow, 1970).
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