Gallium (III) chloride

Crystal structure
__ Ga 3+      __ Cl -
Crystal system	monoclinic
Space group	C 2 / m (No. 12)
Lattice parameters	a = 11.948  Å , b = 6.855 Å, c = 7.050 Å, β = 125.69 °
General
Surname	Gallium (III) chloride
other names	Gallium trichloride
Ratio formula	GaCl 3
Brief description	white solid
External identifiers / databases
CAS number 13450-90-3 EC number 236-610-0 ECHA InfoCard 100.033.268 PubChem 26010 Wikidata Q31153
properties
Molar mass	176.08 g mol −1
Physical state	firmly
density	2.47 g cm −3
Melting point	77.9 ° C
boiling point	201.3 ° C
solubility	reacts violently with water, soluble in dry toluene, benzene and diethyl ether
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 314 P: 280-305 + 351 + 338-310
Thermodynamic properties
ΔH f 0	−525 kJ mol −1
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Gallium (III) chloride is a chemical compound of gallium and is one of the chlorides . The Lewis acid exists as a dimer and is used in organic reactions .

Extraction and presentation

Gallium (III) chloride can be derived directly from the elements gallium and chlorine :

${\displaystyle {\ce {2Ga + 3Cl2 -> 2GaCl3}}}$

by converting elemental gallium in the HCl stream:

${\displaystyle {\ce {2 Ga + 6 HCl -> 2 GaCl3 + 3 H2}}}$

or by the action of thionyl chloride on gallium (III) oxide at about 200 ° C:

${\displaystyle {\ce {Ga2O3 + 3 SOCl2 -> 2 GaCl3 + 3 SO2}}}$

properties

Like other halides of the third main group, gallium (III) chloride forms dimers of the form Ga ₂ Cl ₆ with four terminal and two capped chlorine atoms. In the solid state, these are analogous to the aluminum (III) bromide structure in the form of edge-sharing tetrahedra ( monoclinic crystal structure, space group C 2 / m (space group no.12 ) , a = 11.948 Å , b = 6.855 Å, c = 7.050 Å , β = 125.69 °). This is in contrast to the structure of aluminum (III) chloride , which forms a layer structure .

Gallium (III) chloride is very hygroscopic and reacts strongly with water. Evaporation of an aqueous solution gives off hydrogen chloride . Like other halides of aluminum , gallium, and indium , gallium (III) chloride is a strong Lewis acid. With the appropriate Lewis bases such as halide ions, ethers , amines or phosphines , it forms stable Lewis acid-base adducts. In comparison with aluminum (III) chloride, gallium (III) chloride reacts better with soft Lewis bases (such as phosphines), while hard Lewis bases react better with aluminum (III) chloride.

In a vacuum it can be sublimated below its melting point and thus purified.

use

In contrast to many other gallium compounds, gallium (III) chloride is used in technology; it serves as a Lewis acid in Friedel-Crafts reactions .

In the GALLEX experiment to detect neutrinos , a solution of 100 tons of gallium (III) chloride in hydrochloric acid was used.

Gallium-68 chloride can be used for skeletal scintigraphy using positron emission tomography . Because of the high positron range of the Ga-68, the spatial resolution that can be achieved with F-18 (as sodium fluoride ) is not achieved, but the Gallium-68 generator does not require a cyclotron .

Individual evidence

1. ↑ ^{a b c} data sheet Gallium (III) chloride from Sigma-Aldrich , accessed on April 2, 2011 ( PDF ).
2. ↑ ^{a b c d} data sheet gallium (III) chloride from AlfaAesar, accessed on May 13, 2009 ( PDF )(JavaScript required) .
3. ↑ Cheng-Tzu Yang, Michael H. Huang: Formation of Arrays of Gallium Nitride Nanorods within Mesoporous Silica SBA-15 . In: Journal of Physical Chemistry B . tape 109 , no. 38 , 2005, p. 17842-17847 , doi : 10.1021 / jp052228k .
4. ^ OT Beachley, Melvyn Rowen. Churchill, John C. Pazik, Joseph W. Ziller: Synthesis and characterization of mesitylgallium chloride compounds including the crystal and molecular structure of dichloromesitylgallium (III), an inorganic polymer . In: Organometallics . tape 6 , no. 10 , 1987, pp. 2088-2093 , doi : 10.1021 / om00153a010 .
5. ^ AF Holleman , N. Wiberg : Inorganische Chemie . 103rd edition. Volume 1: Basics and main group elements. Walter de Gruyter, Berlin / Boston 2016, ISBN 978-3-11-049585-0 , p. 1393 (reading sample: Part A - Basics of the chemistry of hydrogen. Google book search ).
6. ^ ^{A b c} A. F. Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , pp. 1190-1192.
7. ↑ ^{a b c} W. C. Johnson and Caleb A. Haskew: Gallium trichloride . In: Harold Simmons Booth (Ed.): Inorganic Syntheses . tape 1 . McGraw-Hill, Inc., 1939, p. 26-27 (English).
8. ^ Georg Brauer: Gallium (III) chloride . In: Handbook of Preparative Inorganic Chemistry . Ferdinand Enke Verlag, Stuttgart 1954, p. 635 f .
9. ↑ SI Troyanov, T. Krahl, E. Kemnitz: Crystal structures of GaX ₃ (X = Cl, Br, I) and AlI ₃ . In: Journal of Crystallography . tape 219 , no. 2 , 2004, p. 88-92 , doi : 10.1524 / zkri.219.2.88.26320 .
10. ↑ ^{a b} Entry on gallium compounds. In: Römpp Online . Georg Thieme Verlag, accessed on June 13, 2014.