Gadolinium(III) chloride
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| Names | |||
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| Other names
Gadolinium trichloride
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| Identifiers | |||
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3D model (JSmol)
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| ChEBI | |||
| ChemSpider | |||
| ECHA InfoCard | 100.030.338 | ||
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PubChem CID
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| Properties | |||
| GdCl3 | |||
| Molar mass | 263.61 g/mol | ||
| Appearance | white crystals hygroscopic |
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| Density | 4.52 g/cm3 | ||
| Melting point | 609 °C (1,128 °F; 882 K) | ||
| Boiling point | 1,580 °C (2,880 °F; 1,850 K) | ||
| soluble | |||
| +27,930·10−6 cm3/mol | |||
| Structure | |||
| hexagonal, hP8 | |||
| P63/m, No. 176 | |||
| Related compounds | |||
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Other anions
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Gadolinium(III) oxide | ||
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Other cations
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Europium(III) chloride, Terbium(III) chloride | ||
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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| Infobox references | |||
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Gadolinium(III) chloride, also known as gadolinium trichloride, is GdCl3. It is a colorless, hygroscopic, water-soluble solid. The hexahydrate GdCl3∙6H2O is commonly encountered and is sometimes also called gadolinium trichloride. Gd3+ species are of special interest because the ion has the maximum number of unpaired spins possible, at least for known elements. With seven valence electrons and seven available f-orbitals, all seven electrons are unpaired and symmetrically arranged around the metal. The high magnetism and high symmetry combine to make Gd3+ a useful component in NMR spectroscopy and MRI.
GdCl3 is usually prepared by the "ammonium chloride" route, which involves the initial synthesis of (NH4)2[GdCl5]. This material can be prepared from the common starting materials at reaction temperatures of 230 °C from gadolinium oxide:
from hydrated gadolinium chloride:
from gadolinium metal:
In the second step the pentachloride is decomposed at 300 °C:
This pyrolysis reaction proceeds via the intermediacy of NH4[Gd2Cl7].
The ammonium chloride route is more popular and less expensive than other methods. GdCl3 can, however, also be synthesized by the reaction of solid Gd at 600 °C in a flowing stream of HCl.
Gadolinium(III) chloride also forms a hexahydrate, GdCl3∙6H2O. The hexahydrate is prepared by gadolinium(III) oxide (or chloride) in concentrated HCl followed by evaporation.
GdCl3 crystallizes with a hexagonal UCl3 structure, as seen for other 4f trichlorides including those of La, Ce, Pr, Nd, Pm, Sm, Eu. The following crystallize in theYCl3 motif: DyCl3, HoCl3, ErCl3, TmCl3, YdCl3, LuCl3, YCl3). The UCl3 motif features 9-coordinate metal with a tricapped trigonal prismatic coordination sphere. In the hexahydrate of gadolinium(III) chloride and other smaller 4f trichlorides and tribromides, six H2O molecules and 2 Cl−ions coordinate to the cations resulting in a coordination group of 8.
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