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|Section2= |Section3= |Section7= |Section8= }} 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. ==Preparation== GdCl3 is usually prepared by the "ammonium chloride" route, which involves the initial synthesis of (NH4)2(). This material can be prepared from the common starting materials at reaction temperatures of 230 °C from gadolinium oxide:〔 〕 ::10 NH4Cl + Gd2O3 → 2 (NH4)2() + 6 NH3 + 3 H2O from hydrated gadolinium chloride: ::4 NH4Cl + 2 GdCl3∙6H2O → 2 (NH4)2() + 12 H2O from gadolinium metal: ::10 NH4Cl + 2 Gd → 2 (NH4)2() + 6 NH3 + 3 H2 In the second step the pentachloride is decomposed at 300 °C: :: (NH4)2() → GdCl3 + 2 NH4Cl This pyrolysis reaction proceeds via the intermediacy of NH4(). 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. ::Gd + 3 HCl → GdCl3 + 3/2 H2 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Gadolinium(III) chloride」の詳細全文を読む スポンサード リンク
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