Gadolinium(III) chloride

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Gadolinium(III) chloride
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Gadolinium(III) chloride.jpg
Names
IUPAC name
Gadolinium(III) chloride
Other names
Gadolinium trichloride
Gadolinium chloride
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.030.338 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • InChI=1S/3ClH.Gd/h3*1H;/q;;;+3/p-3 Yes check.svgY
    Key: MEANOSLIBWSCIT-UHFFFAOYSA-K Yes check.svgY
  • InChI=1/3ClH.Gd/h3*1H;/q;;;+3/p-3
    Key: MEANOSLIBWSCIT-DFZHHIFOAP
  • Cl[Gd](Cl)Cl
Properties
GdCl3
Molar mass 263.61 g/mol
Appearancewhite crystals
hygroscopic
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)
94.65 g/100mL, 25°C [1]
+27,930·10−6 cm3/mol
Structure
hexagonal, hP8
P63/m, No. 176
Related compounds
Other anions
Gadolinium(III) fluoride
Gadolinium(III) bromide
Gadolinium(III) oxide
Other cations
Europium(III) chloride
Terbium(III) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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.

Contents

Preparation

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: [2]

10 NH4Cl + Gd2O3 → 2 (NH4)2[GdCl5] + 6 NH3 + 3 H2O

from hydrated gadolinium chloride:

4 NH4Cl + 2 GdCl3∙6H2O → 2 (NH4)2[GdCl5] + 12 H2O

from gadolinium metal:

10 NH4Cl + 2 Gd → 2 (NH4)2[GdCl5] + 6 NH3 + 3 H2

In the second step the pentachloride is decomposed at 300 °C:

(NH4)2[GdCl5] → GdCl3 + 2 NH4Cl

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. [3]

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. [4]

Structure

GdCl3 crystallizes with a hexagonal UCl3 structure, as seen for other 4f trichlorides including those of La, Ce, Pr, Nd, Pm, Sm, Eu. [5] 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.

Properties, with applications to MRI

Gadolinium salts are of primary interest for relaxation agents in magnetic resonance imaging (MRI). This technique exploits the fact that Gd3+ has an electronic configuration of f7. Seven is the largest number of unpaired electron spins possible for an atom, so Gd3+ is a key component in the design of highly paramagnetic complexes. [6] To generate the relaxation agents, Gd3+ sources such as GdCl3∙6H2O are converted to coordination complexes. GdCl3∙6H2O can not be used as an MRI contrasting agent due to its low solubility in water at the body's near neutral pH. [7] "Free" gadolinium(III), e.g. [GdCl2(H2O)6]+, is toxic, so chelating agents are essential for biomedical applications. Simple monodentate or even bidentate ligands will not suffice because they do not remain bound to Gd3+ in solution. Ligands with higher coordination numbers therefore are required. The obvious candidate is EDTA 4−, ethylenediaminetetraacetate, which is a commonly employed hexadentate ligand used to complex to transition metals. In lanthanides, however, exhibit coordination numbers greater than six, so still larger aminocarboxylates are employed.

One representative chelating agent is H5DTPA, diethylenetriaminepentaacetic acid. [8] Chelation to the conjugate base of this ligand increases the solubility of the Gd3+ at the body's neutral pH and still allows for the paramagnetic effect required for an MRI contrast agent. The DTPA5− ligand binds to Gd through five oxygen atoms of the carboxylates and three nitrogen atoms of the amines. A 9th binding site remains, which is occupied by a water molecule. The rapid exchange of this water ligand with bulk water is a major reason for the signal enhancing properties of the chelate. The structure of [Gd(DTPA)(H2O)]2− is a distorted tricapped trigonal prism.

The following is the reaction for the formation of Gd-DTPA:

Gd DTPA rxn (2).PNG

Related Research Articles

Neodymium(III) chloride or neodymium trichloride is a chemical compound of neodymium and chlorine with the formula NdCl3. This anhydrous compound is a mauve-colored solid that rapidly absorbs water on exposure to air to form a purple-colored hexahydrate, NdCl3·6H2O. Neodymium(III) chloride is produced from minerals monazite and bastnäsite using a complex multistage extraction process. The chloride has several important applications as an intermediate chemical for production of neodymium metal and neodymium-based lasers and optical fibers. Other applications include a catalyst in organic synthesis and in decomposition of waste water contamination, corrosion protection of aluminium and its alloys, and fluorescent labeling of organic molecules (DNA).

<span class="mw-page-title-main">Samarium(III) chloride</span> Chemical compound

Samarium(III) chloride, also known as samarium trichloride, is an inorganic compound of samarium and chloride. It is a pale yellow salt that rapidly absorbs water to form a hexahydrate, SmCl3.6H2O. The compound has few practical applications but is used in laboratories for research on new compounds of samarium.

<span class="mw-page-title-main">Europium(III) chloride</span> Chemical compound

Europium(III) chloride is an inorganic compound with the formula EuCl3. The anhydrous compound is a yellow solid. Being hygroscopic it rapidly absorbs water to form a white crystalline hexahydrate, EuCl3·6H2O, which is colourless. The compound is used in research.

<span class="mw-page-title-main">Aluminium chloride</span> Chemical compound

Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula AlCl3. It forms hexahydrate with the formula [Al(H2O)6]Cl3, containing six water molecules of hydration. Both are colourless crystals, but samples are often contaminated with iron(III) chloride, giving a yellow color.

<span class="mw-page-title-main">Dysprosium(III) chloride</span> Chemical compound

Dysprosium(III) chloride (DyCl3), also known as dysprosium trichloride, is a compound of dysprosium and chlorine. It is a white to yellow solid which rapidly absorbs water on exposure to moist air to form a hexahydrate, DyCl3·6H2O. Simple rapid heating of the hydrate causes partial hydrolysis to an oxychloride, DyOCl.

<span class="mw-page-title-main">Chromium(III) chloride</span> Chemical compound

Chromium(III) chloride (also called chromic chloride) describes any of several chemical compounds with the formula CrCl3 · xH2O, where x can be 0, 5, and 6. The anhydrous compound with the formula CrCl3 is a violet solid. The most common form of the trichloride is the dark green hexahydrate, CrCl3 · 6 H2O. Chromium chlorides find use as catalysts and as precursors to dyes for wool.

<span class="mw-page-title-main">Nickel(II) chloride</span> Chemical compound

Nickel(II) chloride (or just nickel chloride) is the chemical compound NiCl2. The anhydrous salt is yellow, but the more familiar hydrate NiCl2·6H2O is green. Nickel(II) chloride, in various forms, is the most important source of nickel for chemical synthesis. The nickel chlorides are deliquescent, absorbing moisture from the air to form a solution. Nickel salts have been shown to be carcinogenic to the lungs and nasal passages in cases of long-term inhalation exposure.

<span class="mw-page-title-main">Phosphorus trichloride</span> Chemical compound

Phosphorus trichloride is an inorganic compound with the chemical formula PCl3. A colorless liquid when pure, it is an important industrial chemical, being used for the manufacture of phosphites and other organophosphorus compounds. It is toxic and reacts readily with water to release hydrogen chloride.

<span class="mw-page-title-main">Terbium(III,IV) oxide</span> Chemical compound

Terbium(III,IV) oxide, occasionally called tetraterbium heptaoxide, has the formula Tb4O7, though some texts refer to it as TbO1.75. There is some debate as to whether it is a discrete compound, or simply one phase in an interstitial oxide system. Tb4O7 is one of the main commercial terbium compounds, and the only such product containing at least some Tb(IV) (terbium in the +4 oxidation state), along with the more stable Tb(III). It is produced by heating the metal oxalate, and it is used in the preparation of other terbium compounds. Terbium forms three other major oxides: Tb2O3, TbO2, and Tb6O11.

<span class="mw-page-title-main">Erbium(III) chloride</span> Chemical compound

Erbium(III) chloride is a violet solid with the formula ErCl3. It is used in the preparation of erbium metal.

<span class="mw-page-title-main">Gadopentetic acid</span> Complex of gadolinium by DTPA

Gadopentetic acid, sold under the brand name Magnevist, is a gadolinium-based MRI contrast agent.

<span class="mw-page-title-main">Vanadium(III) chloride</span> Chemical compound

Vanadium trichloride is the inorganic compound with the formula VCl3. This purple salt is a common precursor to other vanadium(III) complexes.

<span class="mw-page-title-main">Pentetic acid</span> DTPA: aminopolycarboxylic acid

Pentetic acid or diethylenetriaminepentaacetic acid (DTPA) is an aminopolycarboxylic acid consisting of a diethylenetriamine backbone with five carboxymethyl groups. The molecule can be viewed as an expanded version of EDTA and is used similarly. It is a white solid with limited solubility in water.

<span class="mw-page-title-main">Yttrium(III) chloride</span> Chemical compound

Yttrium(III) chloride is an inorganic compound of yttrium and chloride. It exists in two forms, the hydrate (YCl3(H2O)6) and an anhydrous form (YCl3). Both are colourless solids that are highly soluble in water and deliquescent.

<span class="mw-page-title-main">Ytterbium(III) chloride</span> Chemical compound

Ytterbium(III) chloride (YbCl3) is an inorganic chemical compound. It reacts with NiCl2 to form a very effective catalyst for the reductive dehalogenation of aryl halides. It is poisonous if injected, and mildly toxic by ingestion. It is an experimental teratogen, known to irritate the skin and eyes. When heated to decomposition it emits toxic fumes of Cl−.

Lanthanum chloride is the inorganic compound with the formula LaCl3. It is a common salt of lanthanum which is mainly used in research. It is a white solid that is highly soluble in water and alcohols.

<span class="mw-page-title-main">Triphenylarsine</span> Chemical compound

Triphenylarsine is the chemical compound with the formula As(C6H5)3. This organoarsenic compound, often abbreviated AsPh3, is a colorless crystalline solid that is used as a ligand and a reagent in coordination chemistry and organic synthesis. The molecule is pyramidal with As-C distances of 1.942–1.956 Å and C-As-C angles of 99.6–100.5°.

Gadolinium(III) fluoride is an inorganic compound with a chemical formula GdF3.

Lanthanide trichlorides are a family of inorganic compound with the formula LnCl3, where Ln stands for a lanthanide metal. The trichlorides are standard reagents in applied and academic chemistry of the lanthanides. They exist as anhydrous solids and as hydrates.

<span class="mw-page-title-main">Berkelium(III) chloride</span> Chemical compound

Berkelium(III) chloride also known as berkelium trichloride, is a chemical compound with the formula BkCl3. It is a water-soluble green solid with a melting point of 603 °C. This compound forms the hexahydrate, BkCl3·6H2O.

References

  1. ↑ Saeger, Victor William; Spedding, F. H. (November 1960). Some physical properties of rare-earth chlorides in aqueous solution. Ames Laboratory Technical Reports 46. p. 38. Retrieved 19 October 2020.
  2. ↑ Meyer, G. (1989). The Ammonium Chloride Route to Anhydrous Rare Earth Chlorides-The Example of YCl3. Inorganic Syntheses. Vol. 25. pp. 146–150. doi:10.1002/9780470132562.ch35. ISBN   978-0-470-13256-2.
  3. ↑ Corbett, John D. (1983). "Trichlorides of the Rare Earth Elements, Yttrium, and Scandium". Inorganic Syntheses. Inorganic Syntheses. Vol. 22. pp. 39–42. doi:10.1002/9780470132531.ch8. ISBN   978-0-470-13253-1.
  4. ↑ Quill, L. L.; Clink, George L. (1967). "Preparation of Lanthanide Chloride Methanolates Using 2,2-Dimethoxypropane". Inorganic Chemistry. 6 (7): 1433–1435. doi:10.1021/ic50053a032.
  5. ↑ Wells, A.F. (1984). Structural Inorganic Chemistry. Oxford: Clarendon Press.
  6. ↑ Raduchel, B.; Weinmann, H.; Muhler, A. (1996). "Gadolinium Chelates: Chemistry, Safety, & Behavior". Encyclopedia of Nuclear Magnetic Resonance. 4: 2166–2172.
  7. ↑ Spencer, A. J.; Wilson, S. A.; Batchelor, J.; Reid, A.; Pees, J.; Harpur, E. (1997). "Gadolinium Chloride Toxicity in the Rat". Toxicologic Pathology. 25 (3): 245–255. doi:10.1177/019262339702500301. ISSN   0192-6233. PMID   9210255. S2CID   19838648.
  8. ↑ Aime, S.; Botta, Mauro; Dastru, Walter; Fasano, Mauro; Panero, Maurizio; Arnelli, Aldo (1993). "Synthesis and Characterization of a Novel DPTA-like Gadolinium(III) Complex: A Potential Reagent for the Determination of Glycated Proteins by Water Proton NMR Relaxation Measurements". Inorganic Chemistry. 32 (10): 2068–2071. doi:10.1021/ic00062a031.
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