Lanthanide trichloride: Difference between revisions
→Uses: general statements |
Holmium |
||
| Line 31: | Line 31: | ||
| DyCl<sub>3</sub> || white || YCl<sub>3</sub>-type || - |
| DyCl<sub>3</sub> || white || YCl<sub>3</sub>-type || - |
||
|- |
|- |
||
| HoCl<sub>3</sub> || yellow || - || - |
| HoCl<sub>3</sub> || yellow || YCl<sub>3</sub>-type || - |
||
|- |
|- |
||
| ErCl<sub>3</sub> || violet || - || - |
| ErCl<sub>3</sub> || violet || - || - |
||
Revision as of 16:25, 15 January 2022
Lanthanide trichlorides are a family of inorganic compound with the formula LnCl3. They are widely used reagents. They exist as anhydrous solids and as hydrates. The anhydrous solids have melting points range from ca. 582 (Tb) - 925 °C (Lu).
| MCl3 | color | structure type | comment |
|---|---|---|---|
| ScCl3 | colorless | - | not classified as a lanthanide usually |
| YCl3 | colorless | YCl3-type | not classified as a lanthanide usually |
| LaCl3 | colorless | UCl3-type | - |
| CeCl3 | colorless | UCl3-type | - |
| PrCl3 | green | UCl3-type | - |
| NdCl3 | piink | UCl3-type | - |
| PmCl3 | green | UCl3-type | radioactive |
| SmCl3 | yellow | UCl3-type | - |
| EuCl3 | yellow | UCl3-type | - |
| GdCl3 | colorless | UCl3-type | - |
| TbCl3 | white | PuBr3-type | - |
| DyCl3 | white | YCl3-type | - |
| HoCl3 | yellow | YCl3-type | - |
| ErCl3 | violet | - | - |
| TmCl3 | yellow | - | - |
| YbCl3 | colorless | - | - |
| LuCl3 | colorless | YCl3-type | - |
Preparation
Ammonium chloride route
The ammonium chloride route refers to a set of procedures used to produce anhydrous lanthanide chlorides. The method has the advantages of being general for the 14 lanthanides and it produces air-stable intermediates that resist hydrolysis. The use of ammonium chloride as a reagent is convenient because the salt is anhydrous, even when handled in air. Ammonium chloride is also attractive because it thermally decomposes to volatile products at temperatures compatible with the stability of the trichloride targets.[2][3][4]
Step 1: preparation of ammonium lanthanide chlorides
The reaction of an intimate mixture of lanthanide oxides with ammonium chloride produces anhydrous ammonium salts of the penta- and hexachlorides. Typical reaction conditions are hours at 230-250 °C.[3] Some lanthanides (as well as scandium and yttrium form pentachlorides:
- M2O3 + 10 NH4Cl → 2 (NH4)2MCl5 + 3 H2O + 6 NH3
(M = Dy, Ho, Er, Tm, Lu, Yb, Y, Sc)
- Tb4O7 + 22 NH4Cl → 4 (NH4)2TbCl5 + 7 H2O + 14 NH3
Other lanthanides for hexachlorides:
- M2O3 + 12 NH4Cl → 2 (NH4)3MCl6 + 3 H2O + 6 NH3
(M = La, Ce, Nd, Pm, Sm, Eu, Gd)
- Pr6O11 + 40 NH4Cl → 6 (NH4)3PrCl6 + 11 H2O + 22 NH3
These reactions can also start with the metals, e.g.:[3]
- Y + 5 NH4Cl → (NH4)2YCl5 + 1.5 H2 + 3 NH3
Step 2: thermolysis of ammonium lanthanide chlorides
The ammonium lanthanum chlorides are converted to the trichlorides by heating in a vacuum. Typical reaction temperatures are 350–400 °C:[3]
- (NH4)2MCl5 → MCl3 + 2 HCl + 2 NH3
- (NH4)3MCl6 → MCl3 + 3 HCl + 3 NH3
Uses
Lanthanide trichloriides are precursors to the metals. They are also useful precursors to organometallic derivatives.
References
- ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
- ^ Brauer, G., ed. (1963). Handbook of Preparative Inorganic Chemistry (2nd ed.). New York: Academic Press.
- ^ a b c d 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.
- ^ Edelmann, F. T.; Poremba, P. (1997). Herrmann, W. A. (ed.). Synthetic Methods of Organometallic and Inorganic Chemistry. Vol. VI. Stuttgart: Georg Thieme Verlag. ISBN 978-3-13-103021-4.