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Neodymium compounds are compounds formed by the lanthanide metal neodymium (Nd). In these compounds, neodymium generally exhibits the +3 oxidation state, such as NdCl₃, Nd₂(SO₄)₃ and Nd(CH₃COO)₃. Compounds with neodymium in the +2 oxidation state are also known, such as NdCl₂ and NdI₂. Some neodymium compounds have colors that vary based upon the type of lighting.^[1]

Neodymium compounds in fluorescent tube light—from left to right, the sulfate, nitrate, and chloride
Neodymium compounds in compact fluorescent lamp light
Neodymium compounds in normal daylight

Halides

NdCl₃ under sunlight (top) and fluorescent light (bottom)

Neodymium can form four trihalides of the form NdX₃. It reacts vigorously with all the stable halogens:^[2]

2Nd (s) + 3F₂ (g) → 2NdF₃ (s) [a violet substance]

2Nd (s) + 3Cl₂ (g) → 2NdCl₃ (s) [a mauve substance]

2Nd (s) + 3Br₂ (g) → 2NdBr₃ (s) [a violet substance]

2Nd (s) + 3I₂ (g) → 2NdI₃ (s) [a green substance]

The dihalides NdCl₂ and NdBr₂ are dark green solids,^[3] with the same crystal structure as PbCl₂^[3] and NdI₂ is a dark purple solid. They can be obtained in the Nd-NdX₃ eutectic system.^[4]

NdF₄ is known only under matrix isolation conditions.^[5] The related M₃[NdF₇] (M = K, Rb, Cs) are very unstable towards moisture or heat.^[6] They can be prepared by high-pressure fluorination or from noble gas fluorides.^[7]

Oxygenated salts

Neodymium(III) sulfate can be directly obtained by dissolving neodymium(III) oxide in sulfuric acid.^[8] It is soluble in water, and its anhydrous form has a solubility of 8 g at 20˚C. Neodymium(III) nitrate can be obtained by dissolving neodymium(III) oxide in nitric acid.^[9] Evaporating the resulting solution yields hydrated neodymium(III) nitrate, where the hexahydrate form is the most common. Heating the hexahydrate further will obtain the anhydrous form. Reacting neodymium(III) chloride with sodium arsenate in solution would obtain neodymium(III) arsenate,^[10] which is a faint pink powder that is insoluble in water. It has good thermal stability, and its solubility product pK_sp,c is 21.86±0.11.^[11] Neodymium(III) oxalate is a rose-coloured crystal which decomposes from its decahydrate to its anhydrous form when heated, and when heated further, decomposes to Nd₂O₂C₂O₄,^[12] and then finally obtaining neodymium(III) oxide.^[13] Neodymium(III) carbonate is the carbonate of neodymium where neodymium exhibits the +3 oxidation state. It can be obtained by reacting neodymium(III) chloride with ammonium bicarbonate in water or from the hydrolysis of neodymium(III) chloroacetate:^[14]

2Nd(C₂Cl₃O₂)₃ + 3H₂O → Nd₂(CO₃)₃ + 6CHCl₃ + 3CO₂

Neodymium(III) acetate is a purple solid^[15] that is soluble in water.^[16]^[17] The solubility of the compound increases when sodium acetate is added, forming a blue complex.^[18] It can be obtained by the reaction of neodymium(III) chloride and sodium acetate:^[19]

NdCl₃ + 3Na(CH₃COO) → Nd(CH₃COO)₃ + 3NaCl

Organoneodymium compounds

Organoneodymium compounds are compounds that have a neodymium–carbon bond. These compounds are similar to those of the other lanthanides, characterized by an inability to undergo π backbonding. They are thus mostly restricted to the mostly ionic cyclopentadienides (isostructural with those of lanthanum) and the σ-bonded simple alkyls and aryls, some of which may be polymeric.^[20]

Applications

Neodymium(III) chloride does not have strong luminescence,^[21] though it serves as a source of Nd³⁺ ions for various light emitting materials. The latter include Nd-YAG lasers and Nd-doped optical fiber amplifiers, which amplify light emitted by other lasers. The Nd-YAG laser emits infrared light at 1.064 micrometres and is the most popular solid-state laser (i.e. laser based on a solid medium).

Neodymium glass (Nd:glass) is produced by the inclusion of neodymium(III) oxide (Nd₂O₃) in the glass melt. Usually in daylight or incandescent light neodymium glass appears lavender, but it appears pale blue under fluorescent lighting. Neodymium may be used to color glass in delicate shades ranging from pure violet through wine-red and warm gray.^[22]

Neodymium(III) acetate can be used as a substitute for uranyl acetate,^[23] which is used in electron microscopy.^[24]

References

^ Burke M.W. (1996) Lighting II: Sources. In: Image Acquisition. Springer, Dordrecht. doi:10.1007/978-94-009-0069-1_2
^ Neodymium: reactions of elements Archived 2022-11-12 at the Wayback Machine. WebElements. [2017-4-10]
^ ^a ^b Georg Brauer (Hrsg.), unter Mitarbeit von Marianne Baudler u. a.: Handbuch der Präparativen Anorganischen Chemie. 3., umgearbeitete Auflage. Band I, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6, S. 1081.
^ Leonard F. Druding, John D. Corbett (October 1959). "Rare Earth Metal-Metal Halide Systems. The Preparation of Neodymium(Ii) Halides". Journal of the American Chemical Society. 81 (20): 5512. doi:10.1021/ja01529a067. ISSN 0002-7863. Retrieved 2022-07-19.
^ Vent-Schmidt, Thomas; Fang, Zongtang; Lee, Zachary; Dixon, David; Riedel, Sebastian (2016-01-20). "Extending the Row of Lanthanide Tetrafluorides: A Combined Matrix-Isolation and Quantum-Chemical Study". Chemistry - A European Journal. 22 (7). Wiley: 2406–2416. doi:10.1002/chem.201504182. hdl:2027.42/137267. ISSN 0947-6539. PMID 26786900.
^ Meyer, G.; Morss, L.R. (2012-12-06). Synthesis of Lanthanide and Actinide Compounds. Springer Science & Business Media. p. 63. ISBN 978-94-011-3758-4.
^ Riedel, S. (2013). "High-Valent Fluorides and Fluoro-Oxidizers". Comprehensive Inorganic Chemistry II. Elsevier. pp. 187–221. doi:10.1016/b978-0-08-097774-4.00208-4. ISBN 9780080965291.
^ 《无机化合物制备手册》.朱文祥主编. 化学工业出版社. P₇₀₁. 【XVI-97】八水硫酸钕（neodymium sulfate octahydrate）
^ 《无机化学丛书》.第七卷钪稀土元素. P₂₃₃. 11.硝酸盐及其复盐
^ Gabisoniya, Ts. D.; Nanobashvili, E. M.. Synthesis of rare earth metal arsenates. Soobshcheniya Akademii Nauk Gruzinskoi SSR (1980), 97(2), 345-8. ISSN 0002-3167
^ Firsching, F. Henry. Solubility products of the trivalent rare-earth arsenates. Journal of Chemical and Engineering Data, 1992. 37 (4): 497-499. DOI:10.1021/je00008a028
^ Gunther, Paul L.; Rehaag, Hildegard. The thermal decomposition of oxalates. I. The formation of peroxides by the thermal decomposition of oxalates in a vacuum. Berichte der Deutschen Chemischen Gesellschaft [Abteilung] B: Abhandlungen. 1938. 71B: 1771-1777. ISSN: 0365-9488.
^ Wendlandt, W. W. (1959). "Thermal Decomposition of Rare Earth Metal Oxalates". Analytical Chemistry. 31 (3): 408–410. doi:10.1021/ac60147a024. ISSN 0003-2700.
^ 《无机化学丛书》. 第七卷钪稀土元素. 易宪武黄春晖等编.科学出版社. tr. 174, 碳酸盐. ISBN 978-7-03-030574-9
^ Sonia Gomez Torres, Gerd Meyer (2008). "Anhydrous Neodymium(III) Acetate". Zeitschrift für anorganische und allgemeine Chemie. 634 (2): 231–233. doi:10.1002/zaac.200700407. ISSN 1521-3749.
^ "American elements - Neodymium acetate".
^ Perry, Dale L. (2016). Handbook of Inorganic Compounds (in German). CRC Press. p. 480. ISBN 978-1-4398-1462-8.
^ Holliday, A. K.; Massey, A. G. (2013). Non-Aqueous Solvents in Inorganic Chemistry (in German). Elsevier Science. p. 75. ISBN 978-1-4831-5941-6.
^ Mehrotra, R. C.; Misra, T. N.; Misra, S. N. Organic compounds of lanthanide elements: preparation of carboxylic acid salts of praseodymium and neodymium. Journal of the Indian Chemical Society, 1966. 1: 61-62. ISSN 0019-4522
^ Greenwood and Earnshaw, pp. 1248–9
^ Henderson, B.; Bartram, Ralph H. (2000). Crystal field engineering of solid state laser materials. Cambridge University Press. p. 211. ISBN 0-521-59349-2.
^ Kondrukevich, A.A., Vlasov, A.S., Platov, Y.T. et al. Color of porcelain containing neodymium oxide. Glass Ceram 65, 203–207 (2008). doi:10.1007/s10717-008-9039-9
^ Kuipers, Jeroen; Giepmans, Ben N. G. (1 April 2020). "Neodymium as an alternative contrast for uranium in electron microscopy". Histochemistry and Cell Biology. 153 (4): 271–277. doi:10.1007/s00418-020-01846-0. ISSN 1432-119X. PMC 7160090. PMID 32008069.
^ "Negative Staining" University of Oxford