Holmium acetate explained

Holmium acetate is the acetate salt of holmium, with a chemical formula of Ho(CH₃COO)₃.

Preparation

Holmium acetate can be obtained by dissolving holmium oxide in hot acetic acid

Ho₂(O₃ + 6 CH₃CO₂H → 2 Ho(O₂CH₃)₃ + 3 H₂O

Dissolving holmium oxide in acetic acid at a pH of 4 will form the tetrahydrate of holmium acetate (Ho₂(CH₃COO)₆·4H₂O):^[1] The anhydrous material can be obtained by heating the hydrated acetate in acetic acid.

Physical properties and structure

Holmium acetate hemihepthydate decomposes at 105 °C, forming into a hemihydrate, further decomposing at 135 °C into an anhydride. Further adding heat will form Ho(OH)(CH₃COO)₂, HoO(CH₃COO) then Ho₂O₂CO₃, forming holmium oxide at 590 °C.^[2]

According to X-ray crystallography, anhydrous holmium acetate is a coordination polymer. Each Ho(III) center is nine-coordinate, with two bidentate acetate ligands and the remaining sites occupied by oxygens provided by bridging acetate ligands. The lanthanum and praseodymium compounds are isostructural.^[3] In a second polymorph, holmium acetate has 8-coordination.^[4]

Applications

Holmium acetate is used in the manufacture of ceramics, glass, phosphors, metal halide lamps, and as a dopant in garnet lasers. It is also used in nuclear reactors to keep the chain reaction in check.^[5]

External reading

• Acetate Complexes of the Rare Earth and Several Transition Metal Ions. 1962-05-01. 10.1021/ic50002a019. Inorganic Chemistry. 293–296. 1. 2. 0020-1669. R. S. Kolat, J. E. Powell.

Notes and References

1. Spectral intensities of holmium acetate single crystals. 186. 1. 135–138. 1991-08-01. 0020-1693. 10.1016/S0020-1693(00)87943-8. Inorganica Chimica Acta. Anna Mondry, Krystyna Bukietyńska.
2. Holmium oxide from holmium acetate, formation and characterization: thermoanalytical studies. 56. 2. 263–272. 2000-11-01. 0165-2370. 10.1016/S0165-2370(00)00100-5. Journal of Analytical and Applied Pyrolysis. G. A. M. Hussein, B. A. A. Balboul, G. A. H. Mekhemer. 2000JAAP...56..263H .
3. 10.1002/zaac.19946200306 . 1994 . 620 . 3 . Lossin . Adalbert . Meyer . Gerd . Pr(CH₃COO)₃, ein wasserfreies Selten-Erd-Acetat mit Netzwerkstruktur . Zeitschrift für Anorganische und Allgemeine Chemie .
4. 10.1002/zaac.19936190917 . 1993 . 619 . 9 . Lossin . Adalbert . Meyer . Gerd . Wasserfreie Selten-Erd-Acetate, M(CH₃COO)₃ (M = Sm-Lu, Y) mit Kettenstruktur. Kristallstrukturen von Lu(CH₃COO)₃ und Ho(CH₃COO)₃ . Zeitschrift für Anorganische und Allgemeine Chemie .
5. Web site: 2014-01-01. Holmium acetate.