Mercury(II) perchlorate
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CAS Number
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3D model (JSmol)
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| ECHA InfoCard | 100.028.659 |
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PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |
Chemical formula
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Hg(ClO4)2 |
| Molar mass | 399.49 g/mol (anhydrous) |
| Appearance | White solid |
| Density | 2.84 g/cm3 (hexahydrate)[1] |
| Melting point | 170 °C (338 °F; 443 K)[2] (anhydrous) |
| Boiling point | 250 °C (482 °F; 523 K)[2] (decomposition, anhydrous) |
Solubility in water
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Soluble |
| Structure[1] | |
Crystal structure
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Trigonal (hexahydrate) |
Space group
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P3m1 (hexahydrate) |
Lattice constant
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a = 8.01 Å, b = 8.01 Å, c = 5.34 Å α = 90°, β = 90°, γ = 120° (hexahydrate)
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| NFPA 704 (fire diamond) | 
4
0
0 OX |
Threshold limit value (TLV)
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0.05 mg/m3 (TWA), 0.1 mg/m3 (C) |
| NIOSH (US health exposure limits): | |
IDLH (Immediate danger)
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10 mg/m3 |
| Related compounds | |
Other cations
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Cadmium perchlorate |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
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Mercury(II) perchlorate is an inorganic chemical compound with the formula Hg(ClO4)2·nH2O, where n can range from 0 to 6. The anhydrous and hydrates are all toxic, water-soluble, and hygroscopic white solids.[2][1]
Preparation and reactions
Hydrates of mercury(II) perchlorate are most commonly prepared by the reaction of mercury(II) oxide and concentrated perchloric acid:[1]
- HgO + 2 HClO4 → Hg(ClO4)2 + H2O
Evaporation of the resulting solution results in the formation of the hexahydrate, Hg(ClO4)2·6H2O, which can be converted to lower hydrates, such as the dihydrate, by heating to 30 °C in a vacuum. Further heating does not produce the anhydrous form, but instead forms a basic mercury perchlorate.[2][1]
The anhydrous form is produced by dehydrating the dihydrate with anhydrous perchloric acid or dichlorine hexoxide.[2][3]
Solutions of mercury(II) perchlorate in water reacts with aqueous ammonia to produce tetraamminemercury(II) perchlorate, [Hg(NH3)4](ClO4)2. Heating of the tetraammine complex results in the diammine complex.[4]
Mercury(II) perchlorate also reacts with elemental mercury to form mercury(I) perchlorate:[2][5]
- Hg(ClO4)2 + Hg → Hg2(ClO4)2
Structure
The solid hexahydrate, Hg(ClO4)2·6H2O, has a trigonal crystal structure and consists of octahederal [Hg(H2O)6]2+ centers and ClO4– ions.[1]
The anhydrous form was probed by IR spectroscopy and was found to consist of monodendate perchlorate ions.[3]
Applications
Mercury(II) perchlorate finds limited applications in organic synthesis, such as in the hydrolysis of vinyl halides and the allylation of isatins and isatin ketoimines.[6][7]
References
- ^ a b c d e f Johansson, Georg; Sandström, Magnus; Mosbæk, H.; Søtofte, I.; Smidsrød, Olav; Pontchour, Cha-On; Phavanantha, Pathana; Pramatus, Supanich; Cyvin, Bjørg N.; Cyvin, Sven J. (1978). "The Crystal Structure of Hexaaquamercury(II) Perchlorate, [Hg(H2O)6](ClO4)2". Acta Chemica Scandinavica. 32a: 109–113. doi:10.3891/acta.chem.scand.32a-0109. ISSN 0904-213X.
- ^ a b c d e f Z. K. Nikitina; V. Ya. Rosolovskii (1986). "Anhydrous Mercury(I) and Mercury(II) Perchlorates". Russian Journal of Inorganic Chemistry. 31 (11): 1682–1685.
- ^ a b Fourati, Mohieddine; Chaabouni, Moncef; Pascal, Jean-Louis; Potier, Jacqueline (1987-12-01). "Réactivité du trioxyde de chlore avec des chlorures, des nitrates, des carbonates et des perchlorates hydratés. Synthèse et analyse structurale de complexes de Cd(II) et Hg(II): Cd(ClO4)2, Hg(ClO4)2, ClO2Cd(ClO4)3, NO2Cd(ClO4)3, (NO2)2Hg(ClO4)4 et HgClClO4". Canadian Journal of Chemistry. 65 (12): 2783–2790. doi:10.1139/v87-463. ISSN 0008-4042. Retrieved 2025-10-03.
- ^ Nilsson, Kersti B.; Maliarik, Mikhail; Persson, Ingmar; Fischer, Andreas; Ullström, Ann-Sofi; Eriksson, Lars; Sandström, Magnus (2008). "Coordination Chemistry of Mercury(II) in Liquid and Aqueous Ammonia Solution and the Crystal Structure of Tetraamminemercury(II) Perchlorate". Inorganic Chemistry. 47 (6): 1953–1964. doi:10.1021/ic7013489. ISSN 0020-1669.
- ^ Wickleder, Mathias S. (2002). "(Hg2)Hg(OH)2(ClO4)2: Das erste gemischtvalente QuecksilberperchloratProfessor Welf Bronger zum 70. Geburtstag gewidmet". Zeitschrift für anorganische und allgemeine Chemie. 628 (7): 1459–1460. doi:10.1002/1521-3749(200207)628:7<1459::AID-ZAAC1459>3.0.CO;2-C.
- ^ Kočovský, Pavel (2001). "Mercury(II) Perchlorate". Encyclopedia of Reagents for Organic Synthesis. Chichester, UK: John Wiley & Sons, Ltd. doi:10.1002/047084289x.rm042. ISBN 978-0-471-93623-7.
- ^ Cao, Zhong-Yan; Zhang, Yan; Ji, Cong-Bin; Zhou, Jian (2011). "A Hg(ClO4)2·3H2O Catalyzed Sakurai–Hosomi Allylation of Isatins and Isatin Ketoimines Using Allyltrimethylsilane". Organic Letters. 13 (24): 6398–6401. doi:10.1021/ol202705g. ISSN 1523-7060.