Hafnium(IV) sulfate

Hafnium(IV) sulfate

Names
Other names Hafnium disulfate
Identifiers
CAS Number	15823-43-5
3D model (JSmol)	Interactive image tetrahydrate: Interactive image
ChemSpider	16019775
PubChem CID	13094115
CompTox Dashboard (EPA)	DTXSID40890765
InChI InChI=1S/Hf.2H2O4S/c;2*1-5(2,3)4/h;2*(H2,1,2,3,4)/q+4;;/p-4 Key: NXKAMHRHVYEHER-UHFFFAOYSA-J
SMILES [O-]S(=O)(=O)[O-].[O-]S(=O)(=O)[O-].[Hf+4] tetrahydrate: [O-]S(=O)(=O)[O-].[O-]S(=O)(=O)[O-].[Hf+4].O.O.O.O
Properties
Chemical formula	Hf(SO4)2
Molar mass	370.62 g/mol (anhydrous)
Appearance	White solid[1]
Density	4.86 g/cm^3[1]
Melting point	350 °C (662 °F; 623 K)[2] (decomposition)
Solubility in water	Soluble[1]
Structure
Crystal structure	Orthorhombic[1]
Coordination geometry	8 (hafnium)[1]
Related compounds
Other anions	Hafnium(IV) nitrate
Other cations	Zirconium(IV) sulfate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Hafnium(IV) sulfate is describes the inorganic chemical compounds with the formula Hf(SO₄)₂·nH₂O, where n can range from 0 to 7. It commonly forms the anhydrous and tetrahydrate forms, which are both white solids.[1]

Structure

Anhydrous hafnium(IV) sulfate consists of a polymeric network of sulfate-bridged hafnium atoms. It is isomorphous with zirconium(IV) sulfate.[1]

Hafnium(IV) sulfate tetrahydrate is isomorphous with zirconium(IV) sulfate tetrahydrate and consists of repeated sheets of Hf(SO₄)₂(H₂O)₄, where the sulfate ligands are bidentate.[1]

Preparation and properties

The tetrahydrate is produced by the reaction of hafnium metal or hafnium(IV) oxide with concentrated sulfuric acid followed by evaporation of the solution:[1]

Hf + 2 H₂SO₄ → Hf(SO₄)₂ + 2 H₂

The anhydrous form can be produced by heating the tetrahydrate to 350 °C. If the anhydrous is heated to 820 °C, it decomposes to hafnium(IV) oxide, sulfur oxides, and oxygen. The mechanism of decomposition has not been fully elucidated.[2]

Various hydrolyzed derivatives of hafnium(IV) oxide, such as [Hf₁₈O₁₀(OH)₂₆(SO₄)_12.7(H₂O)₂₀]Cl_0.6·nH₂O are known.[3]

References

1. I.J. Bear; W.G. Mumme (1970). "The preparation and characterization of phases in the Hf(SO4)2H2O system". Journal of Inorganic and Nuclear Chemistry. 32 (4): 1159–1164. doi:10.1016/0022-1902(70)80110-5.
2. H.A. Papazian; P.J. Pizzolato; R.R. Orrell (1972). "The Thermal Decomposition of Aluminum Sulfate and Hafnium Sulfate". Thermochimica Acta. 4 (2): 97–103. Bibcode:1972TcAc....4...97P. doi:10.1016/S0040-6031(72)80023-6.
3. Ali Kalaji; L. Soderholm (2014). "Aqueous Hafnium Sulfate Chemistry: Structures of Crystalline Precipitates". Inorganic Chemistry. 53 (20): 11252–11260. doi:10.1021/ic501841e. PMID 25299984.