Zirconium nitrate

Zirconium nitrate
Names
	Other names zirconium tetranitrate, tetranitratozirconium, zirconium(4+) tetranitrate, zirconium(IV) nitrate
Identifiers
CAS Number	13746-89-9 ;
3D model (JSmol)	Interactive image;
ChemSpider	24459 ;
ECHA InfoCard	100.033.917
PubChem CID	162478205;
UNII	L68X591SNQ ;
CompTox Dashboard (EPA)	DTXSID9049821 ;
	InChI InChI=1S/4NO3.Zr/c42-1(3)4;/q4-1;+4 Key: OERNJTNJEZOPIA-UHFFFAOYSA-N;
	SMILES [Zr+4].O=[N+]([O-])[O-].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O;
Properties
Chemical formula	Zr(NO3)4
Molar mass	339.243591 g/mol
Appearance	transparent plates
Melting point	°C
Boiling point	decompose 100 °C
Solubility in water	water, ethanol
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	oxidiser
	Lethal dose or concentration (LD, LC):
LCLo (lowest published)	500 mg/m3 (rat, 30 min)
Related compounds
Related compounds	Zirconyl nitrate, hafnium nitrate, titanium nitrate, zirconium perchlorate
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Zirconium nitrate is a volatile anhydrous transition metal nitrate salt of zirconium with formula Zr(NO₃)₄. It has alternate names of zirconium tetranitrate, or zirconium(IV) nitrate.

It has a UN number of UN 2728^[2] and is class 5.1, meaning oxidising substance.^[3]

Formation

The anhydrous salt can be made from zirconium tetrachloride reacting with dinitrogen pentoxide.^[4]

ZrCl₄ + 4 N₂O₅ → Zr(NO₃)₄ + 4ClNO₂

The product can be purified by sublimation in a vacuum. A contaminating substance in this is nitronium pentanitratozirconate. (NO₂)Zr(NO₃)₅.^[4]

Zirconium nitrate pentahydrate Zr(NO₃)₄·5H₂O can be formed by dissolving zirconium dioxide in nitric acid and then evaporating the solution until it is dry. However it is easier to crystallise zirconyl nitrate trihydrate ZrO(NO₃)₂·3H₂O from such a solution.^[4]

Zirconium is highly resistant to nitric acid even in the presence of other impurities and high temperatures.^[5] So zirconium nitrate is not made by dissolving zirconium metal in nitric acid.

Properties

Zirconium nitrate pentahydrate dissolves easily in water and alcohol. It is acidic in aqueous solution, and a base such as ammonium hydroxide will cause zirconium hydroxide to precipitate. The pentahydrate crystals have a refractive index of 1.6.^[6]

Related substances

Related substances are zirconium nitrate complexes. Zr(NO₃)₃(H₂O)+3 has a tricapped trigonal prismatic structure, with the nitrates connected by two oxygen atoms each (bidentate).^[4] The pentanitrato complex Zr(NO₃)−5 has all the nitrate groups bidentate, and has a bicapped square antiprism shape.^[4]

NO₂[Zr(NO₃)₃·3H₂O]₂(NO₃)₃ crystallizes in the hexagonal system, space group P3c1, with unit cell dimensions a = 10.292 Å, b = 10.292 Å, c = 14.84 Å, volume 1632.2 Å³ with 2 formulae per unit cell, density = 2.181.^[4]

CsZr(NO₃)₅ crystallizes in the monoclinic system, space group P2₁/n, with unit cell dimensions a = 7.497 Å, b = 11.567 Å, c = 14.411 Å, β=96.01°, volume 1242.8 Å³ with 4 formulae per cell, density = 2.855.^[4]

(NH₄)Zr(NO₃)₅·HNO₃ crystallizes in the orthorhombic system, space group Pna2₁ with unit cell dimensions a=14.852 Å, b = 7.222 Å, c = 13.177 Å, volume 1413.6 Å³ with 4 formulae per cell, density = 2.267.^[4]

A mixed nitronium, nitrosonium pentanitratozirconate crystallizing in the tetragonal system also exists.^[4]

Use

Zirconium nitrate is manufactured by a number of chemical suppliers. It is used as a source of zirconium for other salts,^[6] as an analytical standard,^[6] or as a preservative.^[6] Zirconium nitrate^[7] and nitronium pentanitratozirconate can be used as chemical vapour deposition precursors as they are volatile, and decompose above 100 °C to form zirconia.^[8] At 95 °C, zirconium nitrate sublimes with a pressure of 0.2 mm of Hg and can be deposited as zirconium dioxide on silicon at 285 °C. It has the advantage in that it is a single source, meaning it does not have to be mixed with other materials like oxygen, and decomposes at a relatively low temperature, and does not contaminate the surface with other elements such as hydrogen or fluorine.^[9]

Zirconium free from hafnium is required for nuclear reactor construction. One way to achieve this is via a mixed aqueous solution of hafnium nitrate and zirconium nitrate, which can be separated by partitioning the zirconium into tributylphosphate dissolved in kerosene.^[10]

Zirconium nitrate can be used as a Lewis acid catalyst in the formation of N-substituted pyrroles.^[11]

Anhydrous zirconium nitrate can nitrate some organic aromatic compounds in an unusual way. Quinoline is nitrated to 3-nitroquinoline and 7-nitroquinoline. Pyridine is nitrated to 3-nitropyridine and 4-nitropyridine.^[12]

References

^ "Zirconium compounds (as Zr)". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
^ "App A". The Code of Federal Regulations of the United States of America. U.S. Government Printing Office. 1988. p. 254.
^ Recommendations on the Transport of Dangerous Goods: Model Regulations. United Nations Publications. 2009. p. 430. ISBN 9789211391367.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Morozov, I. V.; A. A. Fedorova; D. V. Palamarchuk; S. I. Troyanov (2005). "Synthesis and crystal structures of zirconium(IV) nitrate complexes (NO2)[Zr(NO3)3(H2O)3]2(NO3) 3, Cs[Zr(NO3)5], and (NH4)[Zr(NO3)5](HNO3)". Russian Chemical Bulletin. 54 (1): 93–98. doi:10.1007/s11172-005-0222-7. ISSN 1066-5285. S2CID 97703681.
^ Wah Chang (10 September 2003). "Zirconium in Nitric Acid Applications" (PDF). Retrieved 13 October 2014.
^ ^a ^b ^c ^d Patnaik, Pradyot (2003). Handbook of inorganic chemicals. McGraw-Hill. p. 1000. ISBN 0070494398.
^ Fundamental Gas-phase and Surface Chemistry of Vapor-phase Deposition II and Process Control, Diagnostics and Modeling in Semiconductor Manufacturing IV: Proceedings of the International Symposium. The Electrochemical Society. 2001. p. 144. ISBN 9781566773195.
^ Nienow, Amanda M.; Jeffrey T. Roberts (2006). "Chemical Vapor Deposition of Zirconium Oxide on Aerosolized Silicon Nanoparticles". Chemistry of Materials. 18 (23): 5571–5577. doi:10.1021/cm060883e. ISSN 0897-4756.
^ Houssa, Michel (2003-12-01). High k Gate Dielectrics. CRC Press. pp. 73, 76–77. ISBN 9781420034141. Retrieved 17 October 2014.
^ Cox, R. P.; G. H. Beyer (23 December 1955). "Separation of Hafnium from Zirconium using Tributyl Phosphate". Retrieved 13 October 2014.
^ Hasaninejad, Alireza; Mohsen Shekouhy; Mohammad Reza Mohammadizadeh; Abdolkarim Zare (2012). "Zirconium nitrate: a reusable water tolerant Lewis acid catalyst for the synthesis of N-substituted pyrroles in aqueous media". RSC Advances. 2 (15): 6174. Bibcode:2012RSCAd...2.6174H. doi:10.1039/C2RA20294H. ISSN 2046-2069. registration required
^ Schofield, Kenneth (1980). Aromatic Nitration. CUP Archive. p. 97. ISBN 9780521233620. Retrieved 17 October 2014.