Thorium(IV) nitrate

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Thorium(IV) nitrate
Thorium(IV) nitrate.jpg
3D model (JSmol)
ECHA InfoCard 100.034.090 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • (anhydrous):237-514-1
PubChem CID
  • (anhydrous):InChI=1S/4NO3.Th/c4*2-1(3)4;/q4*-1;+4
  • (tetrahydrate):InChI=1S/4NO3.4H2O.Th/c4*2-1(3)4;;;;;/h;;;;4*1H2;/q4*-1;;;;;+4
  • (pentahydrate):InChI=1S/4NO3.5H2O.Th/c4*2-1(3)4;;;;;;/h;;;;5*1H2;/q4*-1;;;;;;+4
  • (hexahydrate):InChI=1S/4NO3.6H2O.Th/c4*2-1(3)4;;;;;;;/h;;;;6*1H2;/q4*-1;;;;;;;+4
  • (anhydrous):[N+](=O)([O-])[O-].[N+](=O)([O-])[O-].[N+](=O)([O-])[O-].[N+](=O)([O-])[O-].[Th+4]
  • (tetrahydrate):[N+](=O)([O-])[O-].[N+](=O)([O-])[O-].[N+](=O)([O-])[O-].[N+](=O)([O-])[O-].O.O.O.O.[Th+4]
  • (pentahydrate):[N+](=O)([O-])[O-].[N+](=O)([O-])[O-].[N+](=O)([O-])[O-].[N+](=O)([O-])[O-].O.O.O.O.O.[Th+4]
  • (hexahydrate):[N+](=O)([O-])[O-].[N+](=O)([O-])[O-].[N+](=O)([O-])[O-].[N+](=O)([O-])[O-].O.O.O.O.O.O.[Th+4]
Molar mass 480.066 (anhydrous)
552.130 (tetrahydrate)
570.146 (pentahydrate)
588.162 (hexahydrate)
AppearanceColorless crystal
Melting point 55 °C (131 °F; 328 K)
Boiling point Decomposes
Soluble [1]
GHS labelling:
GHS-pictogram-rondflam.svg GHS-pictogram-exclam.svg GHS-pictogram-silhouette.svg GHS-pictogram-pollu.svg
H272, H302, H315, H319, H335, H373, H411
P210, P220, P221, P260, P261, P264, P270, P271, P273, P280, P301+P312, P302+P352, P304+P340, P305+P351+P338, P312, P314, P321, P330, P332+P313, P337+P313, P362, P370+P378, P391, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Thorium(IV) nitrate used in a lamp. Gluestrumpf2.jpg
Thorium(IV) nitrate used in a lamp.

Thorium(IV) nitrate is a chemical compound with the formula Th(NO3)4. A white solid in its anhydrous form, it can form tetra- and pentahydrates. As a salt of thorium it is weakly radioactive.



Thorium(IV) nitrate hydrate can be prepared by the reaction of thorium(IV) hydroxide and nitric acid:

Th(OH)4 + 4 HNO3 + 3 H2O → Th(NO3)4•5H2O

Different hydrates are produced by crystallizing in different conditions. When a solution is very dilute, the nitrate is hydrolysed. Although various hydrates have been reported over the years, and some suppliers even claim to stock them, [2] only the tetrahydrate and pentahydrate actually exist. [3] What is called a hexahydrate, crystallized from a neutral solution, is probably a basic salt. [4]

The pentahydrate is the most common form. It is crystallized from dilute nitric acid solution. [5]

The tetrahydrate, Th(NO3)4•4H2O is formed by crystallizing from a stronger nitric acid solution. Concentrations of nitric acid from 4 to 59% result in the tetrahydrate forming. [3] The thorium atom has 12-coordination, with four bidentate nitrate groups and four water molecules attached to each thorium atom. [4]

To obtain the anhydrous thorium(IV) nitrate, thermal decomposition of Th(NO3)4·2N2O5 is required. The decomposition occurs at 150-160 °C. [6]


Anhydrous thorium nitrate is a white substance. It is covalently bound with low melting point of 55 °C. [3]

The pentahydrate Th(NO3)4•5H2O crystallizes with clear colourless crystals [7] in the orthorhombic system. The unit cell size is a=11.191 b=22.889 c=10.579 Å. Each thorium atom is connected twice to each of four bidentate nitrate groups, and to three water molecules via their oxygen atoms. In total the thorium is eleven-coordinated. There are also two other water molecules in the crystal structure. The water is hydrogen bonded to other water, or to nitrate groups. [8] The density is 2.80 g/cm3. [5] Vapour pressure of the pentahydrate at 298K is 0.7 torr, and increases to 1.2 torr at 315K, and at 341K it is up to 10.7 torr. At 298.15K the heat capacity is about 114.92 calK−1mol−1. This heat capacity shrinks greatly at cryogenic temperatures. Entropy of formation of thorium nitrate pentahydrate at 298.15K is −547.0 calK−1mol−1. The standard Gibbs energy of formation is −556.1 kcalmol−1. [9]

Thorium nitrate can dissolve in several different organic solvents [8] including alcohols, ketones, esters and ethers. [4] This can be used to separate different metals such as the lanthanides. With ammonium nitrate in the aqueous phase, thorium nitrate prefers the organic liquid, and the lanthanides stay with the water. [4]

Thorium nitrate dissolved in water lowers it freezing point. The maximum freezing point depression is −37 °C with a concentration of 2.9 mol/kg. [10]

At 25° a saturated solution of thorium nitrate contains 4.013 moles per liter. At this concentration the vapour pressure of water in the solution is 1745.2 Pascals, compared to 3167.2 Pa for pure water. [11]


When thorium nitrate pentahydrate is heated, nitrates with less water are produced, however the compounds also lose some nitrate. At 140 °C a basic nitrate, ThO(NO3)2 is produced. When strongly heated thorium dioxide is produced. [8]

A polymeric peroxynitrate is precipitated when hydrogen peroxide combines with thorium nitrate in solution with dilute nitric acid. Its formula is Th6(OO)10(NO3)4 •10H2O. [8]

The hydrolysis of thorium nitrate solutions produces basic nitrates Th2(OH)4(NO3)4xH2O and Th2(OH)2(NO3)6•8H2O. In crystals of Th2(OH)2(NO3).6•8H2O a pair of thorium atoms are connected by two bridging oxygen atoms. Each thorium atom is surrounded by three bidentate nitrate groups and three water molecules, bringing the coordination number to 11. [8]

When oxalic acid is added to a thorium nitrate solution, insoluble thorium oxalate precipitates. [12] Other organic acids added to thorium nitrate solution produce precipitates of organic salts with citric acid; basic salts, such as tartaric acid, adipic acid, malic acid, gluconic acid, phenylacetic acid, valeric acid. [13] Other precipitates are also formed from sebacic acid and azelaic acid

Double salts

Hexanitratothorates with the generic formula MI2Th(NO3)6 or MIITh(NO3)6•8H2O are made by mixing other metal nitrates with thorium nitrate in dilute nitric acid solution. MII can be Mg, Mn, Co, Ni, or Zn. MI can be Cs, (NO)+ or (NO2)+. [8] Crystals the divalent metal thorium hexanitrate octahydrate have a monoclinic form with similar unit cell dimensions: β=97°, a=9.08 b=8.75-8 c=12.61-3. [14] Pentanitratothorates with the generic formula MITh(NO3)5xH2O are known for MI being Na or K. [8]

K3Th(NO3)7 and K3H3Th(NO3)10•4H2O are also known [4]

Complexed salts

Thorium nitrate also crystallizes with other ligands and organic solvates including ethylene glycol diethyl ether, tri(n‐butyl)phosphate, butylamine, dimethylamine, trimethylphosphine oxide. [4]

Related Research Articles

Nitric acid, also known as aqua fortis and spirit of niter, is a highly corrosive mineral acid.

Monazite Mineral containing rare-earth elements

Monazite is a primarily reddish-brown phosphate mineral that contains rare-earth elements. Due to variability in composition, monazite is considered a group of minerals. The most common species of the group is monazite-(Ce), that is, the cerium-dominant member of the group. It occurs usually in small isolated crystals. It has a hardness of 5.0 to 5.5 on the Mohs scale of mineral hardness and is relatively dense, about 4.6 to 5.7 g/cm3. There are five different most common species of monazite, depending on the relative amounts of the rare earth elements in the mineral:

Copper(II) nitrate Chemical compound

Copper(II) nitrate describes any member of the family of inorganic compounds with the formula Cu(NO3)2(H2O)x. The hydrates are blue solids. Anhydrous copper nitrate forms blue-green crystals and sublimes in a vacuum at 150-200 °C. Common hydrates are the hemipentahydrate and trihydrate.

In chemistry, water(s) of crystallization or water(s) of hydration are water molecules that are present inside crystals. Water is often incorporated in the formation of crystals from aqueous solutions. In some contexts, water of crystallization is the total mass of water in a substance at a given temperature and is mostly present in a definite (stoichiometric) ratio. Classically, "water of crystallization" refers to water that is found in the crystalline framework of a metal complex or a salt, which is not directly bonded to the metal cation.

Cobalt(II) fluoride Chemical compound

Cobalt(II) fluoride is a chemical compound with the formula (CoF2). It is a pink crystalline solid compound which is antiferromagnetic at low temperatures (TN=37.7 K) The formula is given for both the red tetragonal crystal, (CoF2), and the tetrahydrate red orthogonal crystal, (CoF2·4H2O). CoF2 is used in oxygen-sensitive fields, namely metal production. In low concentrations, it has public health uses. CoF2 is sparingly soluble in water. The compound can be dissolved in warm mineral acid, and will decompose in boiling water. Yet the hydrate is water-soluble, especially the di-hydrate CoF2·2H2 O and tri-hydrate CoF2·3H2O forms of the compound. The hydrate will also decompose with heat.

Uranyl chloride Chemical compound

Uranyl chloride refers to inorganic compounds with the formula UO2Cl2(H2O)n where n = 0, 1, or 3. These are yellow-colored solids.

Indium(III) sulfate (In2(SO4)3) is a sulfate salt of the metal indium. It is a sesquisulfate, meaning that the sulfate group occurs 11/2 times as much as the metal. It may be formed by the reaction of indium, its oxide, or its carbonate with sulfuric acid. An excess of strong acid is required, otherwise insoluble basic salts are formed. As a solid indium sulfate can be anhydrous, or take the form of a pentahydrate with five water molecules or a nonahydrate with nine molecules of water. Indium sulfate is used in the production of indium or indium containing substances. Indium sulfate also can be found in basic salts, acidic salts or double salts including indium alum.

Iron(III) nitrate Chemical compound

Iron(III) nitrate, or ferric nitrate, is the name used for a series of inorganic compounds with the formula Fe(NO3)3.(H2O)n. Most common is the nonahydrate Fe(NO3)3.(H2O)9. The hydrates are all pale colored, water-soluble paramagnetic salts.

Nickel(II) nitrate Chemical compound

Nickel nitrate is the inorganic compound Ni(NO3)2 or any hydrate thereof. The anhydrous form is not commonly encountered, thus "nickel nitrate" usually refers to nickel(II) nitrate hexahydrate. The formula for this species is written in two ways: Ni(NO3)2.6H2O and, more descriptively [Ni(H2O)6](NO3)2. The latter formula indicates that the nickel(II) center is surrounded by six water molecules in this hydrated salt. In the hexahydrate, the nitrate anions are not bonded to nickel. Also known are three other hydrates: Ni(NO3)2.9H2O, Ni(NO3)2.4H2O, and Ni(NO3)2.2H2O. Anhydrous Ni(NO3)2 is also known.

Palladium(II) nitrate Chemical compound

Palladium(II) nitrate is the inorganic compound with the formula Pd(NO3)2.(H2O)x where x = 0 or 2. The anhydrous and dihydrate are deliquescent solids. According to X-ray crystallography, both compounds feature square planar Pd(II) with unidentate nitrate ligands. The anhydrous compound, which is a coordination polymer, is yellow.

Cobalt(II) nitrate Chemical compound

Cobalt nitrate is the inorganic compound with the formula Co(NO3)2.xH2O. It is cobalt(II)'s salt. The most common form is the hexahydrate Co(NO3)2·6H2O, which is a red-brown deliquescent salt that is soluble in water and other polar solvents.

Bismuth(III) nitrate Chemical compound

Bismuth(III) nitrate is a salt composed of bismuth in its cationic +3 oxidation state and nitrate anions. The most common solid form is the pentahydrate. It is used in the synthesis of other bismuth compounds. It is available commercially. It is the only nitrate salt formed by a group 15 element, indicative of bismuth's metallic nature.

Cerium nitrates Chemical compound

Cerium nitrate refers to a family of nitrates of cerium in the +3 or +4 oxidation state. Often these compounds contain water, hydroxide, or hydronium ions in addition to cerium and nitrate. Double nitrates of cerium also exist.

Zirconium nitrate Chemical compound

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.

Thorium compounds

Many compounds of thorium are known: this is because thorium and uranium are the most stable and accessible actinides and are the only actinides that can be studied safely and legally in bulk in a normal laboratory. As such, they have the best-known chemistry of the actinides, along with that of plutonium, as the self-heating and radiation from them is not enough to cause radiolysis of chemical bonds as it is for the other actinides. While the later actinides from americium onwards are predominantly trivalent and behave more similarly to the corresponding lanthanides, as one would expect from periodic trends, the early actinides up to plutonium have relativistically destabilised and hence delocalised 5f and 6d electrons that participate in chemistry in a similar way to the early transition metals of group 3 through 8: thus, all their valence electrons can participate in chemical reactions, although this is not common for neptunium and plutonium.

Plutonium(IV) nitrate Chemical compound

Plutonium (IV) nitrate is an inorganic compound, a salt of plutonium and nitric acid with the chemical formula Pu(NO3)4. The compound dissolves in water and forms crystalline hydrates as dark green crystals.

Dysprosium(III) nitrate Chemical compound

Dysprosium(III) nitrate is an inorganic compound, a salt of dysprosium and nitric acid with the chemical formula Dy(NO3)3. The compound forms yellowish crystals, dissolves in water, forms a crystalline hydrate.

Ytterbium(III) nitrate Chemical compound

Ytterbium (III) nitrate is an inorganic compound, a salt of ytterbium and nitric acid with the chemical formula Yb(NO3)3. The compound forms colorless crystals, dissolves in water, and also forms crystalline hydrates.

Thulium(III) nitrate Chemical compound

Thulium(III) nitrate is an inorganic compound, a salt of thulium and nitric acid with the chemical formula Tm(NO3)3. The compound forms dark-green crystals, readily soluble in water, also forms crystalline hydrates.

Transition metal nitrate complex Compound of nitrate ligands

A transition metal nitrate complex is a coordination compound containing one or more nitrate ligands. Such complexes are common starting reagents for the preparation of other compounds.


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  2. Bogus hydrates include 12, 6, 5.5, 2 and 1 water molecules.
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