Titanium tetraiodide

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Titanium tetraiodide
Titanium tetraiodide.png
IUPAC name
Titanium(IV) iodide
Other names
Titanium tetraiodide
3D model (JSmol)
ECHA InfoCard 100.028.868 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 231-754-0
PubChem CID
  • InChI=1S/4HI.Ti/h4*1H;/q;;;;+4/p-4 X mark.svgN
  • InChI=1/4HI.Ti/h4*1H;/q;;;;+4/p-4/rI4Ti/c1-5(2,3)4
  • [Ti](I)(I)(I)I
Molar mass 555.485 g/mol
Appearancered-brown crystals
Density 4.3 g/cm3
Melting point 150 °C (302 °F; 423 K)
Boiling point 377 °C (711 °F; 650 K)
Solubility in other solventssoluble in CH2Cl2
cubic (a = 12.21 Å)
0 D
Occupational safety and health (OHS/OSH):
Main hazards
violent hydrolysis
GHS labelling: [1]
P260, P264, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P363, P405, P501
Related compounds
Other anions
Titanium(IV) bromide
Titanium(IV) chloride
Titanium(IV) fluoride
Other cations
Silicon tetraiodide
Zirconium(IV) iodide
Hafnium(IV) iodide
Related compounds
Titanium(III) iodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Titanium tetraiodide is an inorganic compound with the formula TiI4. It is a black volatile solid, first reported by Rudolph Weber in 1863. [2] It is an intermediate in the van Arkel–de Boer process for the purification of titanium.


Physical properties

TiI4 is a rare molecular binary metal iodide, consisting of isolated molecules of tetrahedral Ti(IV) centers. The Ti-I distances are 261 pm. [3] Reflecting its molecular character, TiI4 can be distilled without decomposition at one atmosphere; this property is the basis of its use in the van Arkel–de Boer process. The difference in melting point between TiCl4 (m.p. -24 °C) and TiI4 (m.p. 150 °C) is comparable to the difference between the melting points of CCl4 (m.p. -23 °C) and CI4 (m.p. 168 °C), reflecting the stronger intermolecular van der Waals bonding in the iodides.

Two polymorphs of TiI4 exist, one of which is highly soluble in organic solvents. In the less soluble cubic form, the Ti-I distances are 261 pm. [3]


Three methods are well known: 1) From the elements, typically using a tube furnace at 425 °C: [4]

Ti + 2 I2 → TiI4

This reaction can be reversed to produce highly pure films of Ti metal. [5]

2) Exchange reaction from titanium tetrachloride and HI.

TiCl4 + 4 HI → TiI4 + 4 HCl

3) Oxide-iodide exchange from aluminium iodide.

3 TiO2 + 4 AlI3 → 3 TiI4 + 2 Al2O3


Like TiCl4 and TiBr4, TiI4 forms adducts with Lewis bases, and it can also be reduced. When the reduction is conducted in the presence of Ti metal, one obtains polymeric Ti(III) and Ti(II) derivatives such as CsTi2I7 and the chain CsTiI3, respectively. [6]

TiI4 exhibits extensive reactivity toward alkenes and alkynes resulting in organoiodine derivatives. It also effects pinacol couplings and other C-C bond-forming reactions. [7]

Related Research Articles

<span class="mw-page-title-main">Hafnium</span> Chemical element, symbol Hf and atomic number 72

Hafnium is a chemical element with the symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869, though it was not identified until 1923, by Dirk Coster and George de Hevesy, making it the penultimate stable element to be discovered. Hafnium is named after Hafnia, the Latin name for Copenhagen, where it was discovered.

<span class="mw-page-title-main">Titanium</span> Chemical element, symbol Ti and atomic number 22

Titanium is a chemical element with the symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in sea water, aqua regia, and chlorine.

<span class="mw-page-title-main">Group 4 element</span> Group of chemical elements

Group 4 is the second group of transition metals in the periodic table. It contains the four elements titanium (Ti), zirconium (Zr), hafnium (Hf), and rutherfordium (Rf). The group is also called the titanium group or titanium family after its lightest member.

<span class="mw-page-title-main">Lithium aluminium hydride</span> Chemical compound

Lithium aluminium hydride, commonly abbreviated to LAH, is an inorganic compound with the chemical formula Li[AlH4] or LiAlH4. It is a white solid, discovered by Finholt, Bond and Schlesinger in 1947. This compound is used as a reducing agent in organic synthesis, especially for the reduction of esters, carboxylic acids, and amides. The solid is dangerously reactive toward water, releasing gaseous hydrogen (H2). Some related derivatives have been discussed for hydrogen storage.

<span class="mw-page-title-main">Titanium tetrachloride</span> Inorganic chemical compound

Titanium tetrachloride is the inorganic compound with the formula TiCl4. It is an important intermediate in the production of titanium metal and the pigment titanium dioxide. TiCl4 is a volatile liquid. Upon contact with humid air, it forms thick clouds of titanium dioxide and hydrochloric acid, a reaction that was formerly exploited for use in smoke machines. It is sometimes referred to as "tickle" or "tickle 4" due to the phonetic resemblance of its molecular formula to the word.

The Kroll process is a pyrometallurgical industrial process used to produce metallic titanium from titanium tetrachloride. The Kroll process replaced the Hunter process for almost all commercial production.

<span class="mw-page-title-main">Van Arkel–de Boer process</span> Process for the commercial production of pure titanium and zirconium

The van Arkel–de Boer process, also known as the iodide process or crystal-bar process, was the first industrial process for the commercial production of pure ductile titanium, zirconium and some other metals. It was developed by Anton Eduard van Arkel and Jan Hendrik de Boer in 1925. Now it is used in the production of small quantities of ultrapure titanium and zirconium. It primarily involves the formation of the metal iodides and their subsequent decomposition to yield pure metal.

<span class="mw-page-title-main">Rhodium(III) chloride</span> Chemical compound

Rhodium(III) chloride refers to inorganic compounds with the formula RhCl3(H2O)n, where n varies from 0 to 3. These are diamagnetic solids featuring octahedral Rh(III) centres. Depending on the value of n, the material is either a dense brown solid or a soluble reddish salt. The soluble trihydrated (n = 3) salt is widely used to prepare compounds used in homogeneous catalysis, notably for the industrial production of acetic acid and hydroformylation.

<span class="mw-page-title-main">Titanocene dichloride</span> Chemical compound

Titanocene dichloride is the organotitanium compound with the formula (η5-C5H5)2TiCl2, commonly abbreviated as Cp2TiCl2. This metallocene is a common reagent in organometallic and organic synthesis. It exists as a bright red solid that slowly hydrolyzes in air. It shows antitumour activity and was the first non-platinum complex to undergo clinical trials as a chemotherapy drug.

Titanium(III) chloride is the inorganic compound with the formula TiCl3. At least four distinct species have this formula; additionally hydrated derivatives are known. TiCl3 is one of the most common halides of titanium and is an important catalyst for the manufacture of polyolefins.

<span class="mw-page-title-main">Carbon tetraiodide</span> Chemical compound

Carbon tetraiodide is a tetrahalomethane with the molecular formula CI4. Being bright red, it is a relatively rare example of a highly colored methane derivative. It is only 2.3% by weight carbon, although other methane derivatives are known with still less carbon.

<span class="mw-page-title-main">Zirconium(IV) iodide</span> Chemical compound

Zirconium(IV) iodide is the chemical compound with the formula ZrI4. It is the most readily available iodide of zirconium. It is an orange-coloured solid that degrades in the presence of water. The compound was once prominent as an intermediate in the purification of zirconium metal.

<span class="mw-page-title-main">Titanium tetrabromide</span> Chemical compound

Titanium tetrabromide is the chemical compound with the formula TiBr4. It is the most volatile transition metal bromide. The properties of TiBr4 are an average of TiCl4 and TiI4. Some key properties of these four-coordinated Ti(IV) species are their high Lewis acidity and their high solubility in nonpolar organic solvents. TiBr4 is diamagnetic, reflecting the d0 configuration of the metal centre.

Metal acetylacetonates are coordination complexes derived from the acetylacetonate anion (CH
) and metal ions, usually transition metals. The bidentate ligand acetylacetonate is often abbreviated acac. Typically both oxygen atoms bind to the metal to form a six-membered chelate ring. The simplest complexes have the formula M(acac)3 and M(acac)2. Mixed-ligand complexes, e.g. VO(acac)2, are also numerous. Variations of acetylacetonate have also been developed with myriad substituents in place of methyl (RCOCHCOR). Many such complexes are soluble in organic solvents, in contrast to the related metal halides. Because of these properties, acac complexes are sometimes used as catalyst precursors and reagents. Applications include their use as NMR "shift reagents" and as catalysts for organic synthesis, and precursors to industrial hydroformylation catalysts. C
in some cases also binds to metals through the central carbon atom; this bonding mode is more common for the third-row transition metals such as platinum(II) and iridium(III).

<span class="mw-page-title-main">Metal bis(trimethylsilyl)amides</span>

Metal bis(trimethylsilyl)amides are coordination complexes composed of a cationic metal with anionic bis(trimethylsilyl)amide ligands and are part of a broader category of metal amides.

<span class="mw-page-title-main">Metal halides</span>

Metal halides are compounds between metals and halogens. Some, such as sodium chloride are ionic, while others are covalently bonded. A few metal halides are discrete molecules, such as uranium hexafluoride, but most adopt polymeric structures, such as palladium chloride.

<span class="mw-page-title-main">(Cyclopentadienyl)titanium trichloride</span> Chemical compound

(Cyclopentadienyl)titanium trichloride is an organotitanium compound with the formula (C5H5)TiCl3. It is a moisture sensitive orange solid. The compound adopts a piano stool geometry.

<span class="mw-page-title-main">Titanium(II) iodide</span> Chemical compound

Titanium(II) iodide is the inorganic compound with the formula TiI2. It is a black micaceous solid. It adopts the cadmium iodide structure, featuring octahedral Ti(II) centers. It arises via the reaction of the elements:

The +4 oxidation state dominates titanium chemistry, but compounds in the +3 oxidation state are also numerous. Commonly, titanium adopts an octahedral coordination geometry in its complexes, but tetrahedral TiCl4 is a notable exception. Because of its high oxidation state, titanium(IV) compounds exhibit a high degree of covalent bonding.

Rhenium compounds are compounds formed by the transition metal rhenium (Re). Rhenium can form in many oxidation states, and compounds are known for every oxidation state from -3 to +7 except -2, although the oxidation states +7, +6, +4, and +2 are the most common. Rhenium is most available commercially as salts of perrhenate, including sodium and ammonium perrhenates. These are white, water-soluble compounds. Tetrathioperrhenate anion [ReS4] is possible.


  1. "Titanium tetraiodide". pubchem.ncbi.nlm.nih.gov. Retrieved 12 December 2021.
  2. Weber, R. (1863). "Ueber die isomeren Modificationen der Titansäure und über einige Titanverbindungen". Annalen der Physik . 120 (10): 287–294. Bibcode:1863AnP...196..287W. doi:10.1002/andp.18631961003.
  3. 1 2 Tornqvist, E. G. M.; Libby, W. F. (1979). "Crystal Structure, Solubility, and Electronic Spectrum of Titanium Tetraiodide". Inorganic Chemistry . 18 (7): 1792–1796. doi:10.1021/ic50197a013.
  4. Lowry, R. N.; Fay, R. C. (1967). Titanium(IV) Iodide. Inorganic Syntheses. Vol. 10. p. 1. doi:10.1002/9780470132418.ch1. ISBN   9780470132418.
  5. Blumenthal, W. B.; Smith, H. (1950). "Titanium tetraiodide, Preparation and Refining". Industrial and Engineering Chemistry . 42 (2): 249. doi:10.1021/ie50482a016.
  6. Jongen, L.; Gloger, T.; Beekhuizen, J.; Meyer, G. (2005). "Divalent Titanium: The Halides ATiX3 (A = K, Rb, Cs; X = Cl, Br, I)". Zeitschrift für anorganische und allgemeine Chemie . 631 (2–3): 582. doi:10.1002/zaac.200400464.
  7. Shimizu, M.; Hachiya, I. (2014). "Chemoselective Reductions and Iodinations using Titanium Tetraiodide". Tetrahedron Letters. 55 (17): 2781–2788. doi: 10.1016/j.tetlet.2014.03.052 .