Titanium tetraiodide

Template:Chembox header | Titanium tetraiodide
Titanium tetraiodide
Template:Chembox header | General
Systematic name	Titanium(IV) iodide
Other names	Titanium tetraiodide
Molecular formula	TiI4
SMILES	?
Molar mass	555.49 g/mol
Appearance	red-brown crystals
CAS number	[7720-83-4]
Template:Chembox header | Properties
Density and phase	4.3 g/cm3
Solubility in water	hydrolysis
Other solvents	CH2Cl2 CHCl3 CS2
Melting point	150 °C
Boiling point	377°C
Template:Chembox header | Structure
Coordination geometry	tetrahedral
Crystal structure	cubic (a = 12.21 Å)
Dipole moment	0 D
Template:Chembox header | Hazards
MSDS	External MSDS
Main hazards	violent hydrolysis corrosive
NFPA 704
R/S statement	R: 34-37 S: 26-36/37/39-45
RTECS number	?
Template:Chembox header | Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Template:Chembox header | Related compounds
Related ?	?
Related compounds	titanium tetrachloride, |titanium tetrabromide, carbon tetraiodide, I2
Template:Chembox header | Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Titanium tetraiodide is TiI₄. It is a rare molecular binary metal iodide, consisting of isolated molecules of tetrahedral Ti(IV) centers; the other example is Ta₂I₁₀. Reflecting its molecular character, TiI₄ can be distilled without decomposition at one atmosphere. The compound is a close relative to TiCl₄. 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.

Production

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

Ti + 2 I₂ → TiI₄

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

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

Reactions

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. As a solution in CH₂Cl₂, TiI₄ exhibits some reactivity toward alkenes and alkynes resulting in organoiodine derivatives.

References

• Blumenthal WB, Smith H (1950). "Titanium tetraiodide, Preparation and Refining". Industrial and Engenieering Chemistry. 2: 249. DOI
• Tornqvist EGM, Libby WF (1979). "Crystal Structure, Solubility, and Electronic Spectrum of Titanium Tetraiodide". Inorganic Chemistry. 18: 1792. DOI
• Lowery, R. N.; Fay, R. C. "Titanium(IV) Iodide" Inorganic Syntheses 1967, volume X, pages 1-6.
• Shimizu, Makoto; Toyoda, Tadahiro; Baba, Toru. An Intriguing Hydroiodination of Alkenes and Alkynes with Titanium Tetraiodide. Synlett 2005, volume 16, pages 2516-2518.
• Jongen, L.; Gloger, T.; Beekhuizen, J.; Meyer, G. "Divalent Titanium: The Halides ATiX₃ (A = K, Rb, Cs; X = Cl, Br, I)" Zeitschrift fur Anorganische und Allgemeine Chemie 2005, volume 631, pages 582-586.