Titanium(III) chloride

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Titanium(III) chloride
Beta-TiCl3-chain-from-xtal-3D-balls.png
Beta-TiCl3-chains-packing-from-xtal-3D-balls-B.png
β-TiCl3 viewed along the chains
TiCl3.jpg
TiCl3 solution
Names
Other names
titanium trichloride
titanous chloride
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.028.845 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 231-728-9
PubChem CID
RTECS number
  • XR1924000
UNII
  • InChI=1S/3ClH.Ti/h3*1H;/q;;;+3/p-3 Yes check.svgY
    Key: YONPGGFAJWQGJC-UHFFFAOYSA-K Yes check.svgY
  • InChI=1/3ClH.Ti/h3*1H;/q;;;+3/p-3
    Key: YONPGGFAJWQGJC-DFZHHIFOAS
  • Cl[Ti](Cl)Cl
Properties
TiCl3
Molar mass 154.225 g/mol
Appearancered-violet crystals
hygroscopic
Density 2.64 g/cm3 [1]
Melting point 440 °C (824 °F; 713 K) (decomposes) [1]
very soluble
Solubility soluble in acetone, acetonitrile, certain amines;
insoluble in ether and hydrocarbons
+1110.0×10−6 cm3/mol
1.4856
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
Corrosive
Safety data sheet (SDS) External MSDS
Related compounds
Other anions
Titanium(III) fluoride
Titanium(III) bromide
Titanium(III) iodide
Other cations
Scandium(III) chloride
Chromium(III) chloride
Vanadium(III) chloride
Related compounds
 Titanium(IV) chloride
Titanium(II) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

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.

Contents

Structure and bonding

In TiCl3, each titanium atom has one d electron, rendering its derivatives paramagnetic, that is, the substance is attracted into a magnetic field. Solutions of titanium(III) chloride are violet, which arises from excitations of its d-electron. The colour is not very intense since the transition is forbidden by the Laporte selection rule.

Four solid forms or polymorphs of TiCl3 are known. All feature titanium in an octahedral coordination sphere. These forms can be distinguished by crystallography as well as by their magnetic properties, which probes exchange interactions. β-TiCl3 crystallizes as brown needles. Its structure consists of chains of TiCl6 octahedra that share opposite faces such that the closest Ti–Ti contact is 2.91 Å. This short distance indicates strong metal–metal interactions (see figure in upper right). The three violet "layered" forms, named for their color and their tendency to flake, are called alpha (α), gamma (γ), and delta (δ). In α-TiCl3, the chloride anions are hexagonal close-packed. In γ-TiCl3, the chlorides anions are cubic close-packed. Finally, disorder in shift successions, causes an intermediate between alpha and gamma structures, called the δ form. The TiCl6 share edges in each form, with 3.60 Å being the shortest distance between the titanium cations. This large distance between titanium cations precludes direct metal-metal bonding. In contrast, the trihalides of the heavier metals hafnium and zirconium engage in metal-metal bonding. Direct Zr–Zr bonding is indicated in zirconium(III) chloride. The difference between the Zr(III) and Ti(III) materials is attributed in part to the relative radii of these metal centers. [2]

Two hydrates of titanium(III) chloride are known, i.e. complexes containing aquo ligands. These include the pair of hydration isomers [Ti(H2O)6]Cl3 and [Ti(H2O)4Cl2]Cl(H2O)2. The former is violet and the latter, with two molecules of water of crystallization, is green. [3]

Synthesis and reactivity

TiCl3 is produced usually by reduction of titanium(IV) chloride. Older reduction methods used hydrogen: [4]

2 TiCl4 + H2 → 2 HCl + 2 TiCl3

It can also be produced by the reaction of titanium metal and hydrochloric acid.

It is conveniently reduced with aluminium and sold as a mixture with aluminium trichloride, TiCl3·AlCl3. This mixture can be separated to afford TiCl3(THF)3. [5] The complex adopts a meridional structure. [6] This light-blue complex TiCl3(THF)3 forms when TiCl3 is treated with tetrahydrofuran (THF). [7]

TiCl3 + 3 C4H8O → TiCl3(OC4H8)3

An analogous dark green complex arises from complexation with dimethylamine. In a reaction where all ligands are exchanged, TiCl3 is a precursor to the blue-colored complex Ti(acac)3. [8]

The more reduced titanium(II) chloride is prepared by the thermal disproportionation of TiCl3 at 500 °C. The reaction is driven by the loss of volatile TiCl4: [9]

2 TiCl3 → TiCl2 + TiCl4

The ternary halides, such as A3TiCl6, have structures that depend on the cation (A+) added. [10] Caesium chloride treated with titanium(II) chloride and hexachlorobenzene produces crystalline CsTi2Cl7. In these structures Ti3+ exhibits octahedral coordination geometry. [11]

Applications

TiCl3 is the main Ziegler–Natta catalyst, responsible for most industrial production of polyethylene. The catalytic activities depend strongly on the polymorph of the TiCl3 (α vs. β vs. γ vs. δ) and the method of preparation. [12]

Laboratory use

TiCl3 is also a specialized reagent in organic synthesis, useful for reductive coupling reactions, often in the presence of added reducing agents such as zinc. It reduces oximes to imines. [13] Titanium trichloride can reduce nitrate to ammonium ion thereby allowing for the sequential analysis of nitrate and ammonia. [14] Slow deterioration occurs in air-exposed titanium trichloride, often resulting in erratic results, such as in reductive coupling reactions. [15]

Safety

TiCl3 and most of its complexes are typically handled under air-free conditions to prevent reactions with oxygen and moisture. Samples of TiCl3 can be relatively air stable or pyrophoric. [16] [17]

Related Research Articles

<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.

<span class="mw-page-title-main">Aluminium chloride</span> Chemical compound

Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula AlCl3. It forms a hexahydrate with the formula [Al(H2O)6]Cl3, containing six water molecules of hydration. Both the anhydrous form and the hexahydrate are colourless crystals, but samples are often contaminated with iron(III) chloride, giving them a yellow colour.

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

Iron(II) chloride, also known as ferrous chloride, is the chemical compound of formula FeCl2. It is a paramagnetic solid with a high melting point. The compound is white, but typical samples are often off-white. FeCl2 crystallizes from water as the greenish tetrahydrate, which is the form that is most commonly encountered in commerce and the laboratory. There is also a dihydrate. The compound is highly soluble in water, giving pale green solutions.

<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">Scandium chloride</span> Chemical compound

Scandium(III) chloride is the inorganic compound with the formula ScCl3. It is a white, high-melting ionic compound, which is deliquescent and highly water-soluble. This salt is mainly of interest in the research laboratory. Both the anhydrous form and hexahydrate (ScCl3•6H2O) are commercially available.

<span class="mw-page-title-main">Hafnium tetrachloride</span> Chemical compound

Hafnium(IV) chloride is the inorganic compound with the formula HfCl4. This colourless solid is the precursor to most hafnium organometallic compounds. It has a variety of highly specialized applications, mainly in materials science and as a catalyst.

<span class="mw-page-title-main">McMurry reaction</span>

The McMurry reaction is an organic reaction in which two ketone or aldehyde groups are coupled to form an alkene using a titanium chloride compound such as titanium(III) chloride and a reducing agent. The reaction is named after its co-discoverer, John E. McMurry. The McMurry reaction originally involved the use of a mixture TiCl3 and LiAlH4, which produces the active reagents. Related species have been developed involving the combination of TiCl3 or TiCl4 with various other reducing agents, including potassium, zinc, and magnesium. This reaction is related to the Pinacol coupling reaction which also proceeds by reductive coupling of carbonyl compounds.

<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.

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

Zirconium(IV) chloride, also known as zirconium tetrachloride, is an inorganic compound frequently used as a precursor to other compounds of zirconium. This white high-melting solid hydrolyzes rapidly in humid air.

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

Vanadium(III) chloride is the inorganic compound with the formula VCl3 which forms the hexahydrate, [VCl2(H2O)4]Cl·2H2O. This hygroscopic purple salt is a common precursor to other vanadium(III) complexes.

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

Molybdenum(V) chloride is the inorganic compound with the empirical formula MoCl5. This dark volatile solid is used in research to prepare other molybdenum compounds. It is moisture-sensitive and soluble in chlorinated solvents.

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

Zirconium(III) chloride is an inorganic compound with formula ZrCl3. It is a blue-black solid that is highly sensitive to air.

<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">Molybdenum(III) chloride</span> Chemical compound

Molybdenum(III) chloride is the inorganic compound with the formula MoCl3. It forms purple crystals.

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

Bis(cyclopentadienyl)titanium(III) chloride, also known as the Nugent–RajanBabu reagent, is the organotitanium compound which exists as a dimer with the formula [(C5H5)2TiCl]2. It is an air sensitive green solid. The complex finds specialized use in synthetic organic chemistry as a single electron reductant.

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

Tantalum(III) chloride or tantalum trichloride is non-stoichiometric chemical compound with a range of composition from TaCl2.9 to TaCl3.1 Anionic and neutral clusters containing Ta(III) chloride include [Ta6Cl18]4− and [Ta6Cl14](H2O)4.

A chloride nitride is a mixed anion compound containing both chloride (Cl−) and nitride ions (N3−). Another name is metallochloronitrides. They are a subclass of halide nitrides or pnictide halides.

<span class="mw-page-title-main">Transition metal ether complex</span>

In chemistry, a transition metal ether complex is a coordination complex consisting of a transition metal bonded to one or more ether ligand. The inventory of complexes is extensive. Common ether ligands are diethyl ether and tetrahydrofuran. Common chelating ether ligands include the glymes, dimethoxyethane (dme) and diglyme, and the crown ethers. Being lipophilic, metal-ether complexes often exhibit solubility in organic solvents, a property of interest in synthetic chemistry. In contrast, the di-ether 1,4-dioxane is generally a bridging ligand.

Manganese(III) chloride is the hypothetical inorganic compound with the formula MnCl3.

References

  1. 1 2 Eagleson, Mary (1994). Concise encyclopedia chemistry. Berlin: Walter de Gruyter. ISBN   0-89925-457-8. OCLC   29029713.
  2. ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN   978-0-08-037941-8.
  3. ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 965. ISBN   978-0-08-037941-8.
  4. ↑ Sherfey, J. M. (2007). "Titanium(III) Chloride and Titanium(III) Bromide". Inorganic Syntheses. Inorganic Syntheses. Vol. 6. pp. 57–61. doi:10.1002/9780470132371.ch17. ISBN   9780470132371.
  5. ↑ Jones, N. A.; Liddle, S. T.; Wilson, C.; Arnold, P. L. (2007). "Titanium(III) Alkoxy-N-heterocyclic Carbenes and a Safe, Low-Cost Route to TiCl3(THF)3". Organometallics. 26 (3): 755–757. doi:10.1021/om060486d.
  6. ↑ Handlovic, M.; Miklos, D.; Zikmund, M. (1981). "The structure of trichlorotris(tetrahydrofuran)titanium(III)". Acta Crystallographica B. 37 (4): 811–814. doi:10.1107/S056774088100438X.
  7. ↑ Manzer, L. E. (1982). "Tetrahydrofuran Complexes of Selected Early Transition Metals". Inorganic Syntheses . 21: 137. doi:10.1002/9780470132524.ch31.
  8. ↑ Arslan, Evrim; Lalancette, Roger A.; Bernal, Ivan (2017). "An Historic and Scientific Study of the Properties of Metal(III) Tris-acetylacetonates". Structural Chemistry. 28: 201–212. doi:10.1007/s11224-016-0864-0. S2CID   99668641.
  9. ↑ Holleman, A. F.; Wiberg, E. (2001). Inorganic Chemistry. San Diego, CA: Academic Press. ISBN   0-12-352651-5.[ page needed ]
  10. ↑ Hinz, D.; Gloger, T.; Meyer, G. (2000). "Ternary halides of the type A3MX6. Part 9. Crystal structures of Na3TiCl6 and K3TiCl6". Zeitschrift für Anorganische und Allgemeine Chemie. 626 (4): 822–824. doi:10.1002/(SICI)1521-3749(200004)626:4<822::AID-ZAAC822>3.0.CO;2-6.
  11. ↑ Jongen, L.; Meyer, G. (2004). "Caesium heptaiododititanate(III), CsTi2I7". Zeitschrift für Anorganische und Allgemeine Chemie. 630 (2): 211–212. doi:10.1002/zaac.200300315.
  12. ↑ Whiteley, Kenneth S.; Heggs, T. Geoffrey; Koch; Mawer, Ralph L.; Immel, Wolfgang (2005). "Polyolefins". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a21_487.
  13. ↑ Gundersen, Lise-Lotte; Rise, Frode; Undheim, Kjell; Méndez Andino, José (2007). "Titanium(III) Chloride". Encyclopedia of Reagents for Organic Synthesis . doi:10.1002/047084289X.rt120.pub2. ISBN   978-0471936237.
  14. ↑ Rich, D. W.; Grigg, B.; Snyder, G. H. (2006). "Determining Ammonium & Nitrate ions using a Gas Sensing Ammonia Electrode". Soil and Crop Science Society of Florida. 65.
  15. ↑ Fleming, Michael P.; McMurry, John E. (1981). "Reductive Coupling of Carbonyls to Alkenes: Adamantylideneadamantane". Organic Syntheses . 60: 113. doi:10.15227/orgsyn.060.0113.
  16. ↑ Ingraham, T. R.; Downes, K. W.; Marier, P. (1957). "The Production of Titanium Trichloride by Arc-Induced Hydrogen Reduction of Titanium Tetrachloride". Canadian Journal of Chemistry. 35 (8): 850–872. doi:10.1139/v57-118. ISSN   0008-4042.
  17. ↑ Pohanish, Richard P.; Greene, Stanley A. (2009). Wiley Guide to Chemical Incompatibilities (3rd ed.). John Wiley & Sons. p. 1010. ISBN   9780470523308.
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