Titanium(III) chloride

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Titanium(III) chloride
β-TiCl3 viewed along the chains
TiCl3 solution
Names
Other names
titanium trichloride
titanous chloride
Identifiers
3D model (
JSmol
)
ChemSpider
ECHA InfoCard
 100.028.845 Edit this at Wikidata
EC Number
  • 231-728-9
RTECS number
  • XR1924000
UNII
  • InChI=1S/3ClH.Ti/h3*1H;/q;;;+3/p-3 checkY
    Key: YONPGGFAJWQGJC-UHFFFAOYSA-K checkY
  • 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
Appearance red-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).
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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.

Structure and bonding

In TiCl3, each titanium atom has one d electron, rendering its derivatives

Laporte selection rule
.

Four solid forms or

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

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]

References

  1. ^
    OCLC 29029713
    .
  2. ISBN 978-0-08-037941-8
    .
  3. ISBN 978-0-08-037941-8
    .
  4. ISBN 978-0-470-13237-1
    .
  5. doi:10.1021/om060486d
    .
  6. doi:10.1107/S056774088100438X
    .
  7. ISBN 978-0-471-86520-9
    .
  8. S2CID 99668641
    .
  9. ISBN 0-12-352651-5.[page needed
    ]
  10. doi:10.1002/(SICI)1521-3749(200004)626:4<822::AID-ZAAC822>3.0.CO;2-6
    .
  11. doi:10.1002/zaac.200300315
    .
  12. ISBN 978-3527306732
    .
  13. ISBN 978-0-471-93623-7
    .
  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. doi:10.15227/orgsyn.060.0113
    .
  16. ISSN 0008-4042
    .
  17. ISBN 978-0-470-52330-8
    .
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