Molybdenum tetrachloride

Chemical compound From Wikipedia, the free encyclopedia

Molybdenum tetrachloride is the inorganic compound with the empirical formula MoCl4. The material exists as two polymorphs, both being dark-colored paramagnetic solids. These compounds are mainly of interest as precursors to other molybdenum complexes.

Quick facts Names, Identifiers ...
Molybdenum tetrachloride
Molybdenum tetrachloride
Molybdenum tetrachloride
Names
IUPAC name
Molybdenum tetrachloride
Other names
Molybdenum(IV) chloride
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.033.039 Edit this at Wikidata
UNII
  • InChI=1S/4ClH.Mo/h4*1H;/q;;;;+4/p-4 X markN
    Key: OYMJNIHGVDEDFX-UHFFFAOYSA-J X markN
  • InChI=1/4ClH.Mo/h4*1H;/q;;;;+4/p-4/rCl4Mo/c1-5(2,3)4
    Key: OYMJNIHGVDEDFX-DFQGPNMMAB
  • Cl[Mo](Cl)(Cl)Cl
Properties
MoCl4
Molar mass 237.752 g/mol
Appearance black solid
Melting point 552 °C (1,026 °F; 825 K)
Decomposes
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
3
0
1
Flash point Non flammable
Related compounds
Related compounds
 Molybdenum(II) chloride
Molybdenum(III) chloride
Molybdenum(V) chloride
Molybdenum(VI) 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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Structure

Structure of β-MoCl4

The α polymorph is a polymer. The β polymorph is a hexamer. In both polymorph, the Mo center is octahedral with two terminal chloride ligands and four doubly bridging ligands.[1] In addition to these two binary phases, a number of adducts are known with the formula MoCl4L2 where L is a Lewis base.

Preparation

α-Molybdenum tetrachloride can be prepared from by dechlorination of molybdenum pentachloride using tetrachloroethene:[2]

2 MoCl5 + C2Cl4 → 2 MoCl4 + C2Cl6

Heating α-molybdenum tetrachloride in a sealed container in the presence of molybdenum pentachloride induces conversion to the β polymorph.[2]

Reactions

When heated in an open container, molybdenum tetrachloride evolves chlorine, giving molybdenum trichloride;[2]

2 MoCl4 → 2 MoCl3 + Cl2

The acetonitrile complex adduct can be prepared by reduction of the pentachloride with acetonitrile:[3][4]

2 MoCl5 + 5 CH3CN → 2 MoCl4(CH3CN)2 + ClCH2CN + HCl

The MeCN ligands can be exchanged with other ligands:

MoCl4(CH3CN)2 + 2 THF → MoCl4(THF)2 + 2 CH3CN

The pentachloride can be reduced to the ether complex MoCl4(Et2O)2 using tin powder. It is a beige, paramagnetic solid.[5]

References

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