Molybdenum(V) chloride

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Molybdenum(V) chloride
Molybdenum(V) chloride
Ball-and-stick model of the Mo2Cl10 molecule in the crystal structure

Partially oxidized MoCl5
Names
IUPAC names
Molybdenum(V) chloride
Molybdenum pentachloride
Identifiers
3D model (
JSmol
)
ECHA InfoCard
 100.030.510 Edit this at Wikidata
EC Number
  • 233-575-3
RTECS number
  • QA4690000
UNII
  • InChI=1S/5ClH.Mo/h5*1H;/q;;;;;+5/p-5
  • InChI=1S/10ClH.2Mo/h10*1H;;/q;;;;;;;;;;2*+4/p-8
  • Cl[Mo](Cl)(Cl)(Cl)Cl
  • Cl1[Mo](Cl)(Cl)(Cl)(Cl)Cl[Mo]1(Cl)(Cl)(Cl)Cl
Properties
Mo2Cl10
Molar mass 273.21 g/mol (MoCl5)
Appearance dark-green solid
paramagnetic
Density 2.928 g/cm3
Melting point 194 °C (381 °F; 467 K)
Boiling point 268 °C (514 °F; 541 K)
hydrolyzes
Solubility soluble in dry
organic solvents
Structure
monoclinic
edge-shared bioctahedron
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 oxidizer, hydrolyzes to release HCl
Flash point Non-flammable
Related compounds
Other anions
Other cations
Related molybdenum chlorides
  • Molybdenum(IV) 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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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.

Structure

Usually called molybdenum pentachloride, it is in fact partly a

dimers partially dissociate to give a monomeric MoCl5.[4]
The monomer is paramagnetic, with one unpaired electron per Mo center, reflecting the fact that the formal oxidation state is +5, leaving one valence electron on the metal center.

Preparation and properties

MoCl5 is prepared by chlorination of Mo metal but also chlorination of MoO3. The unstable hexachloride MoCl6 is not produced in this way.[5]

MoCl5 is reduced by acetonitrile to afford an orange

acetonitrile complex, MoCl4(CH3CN)2. This complex in turn reacts with THF to give MoCl4(THF)2, a precursor to other molybdenum-containing complexes.[6]

Molybdenum(IV) bromide is prepared by treatment of MoCl5 with hydrogen bromide:

2 MoCl5 + 10 HBr → 2 MoBr4 + 10 HCl + Br2

The reaction proceeds via the unstable molybdenum(V) bromide, which releases bromine at room temperature.[7]

MoCl5 is a good

Lewis acid toward non-oxidizable ligands. It forms an adduct with chloride to form [MoCl6]−. In organic synthesis, the compound finds occasional use in chlorinations, deoxygenation, and oxidative coupling reactions.[8]

Reactions

MoCl5 is reduced by acetonitrile:[9]

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

Although it polymerizes tetrahydrofuran, MoCl5 is stable in diethyl ether. Reduction of such solutions with tin gives MoCl4((CH3CH2)2O)2 and MoCl3((CH3CH2)2O)3, depending on conditions.[10]

Safety considerations

MoCl5 is an aggressive oxidant and readily hydrolyzes to release HCl.

See also

References

  1. ISBN 0-12-352651-5
    .
  2. S2CID 95489209
    .
  3. ^ Wells, A. E. (1984). Structural Inorganic Chemistry (5th ed.). Oxford: Clarendon Press.
  4. doi:10.3891/acta.chem.scand.38a-0115
    .
  5. PMID 23172658
    .
  6. ISBN 9780470132593
    .
  7. doi:10.1039/DT9930000655
    .
  8. ISBN 9780471936237
    .
  9. ISBN 9780470132593
    .
  10. ISBN 9781118744994
    .
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