Molybdenum tetrachloride

Molybdenum tetrachloride is the inorganic compound with the empirical formula MoCl4. The material exists as two polymorphs, a polymeric ("α") and a hexameric ("β") structure, although neither form is soluble in any solvent without degradation. In each polymorph, the Mo center is octahedral with two terminal chloride ligands and four doubly bridging ligands.[1]

Molybdenum tetrachloride
IUPAC name
Molybdenum tetrachloride
Other names
Molybdenum(IV) chloride
3D model (JSmol)
ECHA InfoCard 100.033.039 Edit this at Wikidata
Molar mass 237.752 g/mol
Appearance black solid
Melting point 552 °C (1,026 °F; 825 K)
NFPA 704 (fire diamond)
Flammability code 0: Will not burn. E.g. waterHealth code 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasReactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no codeNFPA 704 four-colored diamond
Flash point Non flammable
Related compounds
Related compounds
Molybdenum(II) chloride
Molybdenum(III) chloride
Molybdenum(V) 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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Infobox references

It can be prepared from by dechlorination of molybdenum pentachloride using tetrachloroethene:[2]

2 MoCl5 + C2Cl4 → 2 MoCl4 + C2Cl6

The acetonitrile complex adduct, which is a versatile intermediate, can be prepared directly from the pentachloride:[3]

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


  1. ^ Ulrich Müller "Hexameric Molybdenum Tetrachloride" Angewandte Chemie International Edition in English 1981, Volume 20, Pages 692 - 693. doi: 10.1002/anie.198106921
  2. ^ E. L. Mccann III, T. M. Brown "Molybdenum(IV) Chloride" Inorganic Syntheses 1970, volume 12, pages 181-186. doi:10.1002/9780470132432.ch31
  3. ^ Broderick, Erin M.; Browne, Samuel C.; Johnson, Marc J. A. (2014). "Dimolybdenum and Ditungsten Hexa(Alkoxides)". Inorganic Syntheses: Volume 36. Inorganic Syntheses. 36. pp. 95–102. doi:10.1002/9781118744994.ch18. ISBN 9781118744994.