Chemistry:Molybdenum(III) chloride

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Molybdenum(III) chloride
Molybdenum(III) chloride alpha polymorph
Molybdenum(III) chloride beta polymorph
IUPAC names
Molybdenum(III) chloride
Molybdenum trichloride
3D model (JSmol)
EC Number
  • 236-775-9
Molar mass 202.30 g/mol
Appearance dark red solid
Density 3.58 g/cm3
Melting point 410 °C (770 °F; 683 K) (decomposes)
Solubility insoluble in ethanol, diethyl ether
+43.0·10−6 cm3/mol
Flash point Non-flammable
Related compounds
Other anions
Molybdenum(III) fluoride
Molybdenum(III) bromide
Molybdenum(III) iodide
Other cations
Chromium(IV) chloride
Tungsten(V) chloride
Related molybdenum chlorides
Molybdenum(II) chloride
Molybdenum(IV) 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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Molybdenum(III) chloride is the inorganic compound with the formula MoCl3. It forms purple crystals.[1]

Synthesis and structure

Molybdenum(III) chloride is synthesized by the reduction of molybdenum(V) chloride with hydrogen.[2] A higher yield is produced by the reduction of pure molybdenum(V) chloride with anhydrous tin(II) chloride as the reducing agent.[3]

Molybdenum trichloride exists as two polymorphs: alpha (α) and beta (β). The alpha structure is similar to that of aluminum chloride (AlCl3). In this structure, molybdenum has octahedral coordination geometry and exhibits cubic close-packing in its crystalline structure. The beta structure, however, exhibits hexagonal close packing.[4]

THF complex

Molybdenum trichloride gives a THF complex MoCl3(thf)3. This pale orange solid is synthesized by reducing a THF solution of MoCl4(THF)2 with tin powder. The complex has octahedral geometry. The IR spectrum is free of intense bands in the 900–1000 cm−1, a characteristic of molybdenum oxo species.[5]

Hexa(tert-butoxy)dimolybdenum(III) is prepared by the salt metathesis reaction from MoCl3(thf)3:[6]

2 MoCl3(thf)3 + 6 LiOBu-t → Mo2(OBu-t)6 + 6 LiCl + 6 thf


  1. Perry, Dale L. (2011). Handbook of Inorganic Compounds (2nd ed.). Boca Raton: Taylor & Francis. pp. 279. ISBN 978-1-4398-1461-1. 
  2. "Preparation of Trichloride and Tetrachloride of Molybdenum". Journal of Research of the National Bureau of Standards Section A 63A (2): 185–188. 1959. doi:10.6028/jres.063A.013. PMID 31216151. 
  3. Larson, Melvin L. (1970). "Preparation of Some Metal Halides- Anhydrous Molybdenum Halides and Oxide Halides - A Summary". Inorganic Syntheses, Volume 12. pp. 178–181. 
  4. "Structural and scanning microscopy studies of layered compounds MCl3 (M= Mo, Ru, Cr) and MOCl2 (M= V, Nb, Mo, Ru, Os)". Journal of Alloys and Compounds 246 (1–2): 70–79. 1997. doi:10.1016/S0925-8388(96)02465-6. 
  5. Dilworth, Jonathan R.; Richards, Raymond L. (1990). "The Synthesis of Molybdenum and Tungsten Dinitrogen Complexes". Inorganic Syntheses 28: 33–43. doi:10.1002/9780470132593.ch7. 
  6. Broderick, Erin M.; Browne, Samuel C.; Johnson, Marc J. A. (2014). "Dimolybdenum and Ditungsten Hexa(Alkoxides)". Inorganic Syntheses 36: 95–102. doi:10.1002/9781118744994.ch18. 

Further reading

  • The Synthesis of Molybdenum and Tungsten Dinitrogen Complexes.. Inorganic Syntheses: Reagents for Transition Metal Complex and Organometallic Syntheses.. 28. January 1990. pp. 33–43.