Molybdenum tetrachloride
IUPAC name	Molybdenum tetrachloride
Other names	Molybdenum(IV) chloride
Properties
Molecular formula	Cl4Mo
Appearance	black solid
Melting point	552°C
Solubility in water	Decomposes
Hazards
NFPA 704	0 3 1
Flash point	Non flammable
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Molybdenum tetrachloride is the inorganic compound with the empirical formula MoCl₄. The material exists as two polymorphs, a polymeric ("α") and a hexameric ("β") structures, 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]

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

2 MoCl₅ + C₂Cl₄ → 2 MoCl₄ + C₂Cl₆

The acetonitrile 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

[edit] References

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 "Molybpenum(IV) Chloride" Inorganic Syntheses 1970, volume 12, pages 181-186. doi:10.1002/9780470132432.ch31
3. ^ Jonathan R. Dilworth, Raymond L. Richards "The Synthesis of Molybdenum and Tungsten Dinitrogen Complexes" Inorganic Syntheses 1990, volume 28, pages 33-43. doi: 10.1002/9780470132593

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