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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.

Structure

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 know 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

  1. ^ Ulrich Müller (1981). "Hexameric Molybdenum Tetrachloride". Angewandte Chemie International Edition in English. 20 (8): 692. doi:10.1002/anie.198106921.
  2. ^ a b c McCann III, E. L.; Brown, T. M. (1970). "Molybdenum(IV) Chloride". Inorganic Syntheses. Inorganic Syntheses. Vol. 12. p. 181. doi:10.1002/9780470132432.ch31. ISBN 9780470132432.
  3. ^ Broderick, Erin M.; Browne, Samuel C.; Johnson, Marc J. A. (2014). "Dimolybdenum and Ditungsten Hexa(Alkoxides)". Inorganic Syntheses: Volume 36. Inorganic Syntheses. Vol. 36. pp. 95–102. doi:10.1002/9781118744994.ch18. ISBN 9781118744994.
  4. ^ Dilworth, Jonathan R.; Richards, Raymond L. (1990). "The Synthesis of Molybdenum and Tungsten Dinitrogen Complexes". Inorganic Syntheses. Inorganic Syntheses. Vol. 28. p. 33. doi:10.1002/9780470132593.ch7. ISBN 9780470132593.
  5. ^ Maria, Sébastien; Poli, Rinaldo (2014). "Ether Complexes of Molybdenum(III) and Molybdenum(IV) chlorides". Inorganic Syntheses: Volume 36. Inorganic Syntheses. Vol. 36. pp. 15–18. doi:10.1002/9781118744994.ch03. ISBN 9781118744994.
source: https://en.wikipedia.org/wiki/Molybdenum_tetrachloride