Potassium octachlorodimolybdate

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Potassium octachlorodimolybdate
Properties
Molecular formula Cl8K4Mo2
Appearance Red crystals
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Potassium octachlorodimolybdate is the inorganic compound with the formula K4Mo2Cl8. This red-coloured salt consists of potassium cations and the octachlorodimolybdate anion, Mo2Cl84-. The anion is of historic interest because it was one of the earliest illustrations of a quadruple bonding. The salt is usually obtained as the dihydrate.


The compound is prepared in two steps from molybdenum carbonyl:[1][2]

2 Mo(CO)6 + 4 HO2CCH3 → Mo2(O2CCH3)4 + 2 H2 + 12 CO
Mo2(O2CCH3)4 + 4 HCl + 4 KCl → K4Mo2Cl8 + 4 HO2CCH3
The octachlorodimolybdate(II) anion, [Mo2Cl8]4−, which features a quadruple Mo-Mo bond
The octachlorodimolybdate(II) anion, [Mo2Cl8]4−, which features a quadruple Mo-Mo bond

The reaction of the acetate with HCl was first described as providing trimolybdenum compounds,[3] but subsequent crystallographic analysis confirmed that the product contains the Mo2Cl84- ion with D4h symmetry. The Mo---Mo distance is 2.14 Å.[4]

[edit] References

  1. ^ A. B. Brignole, F. A. Cotton, Z. Dori, "Rhenium and Molybdenum Compounds Containing Quadruple Bonds" Inorganic Syntheses, 1972 Volume 13, pp. 81-89. doi:10.1002/9780470132449
  2. ^ Girolami, G. S.; Rauchfuss, T. B. and Angelici, R. J. (1999). Synthesis and Technique in Inorganic Chemistry. Mill Valley, CA: University Science Books. ISBN 0935702482. 
  3. ^ G.B. Allison, I.R. Anderson, and J.C. Sheldon "The Preparation of Halogenotrimolybdate(II) Compounds" Australian Journal of Chemistry 1967, Volume 20, pp. 869-876. doi:10.1071/CH9670869
  4. ^ Jurij V. Brencic and F. Albert Cotton "Octachlorodimolybdate(II) Ion. Species with a Quadruple Metal-Metal Bond" Inorganic Chemistry 1969, volume 8, pp 7-10 doi:10.1021/ic50071a002.
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