Potassium octachlorodimolybdate

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Potassium octachlorodimolybdate(4−)
Identifiers
Properties
H4Cl8K4Mo2
Molar mass 631.9 g/mol
Appearance red crystals
Density 2.54 g/cm3
soluble
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

Potassium octachlorodimolybdate (systematically named potassium bis(tetrachloridomolybdate)(MoMo)(4−)) is an inorganic compound with the chemical formula K
4
Mo
2
Cl
8
(also written as K
4
[Cl
4
MoMoCl
4
]
). It is known as a red-coloured, microcrystalline solid. The anion is of historic interest as one of the earliest illustrations of a quadruple bonding. The salt is usually obtained as the pink-coloured dihydrate.

The octachlorodimolybdate(II) anion, [Mo2Cl8]4−, which features a quadruple Mo-Mo bond

The compound is prepared in two steps from molybdenum hexacarbonyl:[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 reaction of the acetate with HCl was first described as providing trimolybdenum compounds,[3] but subsequent crystallographic analysis confirmed that the product contains the Mo2Cl4–
8
ion with D4h symmetry. The Mo–Mo distance is 2.14 Å.[4]

References[edit]

  1. ^ Brignole, A. B.; Cotton, F. A.; Dori, Z. (1972). "Rhenium and Molybdenum Compounds Containing Quadruple Bonds". Inorg. Synth. Inorganic Syntheses. 13: 81–89. doi:10.1002/9780470132449.ch15. ISBN 978-0-470-13244-9. 
  2. ^ Girolami, G. S.; Rauchfuss, T. B.; Angelici, R. J. (1999). Synthesis and Technique in Inorganic Chemistry. Mill Valley, CA: University Science Books. ISBN 0-935702-48-2. 
  3. ^ Allison, G. B.; Anderson, I. R.; Sheldon, J. C. (1967). "The Preparation of Halogenotrimolybdate(II) Compounds". Aus. J. Chem. 20 (5): 869–876. doi:10.1071/CH9670869. 
  4. ^ Brencic, Jurij V.; Cotton, F. Albert (1969). ""Octachlorodimolybdate(II) Ion. Species with a Quadruple Metal–Metal Bond". Inorg. Chem. 8: 7–10. doi:10.1021/ic50071a002.