Dipotassium cyclooctatetraenide

Dipotassium cyclooctatetraenide, sometimes abbreviated K2COT, is an organopotassium compound with the formula K2C8H8. It is a brown solid that is used as a precursor to cyclooctatetraenide complexes, such as uranocene (U(C8H8)2). Analogs of K2C8H8 are known with ring substituents, with different alkali metals, and with various complexants.

Ball-and-stick model of COT2−
Dipotassium cyclooctatetraenide
Names
Preferred IUPAC name
Dipotassium cycloocatetraenediide
Identifiers
3D model (JSmol)
ChemSpider
  • InChI=1S/C8H8.2K/c1-2-4-6-8-7-5-3-1;;/h1-8H;;/q-2;2*+1/b2-1-,5-3-,8-6-;;
    Key: JEUFATMWOKTCQC-YGFQESQOSA-N
  • InChI=1/C8H8.2K/c1-2-4-6-8-7-5-3-1;;/h1-8H;;/q-2;2*+1/b2-1-,5-3-,8-6-;;
    Key: JEUFATMWOKTCQC-YGFQESQOBL
  • [K+].c1=c[cH-]c=c[cH-]c=c1.[K+]
Properties
C8H8K2
Appearance beige solid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Preparation and structure

Potassium cyclooctatetraenide is formed by the reaction of cyclooctatetraene with potassium metal:

2 K + C8H8 → K2C8H8

The reaction entails 2-electron reduction of the polyene and is accompanied by a color change from colorless to brown.[1]

The structure of K2(diglyme)C8H8 has been characterized by X-ray crystallography of the derivatives with diglyme complexed to the potassium cations. The C8H8 unit is planar with an average C-C distance of 1.40 A.[2]

References
  1. A. L Wayda (1990). "Cyclooctatetraene Lanthanide Complexes. Lu(C8 H8 )Cl(THF) and Lu(C8 H8 )[o -C6 H4 CH2 N(CH3 )2 ](THF)". Cyclooctatetraene Lanthanide Complexes. Lu(C8H8Cl(thf) and Lu(C8H8)[o-C6H4CH2N(CH3)2(thf). Inorganic Syntheses. Vol. 27. pp. 150–154. doi:10.1002/9780470132586.ch28. ISBN 9780470132586.
  2. J. H. Noordik, T. E. M. van den Hark, J. J. Mooij and A. A. K. Klaassen (1974). "Dipotassium(I) cyclooctatetraenide-1-methoxy-2-(2-methoxyethoxy)ethane". Acta Crystallogr B. 30 (3): 833–835. doi:10.1107/S0567740874003840.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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