Dipotassium cyclooctatetraenide explained

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.

Preparation and structure

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

2 K + C₈H₈ → K₂C₈H₈The 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. Book: A. L Wayda . Cyclooctatetraene Lanthanide Complexes. Lu(C₈H₈Cl(thf) and Lu(C₈H₈)[o-C₆H₄CH₂N(CH₃)₂(thf) | chapter = Cyclooctatetraene Lanthanide Complexes. Lu(C8 H8)Cl(THF) and Lu(C8 H8)[o -C6 H4 CH2 N(CH3)2 ](THF) | series = Inorganic Syntheses | date = 1990 | volume = 27 | pages = 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 . Dipotassium(I) cyclooctatetraenide-1-methoxy-2-(2-methoxyethoxy)ethane . Acta Crystallogr B . 30 . 1974 . 3 . 833–835 . 10.1107/S0567740874003840.