Corannules

Structural formula
General
Surname	Corannules
other names	[5] Circulen; Dibenzo [ ghi, mno ] fluoranthene;
Molecular formula	C 20 H 10
External identifiers / databases
PubChem	11831840
ChemSpider	10006487
Wikidata	Q417774
properties
Molar mass	250,30 g · mol -1
safety instructions
GHS hazard labeling ; no classification available
GHS hazard labeling ; no classification available
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Corannulene , also known as [5] -circulene and dibenzo [ ghi, mno ] fluoranthene , is the smallest known and successfully synthesized representative of the [ n ] -circulene . It was first prepared in 1966 by Barth and Lawton in a remarkable 16-step synthesis using classical methods.

structure

Corannulene consists of five fused benzene rings that form a central pentagon and can therefore be regarded as the smallest fragment of fullerene (C ₆₀ ), which still has its characteristic curvature. This structural property “forces” the molecule to make the best possible compromise between delocalization and tension . Before the structure was clearly confirmed by X-ray diffraction analysis, it was difficult to predict whether it was planar or domed. Hanson and Nordmann showed that corannulene a curved, cup-like structure with C _5v - symmetry (see point groups has).

Dome model of the cup-shaped arched corannulene

The molecule shows a rapid shell inversion, the energy barrier of which on corannulene derivatives was measured by NMR experiments (at −64 ° C) to be 42.7 kJ / mol (10.2 kcal / mol) (approx. 200,000 inversions per second). The standard enthalpy of formation Δ H _f⁰ is 463.7 kJ / mol and was determined by means of bomb calorimetry .

The shell depth, which is defined by the distance between the two levels (which are spanned by the central five-membered ring and the ten carbon atoms of the edge), is 87 pm .

Individual evidence

↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
^ WE Barth, RG Lawton: Dibenzo [ghi, mno] fluoranthene , in J. Am. Chem. Soc. 88. 1966, pp. 380-381; doi : 10.1021 / ja00954a049 .
^ WE Barth, RG Lawton: The Synthesis of Corannulene , in: J. Am. Chem. Soc. 93. 1971, pp. 1730-1745; doi : 10.1021 / ja00736a028 .

[NV-1] This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.

[2] WE Barth, RG Lawton: Dibenzo [ghi, mno] fluoranthene , in J. Am. Chem. Soc. 88. 1966, pp. 380-381; doi : 10.1021 / ja00954a049 .

[3] WE Barth, RG Lawton: The Synthesis of Corannulene , in: J. Am. Chem. Soc. 93. 1971, pp. 1730-1745; doi : 10.1021 / ja00736a028 .