Dibenzohomopyracylene, a Segment of Methanofullerene C61H2, Its Radical Ions and Dianion

Abstract

Dibenzohomopyracylene (2), the 12b,12c-homo derivative of indeno[1,2,3-cd]fluoranthene (1), has been synthesized. Both 13

An Insight into the Aromaticity of Fullerene Anions: Experimental Evidence for Diamagnetic Ring Currents in the Five-Membered Rings of C606- and C706-

“…The nature of the skeleton of the bridged hexaanion, whether it is open or closed, is not obvious. The 1 J CH of 1 6 - , like those of 2 6- − 4 6- (Table ), has a value that is typical for an open bond. , On the other hand, the chemical shift of the carbon atom that is attached to the bridge appears at a higher field than that of the bridgehead carbon atoms in other “open” fullerenes (77.6 ppm), which might be taken as evidence against an open bond . It is perhaps relevant that changing the temperature , causes a slight change in the chemical shift of this peak (from 77.3 to 78.5 ppm for 165 and 298 K, respectively).…”

Spherical Aromaticity of Fullerenes

“…211 A similar deshielding of the 1 H resonance is found in dibenzohomopyracyclene 21, a closer structural model for 18. 212 This deshielding may to a large extent be due to a paratropic ring current along the pyracyclene perimeter with its 12 π electrons. 213,214 The fulleroid 19 is characterized by a large difference between the chemical shifts of the two inequivalent methylene protons, with ∆δ as large as 3.5 ppm.…”

4 Aromatic chemistry

“…Dibenzohomopyracylene 13cl (cl closed, op open) was synthesised by the route shown in Scheme 2. 2 This structure represents a segment of the 6^6-closed methanofullerene C 61 H 2 . Both 13 C NMR and X-ray diffraction data suggest that 13cl has a closed norcaradiene-like structure as opposed to the open structure 13op.…”

“…26 The ¢rst technique involved a [3,3]sigmatropic rearrangement to give enyne allene 135 followed by a Myers cyclisation. The second involved treatment of diyne substrate 138 with chlorodiphenylphosphine which effects a [2,3]sigmatropic rearrangement to give 139. Mild heating in cyclohexa-1,4-diene effects the Myers cyclisation.…”

“…Palladium catalysed arylation of compound 6 with phenylboronic acid followed by photochemical cyclisation gave polycyclic 9 which possesses a deep hydrophobic cavity.Dibenzohomopyracylene 13cl (cl closed, op open) was synthesised by the route shown in Scheme 2. 2 This structure represents a segment of the 6^6-closed methanofullerene C 61 H 2 . Both 13 C NMR and X-ray diffraction data suggest that 13cl has a closed norcaradiene-like structure as opposed to the open structure 13op.…”