carbo-Naphthalene: A Polycyclic carbo-Benzenoid Fragment of α-Graphyne.
A ring carbo-mer of naphthalene, C32Ar8(Ar=p-n-pentylphenyl), has been obtained as a stable blue chromophore, after a 19-step synthetic route involving methods inspired from those used in the synthesis of carbo-benzenes, or specifically devised for the present target, like a double Sonogashira-type coupling reaction. The last step is a SnCl2/HCl-mediated reduction of a decaoxy-carbo-decalin, which is prepared through successive [8+10] macrocyclization steps. Two carbo-benzene references are also described, C18Ar6and o-C18Ar4(C≡C-SiiPr3)2. The carbo-naphthalene bicycle is locally aromatic according to structural and magnetic criteria, as revealed by strong diatropic ring current effects on the deshielding of1H nuclei of the Ar groups and on the negative value of the DFT-calculated NICS at the center of the C18rings (-12.8 ppm). The stability and aromaticity of this smallest fused molecular fragment of α-graphyne allows prediction of the same properties for the carbon allotrope itself.
CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, BP44099, 31077, Toulouse Cedex 4, France.|Université de Toulouse, UPS, ICT-FR 2599, 31062, Toulouse Cedex 9, France.
Kévin
K
Cocq
Université de Toulouse, UPS, Institut de Chimie de Toulouse ICT-FR-2599, 31062, Toulouse Cedex 9, France.
Nathalie
N
Saffon-Merceron
CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, BP44099, 31077, Toulouse Cedex 4, France.
Yannick
Y
Coppel
CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, BP44099, 31077, Toulouse Cedex 4, France.|Université de Toulouse, UPS, ICT-FR 2599, 31062, Toulouse Cedex 9, France.
Corentin
C
Poidevin
CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, BP44099, 31077, Toulouse Cedex 4, France.|Université de Toulouse, UPS, ICT-FR 2599, 31062, Toulouse Cedex 9, France.
Valérie
V
Maraval
CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, BP44099, 31077, Toulouse Cedex 4, France.|Université de Toulouse, UPS, ICT-FR 2599, 31062, Toulouse Cedex 9, France.
Remi
R
Chauvin
aromaticity; carbocycles; density functional calculations; macrocycles; structure elucidation