Dipolar Quinoidal Acene Analogues as Stable Isoelectronic Structures of Pentacene and Nonacene.
Quinoidal thia-acene analogues, as the respective isoelectronic structures of pentacene and nonacene, were synthesized and an unusual 1,2-sulfur migration was observed during the Friedel-Crafts alkylation reaction. The analogues display a closed-shell quinoidal structure in the ground state with a distinctive dipolar character. In contrast to their acene isoelectronic structures, both compounds are stable because of the existence of more aromatic sextet rings, a dipolar character, and kinetic blocking. They exhibit unique packing in single crystals resulting from balanced dipole-dipole and [C-H⋅⋅⋅π]/[C-H⋅⋅⋅S] interactions.
['Shi|Xueliang|X|', 'Kueh|Weixiang|W|', 'Zheng|Bin|B|', 'Huang|Kuo-Wei|KW|', 'Chi|Chunyan|C|']
aromaticity X-ray diffraction density functional calculations polycyclic aromatic hydrocarbons structure determination