1,6,7,10-Tetramethylfluoranthene: Synthesis and Structure of a Twisted Polynuclear Aromatic Hydrocarbon

Article abstract of DOI:10.1016/S0040-4039(00)60565-8

The structure and synthesis of the overcrowded polynuclear aromatic 1,6,7,10-tetramethylfluoranthene, 1, is presented.The structures of 1 and 11 have been determined by X-ray diffraction to be twisted into conformations of approximately C₂ symmetry due to the buttressing of the flanking methyl groups.Semi-empirical calculations (AM1) on 1 find two minima, twist and fold; the twist is of lower energy.The energy for enantiomerization of 1 is set at below 7.0 kcal/mol by variable temperature NMR.Computations predict a likely path to account for the ribbon twist.