The crystal structure and characteristic chemical property of 1,2-bis(3-guaiazulenylmethylium)benzene bishexafluorophosphate

Reaction of guaiazulene (1) with a 0.5 molar amount of phthalaldehyde in a mixed solvent of acetonitrile and diethyl ether in the presence of hexafluorophosphoric acid at 25°C under aerobic conditions rapidly gives the title dicarbocation compound, 1,2-bis(3-guaiazulenylmethylium)benzene bishexafluoro-phosphate (2) in 98% yield. Reduction of 2 with a large excess of NaBH4 in a mixed solvent of acetonitrile and ethanol at 25°C quantitatively affords a unique intra-molecular cycloaddition compound 9 via the intermediate 8. The crystal structure and characteristic chemical property of 2 are reported.