Preparation and Characteristic Properties of 1,4-Bis(3-guaiazulenylmethylium)benzene Bishexafluorophosphate

Reaction of guaiazulene (1) with a 0.5 molar amount of terephthalaldehyde in acetic acid in the presence of hydrochloric acid at 25 °C for 10 min under aerobic conditions selectively affords 1,4-bis(3-guaiazulenylmethylium)benzene dichloride (2), which upon treatment with hexafluorophosphoric acid quantitatively forms the title bishexafluorophosphate 3 as stable crystals.