title: Tropylium tetrafluoroborate
text: # Tropylium tetrafluoroborate
  
  Tropylium tetrafluoroborate is an organic compound with the formula $[C_7H_7]^+[BF_4]^−.$ Containing the tropylium cation and the non-coordinating tetrafluoroborate counteranion, tropylium tetrafluoroborate is a rare example of a readily isolable carbocation. It is a white solid.
  
  This compound may be prepared by the reaction of cycloheptatriene with phosphorus pentachloride, followed by tetrafluoroboric acid.
  
  