Tropylium tetrafluoroborate is an organic compound with the formula [C7H7]+[BF4]−.

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.

[1] This compound may be prepared by the reaction of cycloheptatriene with phosphorus pentachloride, followed by tetrafluoroboric acid.

[1][2]