䓬指环庚三烯正离子（tropylium ion），化学式 [C₇H₇]。

䓬正离子经常以m/z = 91的单峰出现在能裂解出苄基正离子（PhCH₂）的化合物的质谱图中，是后者的重排产物。比如甲苯的电子电离质谱图中的基峰就在 M-1 = 91，为亚稳的䓬正离子。

In organic chemistry, the tropylium ion is an aromatic species with a formula of [C₇H₇]. Its name derives from the molecule tropine (itself named for the molecule atropine). Salts of the tropylium cation can be stable, e.g., tropylium tetrafluoroborate. It can be made from cycloheptatriene (tropylidene) and bromine or phosphorus pentachloride.