The cyclopentenium carbocation, cyclo-C₅H₇⁺ or CP⁺, and eight cyclic isomers were computationally investigated with quantum chemistry methods. These nine isomers display a significant structural diversity: three have a five-membered ring, four have a four-membered ring, and other two have a three-membered ring. The most stable isomer after CP⁺ is the dimethyl-cyclopropenium cation which is a \(2\pi\) aromatic molecule. The vibrational spectra of the nine cyclic isomers were simulated and the normal modes associated to the most intense peaks were identified. The charge distribution in the cyclic carbocations was explored with the quantum theory of atoms in molecules (QTAIM). It appears that the less stable isomers have in their rings either one carbon atom with a large negative charge or two/three linked carbon atoms with a small negative charge. Neutral derivatives of type CP-R (R = H, F, Cl, Br, I, and OH) were also investigated since they represent potential precursors in the large-scale generation of CP⁺. Among them, 3-iodo-cyclopentene is the precursor with the lowest bond dissociation enthalpy for the heterolytic rupture of the C–R bond.

利用量子化学方法对环戊烯碳正离子、环-C ₅ H ₇ ⁺或CP ⁺以及八种环状异构体进行了计算研究。这九种异构体显示出显着的结构多样性：三种具有五元环，四种具有四元环，另外两种具有三元环。^{CP +}之后最稳定的异构体是二甲基环丙烯正离子，它是\(2\pi\)芳香分子。模拟了九种环状异构体的振动光谱，并识别了与最强峰相关的简正模式。利用分子中原子量子理论（QTAIM）探索了环状碳正离子中的电荷分布。似乎不太稳定的异构体在其环中具有一个带大负电荷的碳原子或两个/三个带小负电荷的连接碳原子。还研究了 CP-R 型中性衍生物（R = H、F、Cl、Br、I 和 OH），因为它们代表了大规模生成 CP + 的潜在前^体。其中，3-碘环戊烯是C-R键异解断裂的键解离焓最低的前驱体。