In contrast to their acyclic analogues, 2-bromocyclohexa-1, 3-diene (11a) and 3-bromo-1, 5-dimethyl-cyclohexa-1, 3-diene (11b) do not react with silver ion, nor do they undergo solvolysis in 80% ethanol at temperatures up to 180°. The inertness to ionization of these cyclic bromodienes is attributed to steric inhibition of mesomerism involving the π electrons of the second double bond in the planar
与它们的无环类似物相反,2-
溴环己-1,3-二烯(11a)和3-溴-1,5-二甲基-环己-1,3-二烯(11b)不会与
银离子反应,它们也不会在温度高达180°的80%
乙醇中进行溶剂分解。这些环状
溴代二茂铁化合物电离的惰性归因于在平面
乙烯基阳离子12中涉及第二双键的π电子的介旋异构的空间抑制以及该假设中间体的弯曲结构。