The crystal structures of tris(ethylmethylamino)cyclopropenium bromide and tris(allylmethylamino)cyclopropenium chloride are found to contain weak dimers of the cyclopropenium cation whereas the structure of the mixed salt of tris(dimethylamino)cyclopropenium chloride and dimethylammonium chloride reveals half of the cyclopropenium cations to have formed dimers and the other not to have formed dimers. These structures are compared to three related triiodide salts ([C3(NMeEt)3]I3, [C3(NEt2)3]I3 and [C3(NBu2)3]I3) as well as the previously-reported salts [C3(NEtMe)3]Cl, [C3(NH2)3]Cl, [C3(NH2)3]I and [C3(NEt2)3]I. The distances between the C3 centroids of the staggered dimers are at the short end of those normally found in π-stacked neutral arenes, let alone charged aromatic rings. Factors leading to the formation of dimers and the effect of dimer formation on the cyclopropenium structures are investigated. The crystal structures of triaminocyclopropenium halide salts are shown to exhibit dimer formation in some cases, but not in others, whereas corresponding triiodide salts only form cationic monomers in the solid state.

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三氨基环丙烯鎓卤化物和三碘化物盐：环丙烯鎓二聚体的形成

发现三（乙基甲基氨基）溴化环丙烯鎓和三（烯丙基甲基氨基）氯化环丙烯鎓的晶体结构含有环丙烯鎓阳离子的弱二聚体，而三（二甲氨基）环丙烯氯化物和二甲基氯化铵的混合盐的结构揭示了环丙烯鎓阳离子的一半已经形成二聚体，另一个没有形成二聚体。将这些结构与三种相关的三碘化物盐（[C3(NMeEt)3]I3、[C3(NEt2)3]I3 和 [C3(NBu2)3]I3）以及先前报道的盐 [C3(NEtMe) 3]Cl、[C3(NH2)3]Cl、[C3(NH2)3]I 和 [C3(NEt2)3]I。交错二聚体的 C3 质心之间的距离处于通常在 π 堆叠中性芳烃中发现的那些的短端，更不用说带电的芳环了。研究了导致二聚体形成的因素以及二聚体形成对环丙烯鎓结构的影响。三氨基环丙烯鎓卤化物盐的晶体结构在某些情况下显示出二聚体形成，但在其他情况下不显示，而相应的三碘化物盐仅在固态下形成阳离子单体。