Insights into the Topology and the Formation of a Genuine ppσ Bond: Experimental and Computed Electron Densities in Monoanionic Trichlorine [Cl(3)](−)

So far, several publications have discussed the bonding concepts in polyhalides on a theoretical basis. In particular, the trichlorine monoanion is of great interest because its structure should be symmetrical and show two equidistant Cl−Cl bonds. However, apart from matrix‐isolation studies, only asymmetric trichlorine anions have been reported so far. Herein, the trichlorine monoanions in 2‐chloroethyltrimethylammonium trichloride [NMe(3)EtCl][Cl(3)], 1, tetramethylammonium trichloride [NMe(4)][Cl(3)], 2, and tetrapropylammonium trichloride [NnPr(4)][Cl(3)], 3, are analysed. High‐resolution X‐ray structures and experimental charge density analyses supported by periodic quantum‐chemical calculations provide insight into the influence of the crystalline environment on the structure of these [Cl(3)](−) anions as well as into the progress of the bond formation between a dichlorine molecule and a Cl(−) anion.