A series of three discrete dichloride dihydrates [Cl2(H2O)2]2− have been isolated with different triaminocyclopropenium (TAC) cations and with different crystallographic symmetries. The cluster exhibits D2h symmetry with the tris(dimethylamino)cyclopropenium cation [C3(NMe2)3]+, C2h symmetry with the fluorinated cation [C3(N(CH2CF3)2)(NBu2)2]+ (containing two 2,2,2‐trifluoroethyl substituents) and C2v symmetry with the more fluorinated [C3(N(CH2CF3)2)2(NBu2)]+ cation. The effect of symmetry on the infrared spectra of the dichloride ion‐pair clusters, as well as deuterated analogues, has been investigated. The D2h‐ and C2h‐symmetric clusters each exhibit two stretching bands in the infrared at 3427 and 3368 cm−1 for D2h symmetry and 3444 and 3392 cm−1 for C2h symmetry, whereas the C2v‐symmetric cluster exhibits three bands at 3475, 3426 and 3373 cm−1. Computational studies were carried out on a [Cl2(H2O)2]2− cluster with C2v symmetry to aid the infrared band assignments.

A discrete dichloride tetrahydrate cluster, [Cl 2 (H 2 O) 4 ] 2À , was obtained as a salt of the bis(diphenylamino)diethylamino cyclopropenium cation [C 3 (NPh 2 ) 2 (NEt 2 )] + and characterized by single-crystal X-ray diffraction and infrared spectroscopy. This chloride-chloride ion-pair cluster consists of a [Cl 2 (H 2 O) 2 ] 2À square with opposite edges bridged by water molecules to give a chair-like structure of the non-hydrogen atoms. The solid-state structure is essentially the same as the calculated gasphase structure. Infrared spectra were also collected on the deuterium analogue [Cl 2 (D 2 O) 4 ] 2À . Computational studies were carried out on gas-phase [Cl 2 (H 2 O) 4 ] 2À to confirm the infrared band assignments in the solid state. The structure and infrared spectrum are consistent with the discrete nature of the cluster.[a] M.