Crystallographic and computational study of a network composed of [ZnCl4]2− anions and triply protonated 4′‐functionalized terpyridine cations

We report herein the synthesis, crystallographic analysis and a study of the noncovalent interactions observed in the new 4′‐substituted terpyridine‐based derivative bis[4′‐(isoquinolin‐2‐ium‐4‐yl)‐2,2′:6′,2′′‐terpyridine‐1,1′′‐diium] tris[tetrachloridozincate(II)] monohydrate, (C₂₄H₁₉N₄)₂[ZnCl₄]₃·H₂O or (ITPH₃)₂[ZnCl₄]₃·H₂O, where (ITPH₃)³⁺ is the triply protonated cation derived from 4′‐(isoquinolin‐4‐yl)‐2,2′:6′,2′′‐terpyridine (ITP) [Granifo et al. (2016). Acta Cryst. C 72 , 932–938]. The (ITPH₃)³⁺ cation presents a number of interesting similarities and differences compared with its neutral ITP relative, mainly in the role fulfilled in the packing arrangement by the profuse set of D —H…A [D (donor) = C, N or O; A (acceptor) = O or Cl], π–π and anion…π noncovalent interactions present. We discuss these interactions in two different complementary ways, viz. using a point‐to‐point approach in the light of Bader's theory of Atoms In Molecules (AIM), analyzing the individual significance of each interaction, and in a more `global' analysis, making use of the Hirshfeld surfaces and the associated enrichment ratio (ER) approach, evaluating the surprisingly large co‐operative effect of the superabundant weaker contacts.