Substituent Effects on the Supramolecular Aggregation of Ag^I‑Pyrazolato Trimers

The interplay of argentophilic and dipolar (π-acid···base) interactions, on one hand, and the presence or absence of interstitial solvent molecules, on the other, determines the supramolecular organization of trinuclear silver-pyrazolato complexes in the solid state. The crystal structures of one gold and six silver metallacyclic complexes of the type [M^I(μ-pz*)]₃, where pz* are the substituted pyrazolato anions 3,5-Ph₂-pz, 3-Me-5-Ph-pz, 4-Br-3,5-Ph₂-pz, 4-Br-3-^tBu-pz and 3-(o-Cl-C₆H₄)-pz and M = Ag and Au, are discussed in the context of their supramolecular organization. Two silver complexes, for which the π-acid character of their Ag₃-faces is maximized by their peripheral electron-withdrawing substituents, show crystal packing dominated by short Ag₃···Br contacts, the first structural manifestation of supramolecular structure via dipolar interactions involving the tunable π-acidity of the Ag₃-face.