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 [MI(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.