Binuclear Silver(I) Pyrazolate Complexes with Pyrazolyl-pyridine Derivatives: Association via Intramolecular Hydrogen Bonds and Ag···Ag Contacts

Abstract

Cyclic trinuclear silver(I) complex, [AgPz]₃ (Pz = 3,5-bis(trifluoromethyl)pyrazolate), serves as a versatile platform for binding to chelating N^N-donor aromatic ligands. In this work, we have proposed derivatives of pyrazolyl-1H-pyridine (L) as ligands of this type, including 2-(3-phenyl-1H-pyrazol-5-yl)pyridine (L¹) and 2-methyl-6-(3-phenyl-1H-pyrazol-5-yl)pyridine (L²). It has been found that complex of the composition [AgPzL₁] (1 : 1 : 1) forms in solution regardless of reactants stoichiometry. The crystallization of the prepared compounds from toluene results in binuclear complexes with the composition [AgPz₂Ln]₂ per one solvent molecule. The formation of these compounds is caused by hydrogen bonding between the NH groups of pyrazolylpyridines (Lⁿ) and the unshared electron pair of the nitrogen atom of the pyrazolate ligand. Shortened Ag…Ag contacts (3.143–3.197 Å) have been observed in the complex, which leads to additional stabilization of the structure. The prepared compounds exhibit ligand-centered phosphorescence in solid state at ambient temperature.