Binuclear silver(I) pyrazolate complexes with pyrazolylpyridine derivatives: association via intramolecular hydrogen bonds and Ag⋯Ag contacts

Cyclic trinuclear silver(I) complex, [AgPz] (Pz = 3,5-bis(trifluoromethyl)pyrazolate), serves as a versatile platform for interaction with N^N-donor chelating aromatic ligands. In this study, pyrazolyl-1H-pyridine derivatives were proposed as ligands of this type, including 2-(3-phenyl-1H-pyrazole-5-yl)pyridine (L1) and 2-methyl-6-(3-phenyl-1H-pyrazole-5-yl)pyridine (L2). It was found that a complexes of the composition [AgPzL] (1 : 1 : 1), regardless of the stoichiometry of the reactants, form in solution. When the resulting compounds are crystallized from toluene, binuclear complexes with the composition [AgPzL] per one solvent molecule are formed. The formation of these structures is attributed to the formation of hydrogen bonds between the NH groups of pyrazole-pyridine (L) and the unshared electron pairs of the nitrogen atoms of the pyrazolate ligands. Shortened Ag...Ag contacts (3.143-3.197 Å) are observed in the complex, leading to additional stabilization of the structure. As a result, the compounds exhibit ligand-centered phosphorescence in the solid state at room temperature.