Luminescent silver nitrate complexes of bis[2-(diphenylphosphano)phenyl]ether (DPEphos): Crystal structure of [Ag(DPEphos)(py2SH)2]NO3

Heteroleptic silver(I) nitrate complexes containing the bis[2-(diphenylphosphano)phenyl]ether (DPEphos) ligand and the heterocyclic thioamides pyridine-2(1H)-thione (py2SH), pyrimidine-2(1H)-thione (pymtH), 4,6-dimethylpyrimidine-2(1H)-thione (dmpymtH), 1,4,5,6-tetrahydropyrimidine-2-thione (thpymtH) or 1,3-imidazolidine-2-thione (imtH2) have been synthesized and characterized by IR and UV–Vis spectroscopy, elemental analyses and melting point determinations. The complexes can be obtained by the addition of the thioamide ligand to an AgNO3–diphosphane adduct in dichloromethane/ethanol solution. The molecular structure of [Ag(DPEphos)(py2SH)2]NO3 complex has been established by single-crystal X-ray diffraction. The structure features a tetrahedral silver(I) center with two phosphorus atoms from the chelating diphos ligand, and the exocyclic sulfur atom of two heterocyclic thioamide units. Intense blue-green emission is observed in the region 470–483 nm for all the complexes in the solid state and in solution at ambient temperature.

Graphical abstractThe reaction between silver nitrate, bis[2-(diphenylphosphano)phenyl]ether (DPEphos), and a heterocyclic thione results in the formation of compounds of the formula [Ag(DPEphos)(thione)2]NO3. X-ray structural analysis of the pyridine-2-thione derivative reveals a slightly distorted tetrahedral geometry around the silver(I) metal center which is surrounded by the P atoms of the bidentate DPEphos and the two S-donor atoms of the py2SH ligands. Strong luminescence, with the excited-state responsible for the emission presumably having a metal perturbed IL character, is observed for all the complexes. In addition, there is strong evidence for the participation of S → Ag charge transfer in the emissive excited state.Figure optionsDownload full-size imageDownload as PowerPoint slide