Synthesis and characterization of silver(III) complexes with tetradentate and tridentate ligands with imine-oxime groups

The trivalent oxidation state of silver is stabilized by tetradentate imine-oxime and tridentate imine-oxime-amine ligands. Silver(I), in the presence of these ligands, is readily oxidized by PbO2 in acidic solutions or by S2O82- to the corresponding silver(III) complexes. The isolated complexes were characterized by elemental analysis, IR, UV–Vis spectra, magnetic susceptibility, TG and cyclic voltammetry. The complexes are diamagnetic, consistent with the formation of spin-paired d8 square planar or tetragonal structures. The complexes have a high molar absorption in the UV–Vis region with ε > 104 M−1 cm−1, that may be attributed to ligand to metal charge transfer (MLCT). The complexes seem to be stable in the solid state when kept dry and away from light. The complexes decompose very slowly in aqueous solutions. The rate of decomposition is accelerated by both acids and bases. The decomposition involves oxidation of the ligands by AgIII.

Graphical abstractSilver(I) in the presence of tetradentate and tridentate ligands having imine-oxime groups are readily oxidized to the corresponding silver(III) complexes. The isolated complexes are diamagnetic and their cyclic voltammograms are electrochemically irreversible. The complexes have high molar absorption in the visible region that may be attributed to ligand to metal charge transfer (LMCT).Figure optionsDownload full-size imageDownload as PowerPoint slide