3D-transition metal mono-substituted Keggin polyoxotungstate with an antenna molecule: synthesis, structure and characterization

Abstract

Three new organic–inorganic hybrid complexes based on 3d-transition metal monosubstituted Keggin polyoxometalates (POMs) with imidazole (Im) as pendant ligands, formulated as (HIm)₆[SiW₁₁O₃₉NiIm]_0.8[SiW₁₁O₃₉Ni(H₂O)]_0.2·7H₂O (1), (Im)₄Na₆[SiW₁₁O₃₉MnIm]_0.69[SiW₁₁O₃₉Mn(H₂O)]_0.31·7.5H₂O (2) and (HIm)₆[SiW₁₁O₃₉CoIm]_0.63[SiW₁₁O₃₉Co(H₂O)]_0.37·7H₂O (3), have been synthesized and characterized by IR spectroscopy, UV-visible spectroscopy, elemental analysis, TG analysis, cyclic voltammetry, magnetic properties, EPR and single-crystal/powder X-ray diffraction. The structural analyses indicate that the 3d metal atoms are incorporated into the vacancy of the α-[SiW₁₁O₃₉]⁸⁻ (SiW₁₁). Complexes 1–3 are the first examples of crystallographically characterized 3d-transition metal mono-substituted POMs with an antenna organic ligand synthesized under normal bench conditions.