A pure inorganic 2-D framework based on paradodecatungstate and Mn2+ ions: syntheses, structure, and properties

Abstract

A pure inorganic 2-D framework based on paradodecatungstate polyanions and [Mn(H2O)n]2+ (n = 2, 3) ions, Na10{[Mn(H2O)3]2[H2W12O42]}{[Mn(H2O)3]2[Mn(H2O)4][H2W12O42]}·56H2O (1), has been synthesized and characterized by IR spectra, UV–vis spectra, thermogravimetric analysis (TGA), single-crystal X-ray diffraction, and magnetic measurements. Single-crystal X-ray diffraction analysis indicates that [H2W12O42]10− in 1 is a tetradentate ligand and coordinates to four [(Mn(H2O)3]2+ cations through terminal oxygens to form manganese doubly bridged 1-D chains, which are further linked through [Mn(H2O)4]2+ ions into a 2-D layer. The catalytic activities of 1 are tested in the selective oxidation of benzyl alcohol to benzaldehyde with 30% aqueous H2O2 as oxidant in toluene, exhibiting 90% conversion and 93% selectivity. Magnetic studies indicate that weak antiferromagnetic couplings exist between the Mn(II) ions in 1.