Synthesis, characterization and crystal structure of a Er III mono-substituted [α-SiW 11O 39] 8− polyoxotungstate containing one-dimensional zigzag chainlike structure

Abstract

A Keggin-type monovacant silicotungstate derivative K 2H 2{Er(H 2O) 6[Er(H 2O) 3SiW 11O 39]} 2·22H 2O ( 1) has been synthesized by reaction of the polyoxometalate α-K 8SiW 11O 39·13H 2O ligands with erbium III cations in the aqueous solution under moderate condition, and characterized by elemental analyses, IR, UV-visible spectroscopy and X-ray single-crystal diffraction. Crystal data: K 2H 2{Er(H 2O) 6[Er(H 2O) 3SiW 11O 39]} 2·22H 2O, triclinic, P−1, a=12.463(3), b=14.849(3), c=16.772(3) Å, α=95.37(3), β=94.65(3), γ=106.76°, Z=1, R 1=0.0638, wR 2=0.1140. X-ray single-crystal diffraction reveals that the polyanion of crystalline 1 is made up of two crystallographically identical polyoxometalate-based {Er(H 2O) 6[Er(H 2O) 3SiW 11O 39]} 2− building block units, which are linked through erbium centers by means of the terminal oxygen atoms from the backbone of precursor [α-SiW 11O 39] 8−, generating a novel 1D chain-like structure. Variable-temperature magnetic susceptibility study indicates the presence of the relatively strong spin-orbital coupling in compound 1 in the wide temperature region of 70–300 K.