Two novel 1D linear chain alkaline-earth phosphotungstates: Synthesis and crystal structures of M/[α-PW11O39] (M = Ca, Sr)

Two novel compounds [(CH3)4N]3.5H1.5[PW11O39Ca(H2O)2]·3H2O 1 and [(CH3)4N]3.5H1.5[PW11O39Sr(H2O)2]·1.5H2O 2 based on lacunary Keggin-type phosphotungstate, have been synthesized by moderate temperature reaction in water and characterized by IR, TG, UV spectra, and X-ray single-crystal diffraction. X-ray single-crystal structural analysis reveals that the adjacent polyanions are polymerized to form a 1D infinitely linear chains by the bridging WOtM(M = Ca, Sr). The Ca(Sr) coordination cations occupy the vacant site of the [α-PW11O39]7− subunit and are heptacoordinate with a distorted monocapped trigonal prismatic environment.