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

Two novel compounds [(CH3)(4)N](3.5)H-1.5[PW11O39Ca(H2O)(2)]center dot 3H(2)O 1 and [(CH3)(4)N](3.5)H-1.5[PW11O39Sr(H2O)(2)]center dot 1.5H(2)O 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 W-O-t-M(M = Ca, Sr). The Ca(Sr) coordination cations occupy the vacant site of the [alpha-PW11O39](7-) subunit and are heptacoordinate with a distorted monocapped trigonal prismatic environment. (C) 2007 Elsevier B.V. All rights reserved.