Structural studies of some new lamellar magnesium, manganese and calcium phosphonates

Guang Cao, Haiwon Lee, Vincent M. Lynch, Thomas E. Mallouk

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Abstract

Layered phosphonate salts of divalent metal ions (Mg, Ca and Mn) are prepared by combining solutions of soluble metal salts and alkyl- or arylphosphonic acids. In this way the compounds Mg(O3PCnH2n+1)·H2O (n=1-12), Mg(O3PC6H5)·H2O, Mg(HO3PCH(C6H5)2) 2·8 H2O, Mn(O3PCH3)·H2O, Mn(O3PC6H5)·H2O, Ca(O3PCnH2n+1)·H2O (n≤5), Ca(HO3PC6H5)2 and Ca(HO3PCnH2n+1)2 (n≥6) were prepared. The M(O3PC6H5)·H2O compounds show good thermal stability, losing lattice water at 250-300°C without further decomposition below 550°C. Compounds derived from alkylphosphonic acids decompose at lower temperatures. The Mg(O3PCnH2n+1)·H2O series, Mg(O3PC6H5)·H2O, and Mn(O3PC6H5)·H2O group Pmn21; for the latter compound unit cell dimensions (Å) are a=5.733, b=14.298, c=4.931. The structure consists of roughly coplanar layers of metal atoms coordinated by phenylphosphonate groups above and below. Each metal atom is coordinated by five phosphonate oxygens and one lattice water molecule. Mg(O3PCnH2n+1·H2O adopts a similar structure; infrared spectra indicate all-trans alkyl chains. In Mg(HO3PCH(C6H5)2) 2·8 H2O, Mg(H2O) 2+6 ions and lattice water lie in hydrogen-bonded sheets; the benzhydryl groups lie above and below and make van-der-Waals contacts between layers.

Original languageEnglish (US)
Pages (from-to)63-69
Number of pages7
JournalSolid State Ionics
Volume26
Issue number2
DOIs
StatePublished - Jan 1 1988

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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