Synthesis and Structural Characterization of Layered Calcium and Lanthanide Phosphonate Salts

Guang Cao, Vincent M. Lynch, J. Steven Swinnea, Thomas E. Mallouk

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Abstract

The crystal structures of two layered calcium phosphonate salts, Ca(O3PCH3)·H2O and Ca(HO3PC6H13)2, were solved by single-crystal X-ray diffraction. Ca(O3PCH3)·H2O is monoclinic, space group P21/c, with Z = 4, a = 8.8562 (13) Å, b = 6.6961 (10) Å, c = 8.1020 (10) Å, β; = 96.910 (11)°, and V = 476.97 (12) Å3. Ca atoms are coordinated by six oxygen atoms at a distance of ca. 2.4 Å, and by a seventh at 2.7 Å, making the coordination environment a distorted pentagonal bipyramid. In this salt, and in the structurally related M(O3PCnH2n+1)·H2O (n ≤ 5; M = Ca, Cd) series, the metal-phosphonate coordination is 5:5. Ca-(HO3PC6H13)2 is triclinic, space group P1, with Z = 2, a = 5.606 (2) Å, b = 7.343 (3) Å, c = 21.158 (7) Å, α = 97.31 (3)°, β = 96.98 (3)°, γ = 90.43 (4)°, and V = 857.2 (6) Å3. In this structure and the related Ca(HO3PCnH2+1)2 (6 < n < 18) series, the Ca atoms lie in approximately coplanar sheets and are coordinated by six oxygen atoms from different phosphonate groups lying above and below the plane. This structure is closely related to that of α-Zr(HPO4)2·H2O and the tetravalent metal phosphonates M(O3PR)2 (M = Zr, Hf, Ti, Ce). Layered trivalent metal phosphonate salts MH(O3PR)2 (R = alkyl, phenyl; M = La, Sm, Ce) were also prepared. LaH(Ò3PCH3)2 is triclinic with Z = 2, a = 5.398 (7) Å, b = 8.168 (18) Å, c = 10.162 (19) Å, α = 73.76 (16)°, β = 83.89 (13)°, γ = 73.50 (14)°, and V = 412.3 (13) Å3. The structure of the MH(O3PR)2 compounds appears to be closely related to that of the other 1:2 layered metal phosphonate salts Ca(HO3PCnH2n+1)2 and M(O3PR)2.

Original languageEnglish (US)
Pages (from-to)2112-2117
Number of pages6
JournalInorganic Chemistry
Volume29
Issue number11
DOIs
StatePublished - May 1 1990

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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