Abstract

Layered mixed divalent metal phosphonates Mg_1 − xZn_x(O₃PR)·H₂O [with R = CH₃, C₂H₃, C₆H₅] and Ni_1 − xZn_x(O₃PR)·H₂O [with R = CH₃, C₂H₃, C₆H₅, (CH₂)₂COOH] have been prepared by heating, respectively, mixed divalent magnesium–zinc hydroxides and nickel–zinc hydroxides above the melting point of the phosphonic acid being used. A range of pre-formed mixed divalent metal hydroxides Mg_1 − xZn_x(OH)₂ and Ni_1 − xZn_x(OH)₂ with different ratios of Zn content (x = 0, 0.1, 0.25, 0.5) are obtained by isomorphous substitution of zinc into the, respective, Mg(OH)₂ and Ni(OH)₂ brucite-type structure: space group Pm1; a = 3.13–3.15 Å, c = 4.63–4.77 Å). The phosphonate materials have been characterized by X-ray powder diffraction, IR, TGA, and ³¹P MAS NMR. Mg_1 − xZn_x(O₃PR)·H₂O and Ni_1 − xZn_x(O₃PR)·H₂O crystallize in an orthorhombic system with space group Pmn2₁ with b = 5.55–5.69 Å, c = 4.71–4.86 Å and a varying according to the size of the organic group R.