Hydrates and polymorphs of lead squarate Pb(C4O4): Structural transformations studied by in situ X-ray powder diffraction and solid state NMR

摘要

Considering the low dimensionality of the crystal structure of the known lead squarate tetrahydrate, Pb (C4O4)center dot 4H(2)O, the thermal reactivity of the powdered compound and structural studies of lower hydrates have been investigated from X-ray single-crystal and powder diffraction data, solid state NMR and thermal analyses. It is shown that Pb(H2O)(C4O4) and two polymorphs of anhydrous PbC4O4 can be formed within different conditions. The departure of the water molecules leads to the condensation of initial inorganic chains into 2D or 3D-type crystal structures. The full decomposition of the squarate ligand provides successive lead oxides. (C) 2019 Elsevier Ltd. All rights reserved.