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

Thierry Bataille (1) , A. Bouhali (2) , Cassendre Kouvatas (1, 3) , C. Trifa (2) , Nathalie Audebrand (1) , C. Boudaren (2)

1 ISCR - Institut des Sciences Chimiques de Rennes
2 UMC - Université frères Mentouri Constantine I
3 LCS - Laboratoire catalyse et spectrochimie

Considering the low dimensionality of the crystal structure of the known lead squarate tetrahydrate, Pb(C4O4)·4H2O, 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.

Keywords: thermal behaviour; phase transformation and polymorphism; in situ powder diffraction; lead squarate; solid state NMR

Domains: Chemical Sciences

Thierry Bataille, A. Bouhali, Cassendre Kouvatas, C. Trifa, Nathalie Audebrand, et al.. Hydrates and polymorphs of lead squarate Pb(C4O4): Structural transformations studied by in situ X-ray powder diffraction and solid state NMR. Polyhedron, 2019, 164, pp.123-131. ⟨10.1016/j.poly.2019.02.047⟩. ⟨hal-02090016⟩