Unraveling the Decomposition Process of Lead(II) Acetate: Anhydrous Polymorphs, Hydrates, and Byproducts and Room Temperature Phosphorescence

Lead­(II) acetate [Pb­(Ac)2, where Ac = acetate group (CH3–COO–)2] is a very common salt with many and varied uses throughout
history. However, only lead­(II) acetate trihydrate [Pb­(Ac)2·3H2O] has been characterized to date. In this paper,
two enantiotropic polymorphs of the anhydrous salt, a novel hydrate
[lead­(II) acetate hemihydrate: Pb­(Ac)2·1/2H2O], and two decomposition products [corresponding
to two different basic lead­(II) acetates: Pb4O­(Ac)6 and Pb2O­(Ac)2] are reported, with their
structures being solved for the first time. The compounds present
a variety of molecular arrangements, being 2D or 1D coordination polymers.
A thorough thermal analysis, by differential scanning calorimetry
(DSC) and thermogravimetric analysis (TGA), was also carried out to
study the behavior and thermal data of the salt and its decomposition
process, in inert and oxygenated atmospheres, identifying the phases
and byproducts that appear. The complex thermal behavior of lead­(II)
acetate is now solved, finding the existence of another hydrate, two
anhydrous enantiotropic polymorphs, and some byproducts. Moreover,
some of them are phosphorescent at room temperature. The compounds
were studied by TGA, DSC, X-ray diffraction, and UV–vis spectroscopy.