Application of the dimensional reduction formalism to PbBa[Li(PO)(PO)] (x = 0, 2, 6, 7): a series of phosphates with two types of isolated polyphosphate groups.

A series of phosphates, PbBa[Li(PO)(PO)] (x = 0, 2, 6, 7), have been synthesized by a high temperature solution method and the crystal structures were determined by single crystal X-ray diffraction. They are isostructural and crystallize in the triclinic space group P1[combining macron]. It is interesting that there are two kinds of isolated polyphosphate anionic groups coexisting in the crystal structure, which is rare among phosphates. Their structures exhibit zero-dimensional [Li(PO)(PO)] anionic clusters constructed by the LiO, PO and PO groups, which are separated by the Pb or Ba cations. The structure of Pb[Li(PO)(PO)] could be obtained using LiO as a dimensional reduction agent to dismantle PbPO. In addition, the infrared spectra and the UV-Vis-NIR diffuse reflectance spectra, as well as thermal analyses are reported. The first-principles theoretical studies are also carried out to understand the relationship between their electronic structures and linear optical properties.