High-temperature, high-pressure hydrothermal synthesis, crystal structure, and infrared and NMR spectroscopy of a barium lead borate with a 2D layer structure: [Ba₃Pb(H₂O)][B₁₁O₁₉(OH)₃]

With a high-temperature, high-pressure hydrothermal technique, a new barium lead borate, [Ba₃Pb(H₂O)][B₁₁O₁₉(OH)₃] (1), has been synthesized and characterized by single-crystal X-ray diffraction, and infrared and solid-state NMR spectroscopy. The structure of1contains planar thick layers of borates with the Ba²⁺cations at sites in the inter- and intralayer space. Each layer consists of three single sheets. The central sheet is very corrugated and is built up from the fundamental building block (FBB) . On both sides of the central sheet there are borate single chains formed of the very rare FBB viacorner-sharing. This FBB was first observed in a high-pressure polymorph of CaB₂O₄. These chains are linked into a sheet by PbO₅(H₂O) polyhedra, which are further linked to the central sheet by sharing vertices between triangles and tetrahedra to form a thick layer. The IR spectrum shows the presence of hydroxyl groups of HBO₄, water molecules, BO₃triangles, and BO₄tetrahedra. The presence of BO₃and BO₄polyhedra was also confirmed by¹¹B MAS NMR spectroscopy.