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]

The structure of the hydrothermally synthesized barium lead borate contains an unusual fundamental building block, 2Δ4□:〈Δ2□〉–〈3□〉Δ, which was also found in the high-pressure form of CaB2O4 synthesized at 900 °C under a pressure of 15–25 kbar.