Ba6BO3Cl9 and Pb6BO4Cl7: structural insights into ortho-borates with uncondensed BO4 tetrahedra

Abstract

Two new halogen-rich ortho-borates, Ba₆BO₃Cl₉ and Pb₆BO₄Cl₇, were synthesized and characterized. Interestingly, Pb₆BO₄Cl₇ contains rare uncondensed BO₄ tetrahedra. The structure analyses indicate that the large cation/boron ratio, the stereochemically active lone pairs on Pb²⁺ cations and the rich Cl⁻ anions play key roles in the formation of the uncondensed BO₄ tetrahedra.