Two novel metal borates with three-dimensional open-framework layers constructed from [M2B8O20(OH)2] (M = Al, Ga) cluster units

Abstract

Two novel metal borates, Ba[MB₄O₈(OH)]·H₂O (M = Al/Ga), with a three-dimensional open-framework layer have been synthesized under hydro(solvo)thermal conditions, in which the Al³⁺/Ga³⁺ ions have been successfully introduced into the oxoboron cluster backbone and further linked together to form the open-framework layer composed of the [M₂B₈O₂₀(OH)₂] cluster units. The half-unit [MB₄O₁₁(OH)] can be viewed as analogous to the known [B₅O₉(OH)] cluster. Interestingly, the rare M–O–M linkages play a crucial role in forming the open-framework layer.