Triple-Vertex Linkage of (BO4)-Tetrahedra in a Borosulfate: Synthesis, Crystal Structure, and Quantum-Chemical Investigation of Sr[B3O(SO4)4(SO4H)]

Borosulfates are classified as silicate analogue materials. The number of crystallographically characterized compounds is still limited, whereas the structural diversity is already impressive. The anionic substructures of borosulfates exhibit vertex-connected (BO4)- and (SO4)-tetrahedra, whereas bridging between two (SO4)- or even between two (BO4)-tetrahedra is scarce. The herein presented compound Sr[B3O(SO4)(4)(SO4H)] is the first borosulfate with a triple-vertex linkage of three (BO4) tetrahedra via one common oxygen atom. DFT calculations complement the experimental studies. Bader charges (calculated for all atoms) as well as charge-density calculations give hint to the electron distribution within the anionic substructure and density-of-states calculations support the interpretation of the bonding situation.

Automated summary

Borosulfates, classified as silicate analogue materials, exhibit impressive structural diversity with limited crystallographic data. The compound Sr[B3O(SO4)(4)(SO4H)] is the first borosulfate identified with a triple-vertex linkage of three (BO4) tetrahedra. DFT calculations and experimental studies complement each other to provide insights into the electron distribution and bonding situation within the anionic substructure.