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

Abstract

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.