Stable Oxoborate with Edge-Sharing BO4 Tetrahedra Synthesized under Ambient Pressure

摘要

Analysis of an atom's coordination and the linkage of polyhedra is of vital importance for understanding crystal structures, especially considering our general inability to forecast structure types for new systems of elements. As a general rule, the presence of shared edges or faces of polyhedra in a coordinated structure is common for large cations, but scarcely seen for high-valence low coordinated small cations. This conclusion is the main thrust of the Pauling's third and fourth rules and is especially strict for compounds such as borates, silicates, and phosphates. Until now, edge-sharing of those cation-oxygen (cation = B, Si, P) polyhedra was considered impossible except under extreme conditions.