K7{(BO3)Mn[B12O18(OH)6]} · H2O: first manganese borate based on covalently linked B12O18(OH)6 clusters and BO3 units via Mn2+ cations

A novel manganese oxyborate, K7{(BO3)[B12O18(OH)6]} · H2O (1), which is the first example showing the edge-sharing between boron and transition metal, has been solvothermally synthesized. The structure consists of [B12O20(OH)4] and [BO3] which are linked through unusual MnO5 polyhedron via vertexes and edges. This compound exhibits NLO properties and the intensity of the green light (frequency-doubled output: λ=532 nm) produced by 1 is as large as that of KDP.