An alcohol-templated borate based on [Bi₁₄0₂₀(OH) ₆]^4- polyborate anions

A new borate [H₂EG][B₇O₁₀(OH)₃] (1) based on [B₁₄0₂₀(OH)₆]^4- polyborate anions has been solvothermally synthesized in the presence of H ₂EG as a template (EG = ethylene glycol). The structure was determined by single-crystal X-ray diffraction and further characterized by FTIR, elemental analysis and thermogravimetric analysis. Compound 1 crystallizes in the triclinic system, space group Pī, with a = 8.5095(4), b = 8.8694(4), c = 10.0756(4) Å, α = 95.094(2), β = 96.936(2), γ = 116.844(2)°, V = 664.66(5) ų. The structure of 1 consists of [B₁₄0₂₀(OH)₆]^4- moiety, which could be regarded as the largest isolated polyborate anion so far. The anions are interlinked via hydrogen bonding to form a 3D supramolecular network, whereas the diprotonated [H₂EG]²⁺are filled in the free space of inorganic borate network and interact with the inorganic framework by extensive hydrogen bonds. It is noteworthy that the EG acts not only as a solvent, but also as a template.