Abstract: A new tetradecaborate, [H₃N(CH₂)₂NH₃]₂[B₁₄O₂₀(OH)₆](1), was synthesized by a boric acid ‘flux’ method, and characterized by X-ray powder diffraction, ICP, IR, TGA and DTA analyses. Single-crystal X-ray diffraction analysis showed that it crystallized in the monoclinic space group P1(No.2) with a=0.85092(10) nm, b=0.88678(11) nm, c=1.00724(13) nm, α=95.099(2)°, β=96.950(2)°, γ=116.845(2)°, V=0.66425(14) nm³, Z=2, R₁=0.0625[I>2σ(I)], and wR₂=0.1172(all data). The molecule structure of compound 1 comprises the isolated polyanion clusters [B₁₄O₂₀(OH)₆]^4– and diprotonated ethylenediamine molecules. Each polyanion cluster contains an 8-ring enclosed by six B₃O₃ 3-ring units. Adjacent clusters are further connected with each other through strong hydrogen-bonding interactions of N(O)―H···O to form a three dimensional(3D) supramolecular structure with 2D pseudo channels along the [010] and [001] directions. The diprotonated ethylenediamine molecules located in the channels interact with the host through extensive hydrogen-bonds. Compound 1 presents few example containing isolated polyborate anions synthesized by a boric acid ‘flux’ method.

Key words: Polyborate anion, Crystal structure, Boric acid “flux&rdquo, method