Syntheses and crystal structures of two new pentaborates

Two new pentaborates, [Zn(DIEN)2][B5O6(OH)4]2 (DIEN=diethylenetriamine) (I) and [B5O7(OH)3Zn(TREN)] (TREN=tris(2-aminoethyl)amine) (II), have been hydrothermally synthesized and characterized by single crystal X-ray diffraction, FTIR, elemental analysis and thermogravimetric analysis. Compound I crystallizes in the monoclinic system, space group P21/c (No. 14), image, image, image, image°, image, image. The structure consists of isolated borate polyanion [B5O6(OH)4]− and zinc complex cation [Zn(DIEN)2]2+. The anionic units, [B5O6(OH)4]−, are linked by hydrogen bonds to form a 3D supramolecular network containing large channels, in which the templating [Zn(DIEN)2]2+ cation are located. II is monoclinic, P21/c (No. 14), image, image, image, image°, image, image. The structure of II is constructed from two distinct motifs, a usual [B5O7(OH)3]2− cluster and a supporting zinc complex [Zn(TREN)]2+, which are integrated through Zn–O–B linkage. This compound represents the first example of the combination of B–O cluster with transition-metal complex.