Syntheses and crystal structures of two new pentaborates

Abstract

Two new pentaborates, [Zn(DIEN) 2][B 5O 6(OH) 4] 2 (DIEN=diethylenetriamine) ( I) and [B 5O 7(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 P2 1 /c (No. 14), a = 8.5686 ( 2 ) Å , b = 11.7883 ( 3 ) Å , c = 14.5407 ( 6 ) Å , β = 91.259 ( 2 ) °, V = 1468.39 ( 8 ) Å 3 , Z = 2 . The structure consists of isolated borate polyanion [B 5O 6(OH) 4] − and zinc complex cation [Zn(DIEN) 2] 2+. The anionic units, [B 5O 6(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, P2 1 /c (No. 14), a = 8.9969 ( 2 ) Å , b = 20.6903 ( 6 ) Å , c = 9.2878 ( 3 ) Å , β = 99.635 ( 2 ) °, V = 1704.52 ( 8 ) Å 3 , Z = 4 . The structure of II is constructed from two distinct motifs, a usual [B 5O 7(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.