Benzamidinium tetrahydropentaborate sesquihydrate

Gustavo Portalone

doi:10.1107/s1600536808017522

Abstract

The asymmetric unit of the title compound [systematic name: benzamidinium 3,3′,5,5′-tetrahydroxy-1,1′-spirobi[2,4,6-trioxa-1,3,5-triboracyclohexane](1−) sesquihydrate], C7H9N2 +·B5H4O10 −·1.5H2O, is composed of two protonated benzamidinium cations, two tetrahydropentaborate anions and three water molecules of crystallization. The ions and water molecules are associated in the crystal structure by an extensive three-dimensional hydrogen-bonding network, which consists mainly of cation-to-anion N—H⋯O and anion-to-anion O—H⋯O hydrogen bonds.

Highlights

The asymmetric unit of the title compound [systematic name: benzamidinium 3,30,5,50 -tetrahydroxy-1,10 -spirobi[2,4,6-trioxa1,3,5-triboracyclohexane](1) sesquihydrate], C7H9N2+B5H4O101.5H2O, is composed of two protonated benzamidinium cations, two tetrahydropentaborate anions and three water molecules of crystallization
The ions and water molecules are associated in the crystal structure by an extensive three-dimensional hydrogen-bonding network, which consists mainly of cation-to-anion N—H O and anion-to-anion O—H O hydrogen bonds
Analysis of the crystal packing (Fig. 2) shows that adjacent [B5O6(OH)4]- units are hydrogen bonded to form eight-membered rings of graph set R22(8) (Etter et al, 1990; Bernstein et al, 1995; Motherwell et al, 1999). This anion-to-anion hydrogenbonding framework is supplemented by the formation of five hydrogen bonds from each benzamidinium cation to adjacent [B5O6(OH)4]- anions (Table 2)

Summary

Related literature

For crystal structure determinations of the tetrahydropentaborate anion, see: Loboda et al, (1993, 1994); Wiebcke et al. For hydration in molecular crystals, see: Gillon et al (2003). The asymmetric unit of the title compound [systematic name: benzamidinium 3,30 ,5,50 -tetrahydroxy-1,10 -spirobi[2,4,6-trioxa1,3,5-triboracyclohexane](1) sesquihydrate], C7H9N2+B5H4O101.5H2O, is composed of two protonated benzamidinium cations, two tetrahydropentaborate anions and three water molecules of crystallization. The ions and water molecules are associated in the crystal structure by an extensive three-dimensional hydrogen-bonding network, which consists mainly of cation-to-anion N—H O and anion-to-anion O—H O hydrogen bonds. Data collection: CrysAlis CCD (Oxford Diffraction 2006); cell refinement: CrysAlis RED(Oxford Diffraction 2006); data reduction: CrysAlis RED; program(s) used to solve structure: SIR97 (Altomare et al, 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999). Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: RZ2220)

Mo K radiation

Graphite monochromator

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