1,4,8,11-Tetraazoniacyclotetradecane tetrakis(hydrogensulfate)

In the title salt, C10H28N4 4+·4HSO4 −, the cation lies about an inversion center. In the crystal, O—H⋯O and N—H⋯O hydrogen bonds connect the anions and cations, forming a three-dimensional network.

In the title salt, C 10 H 28 N 4 4+ Á4HSO 4 À , the cation lies about an inversion center. In the crystal, O-HÁ Á ÁO and N-HÁ Á ÁO hydrogen bonds connect the anions and cations, forming a three-dimensional network.
Grateful thanks are expressed to Dr T. Roisnel (Centre de Diffractomé trie X, Université de Rennes 1) for the X-ray data collection. The chemistry of macrocyclic polyamine ligands with pendant arms has attracted much interest over the past two decades, because of their specific structures, chemical properties, their molecular recognition ability in the form of anions or cations, and their applications from radiopharmaceutical chemistry to waste-water treatment (Wainwright, 2001;Lukes et al., 2001;Zhang et al., 2003;Liu et al., 2004). Herein we report preparation and crystal structure of the title compound.

sup-1
The molecular structure of the title compound is shown in Fig. 1. The cation lies across a crystallographic inversion center and hence the asymmetric unit contains one half of the macrocyclic cation (cyclam) and two hydrogenosulfate anions. The tetra-protonated cyclam (C 10 H 28 N 4 ) 4+ cation exhibits C-C and C-N bond distances and angles in the range usually found for the cyclam molecule (Melson, 1979) and can be compared to related structures in the literature (Subramanian & Zaworotko, 1995;Ferchichi et al., 2010;Pojarová et al., 2010). In the crystal, O-H···O and N-H···O hydrogen bonds connect anions and cations to form a three-dimensional network (Fig. 2).

Experimental
The title compound was prepared by mixing zinc(II) sulfate heptahydrate (1 mmol; 0.287 g), 1,4,8,11-tetraazoniacyclotetradecane (2 mmol; 0.400 g) and 20 ml water. The resulting solution was acidified with 1 ml concentrated sulfuric acid (1 mmol) under continuous stirring. The title compound was obtained accidentally as we intended to make a zinc complex. In 3 days, white crystals were formed. The synthesis is reproducible and crystals obtained in this way are stable for a long time under normal conditions of temperature and humidity. Single crystals of the title compound were grown by slow evaporation from the aqueous solution at room temperature.

Refinement
H atoms bonded to C and N atoms were positioned geometrically and allowed to ride on their parent atom, with C-H = 0.97 Å, N-H = 0.90 Å and U iso = 1.2U eq (C, N). H atoms bonded to O atoms were included in their 'as found′ positions with refined isotropic displacement parameters.

Figure 2
Projection of part of the crystal structure of the title compound along the a axis, with hydrogen bonds indicated as dashed lines.

Special details
Experimental. Data were corrected for Lorentz-polarization effects and an analytical absorption correction (de Meulenaer & Tompa, 1965) was applied. The structure was solved in the P 1 21/c 1 space group by the direct methods (S and O) and subsequent difference Fourier syntheses (all other atoms), with an exception for H atoms bonded to C and N atoms which are positioned geometrically. Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.