3,14-Diethyl-2,13-diaza-6,17-diazoniatricyclo[16.4.0.07,12]docosane dichloride tetrahydrate from synchrotron radiation

The asymmetric unit of title hydrated salt, C22H46N4 2+·2Cl−·4H2O, comprises half a centrosymmetric dication, one Cl− anion and two water molecules of crystallization. The structure determination reveals that protonation has occurred at diagonally opposite amine N atoms, and that the dication features intramolecular N—H⋯N hydrogen bonds. In the crystal, a three-dimensional artchitecture is formed by O—H⋯Cl/N and N—H⋯Cl/O hydrogen bonds.

The asymmetric unit of title hydrated salt, C 22 H 46 N 4 2+ Á2Cl À Á-4H 2 O, comprises half a centrosymmetric dication, one Cl À anion and two water molecules of crystallization. The structure determination reveals that protonation has occurred at diagonally opposite amine N atoms, and that the dication features intramolecular N-HÁ Á ÁN hydrogen bonds. In the crystal, a three-dimensional artchitecture is formed by O-HÁ Á ÁCl/N and N-HÁ Á ÁCl/O hydrogen bonds.
The experiment at the PLS-II 2D-SMC beamline was supported in part by MEST and POSTECH. The coordination chemistry of tetraazamacrocycles with steric hindrance on the macrocyclic ring, and their complexes are of interest because of their various applications (Choi et al., 2010). Recently, the constrained cyclam derivatives have been reported to exhibit anti-HIV effects and to stimulate the activity of stem cells from the bone marrow (De Clercq, 2010).
The title compound, Fig. 1, containing a positively charged macrocycle, Cland water molecules was characterized during the studies of di-N-substituted macrocyclic ligands as well as their corresponding copper(II) complexes. The macrocylic ligand lies on a center-of-inversion. Thus, the asymmetric unit contains half of a macrocylic dication, one chloride anion and two water molecules. The four N atoms are coplanar, and the ethyl substituents are anti with respect to the macrocyclic plane as a result of the symmetry of the molecule. The C-C and C-N lengths and associated angles are in the normal range (Choi et al., 2006(Choi et al., , 2011. As expected, the N-C distances involving the protonated nitrogen atom, N1 are slightly longer than the other N-C distances. The cyclohexane ring that is fused to the 14-membered ring exists in a stable chair conformation, and the N1-C2-C3-N2 torsion angle displays a gauche conformation. The crystal structure is stabilized by different types of hydrogen bonds, Table 1.

Refinement
The C-bound H-atoms were placed in calculated positions (C-H = 0.98-1.00 Å) and were included in the refinement in the riding model approximation with U iso (H) set to 1.2-1.5U eq (C). The O-and N-bound H-atoms were located in a difference Fourier map and refined freely. One of the H atoms of the O2w water molecule was disordered over two sites of equal weight.

Figure 1
The molecular structure of title compound with displacements ellipsoids drawn at the 50% probability level for non-H atoms. Primed atoms are related by the symmetry operation 1/2-x, 1/2-y, 1-z.  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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (