2-Methoxyethanaminium periodate 18-crown-6 clathrate

In the crystal structure of the title organic salt, C3H10NO+·IO4 −·C12H24O6, the protonated 2-methoxyethanaminium (CH3OC2H4—NH3 +) cation forms a 1:1 supramolecular rotator–stator complex with the 18-crown-6 molecule via N—H⋯O hydrogen bonds. The (CH3OC2H4—NH3 +) group is attached from the convex side of the bowl-shaped crown, in contrast to similar ammonium cations that nest in the curvature of the bowl. The cations are associated via N—H⋯O interactions, while the cations and anions are linked by weak C—H⋯O hydrogen bonds, forming cation–crown–anion chains parallel to [010].

In the crystal structure of the title organic salt, C 3 H 10 NO + Á-IO 4 À ÁC 12 H 24 O 6 , the protonated 2-methoxyethanaminium (CH 3 OC 2 H 4 -NH 3 + ) cation forms a 1:1 supramolecular rotator-stator complex with the 18-crown-6 molecule via N-HÁ Á ÁO hydrogen bonds. The (CH 3 OC 2 H 4 -NH 3 + ) group is attached from the convex side of the bowl-shaped crown, in contrast to similar ammonium cations that nest in the curvature of the bowl. The cations are associated via N-HÁ Á ÁO interactions, while the cations and anions are linked by weak C-HÁ Á ÁO hydrogen bonds, forming cation-crownanion chains parallel to [010].

Comment
The ability of 18-crown-6 ether (18-C-6) to form complexes with different metal ions and organic proton donors has been widely investigated. Because of their novel coordination modes, crown ethers have been widely used in catalysis, solvent extraction, isotope separation, bionics, materials chemistry, host-guest chemistry and supramolecular chemistry (Clark et al., 1998;Nakamura et al., 1998). Crown ethers recnetly have attracted much attention due to their ability to form non-covalent hydrogen-bonded complexes with ammonium cations, both in the solid state and in solution (Fender et al., 2002;Kryatova et al., 2004). The structures of organic ammonium RNH 3 + .crown ether assemblies in the solid state depend not only on the structure of the cation and the size of the crown ether ring, but also on the nature of the counter-anion. Various types of RNH 3 + structures (R =H, CH 3 , C 6 H 5 CH 2 , NH 2 , etc.) have been shown to form stable ammonium.crown ether complexes in the solid state (Akutagawa et al., 2005(Akutagawa et al., , 2009).
We report here the crystal structure of 2-methoxy-ethylamine periodate 18-crown-6 clathrate. X-ray crystallographic studies have been carried out for the complex C 3 H 9 NO +. IO 4 -.
C 12 H 24 O 6 at room temperature. An view of the complex is shown in Fig. 1. The ionic radius of NH 3 + matches the cavity size of six-O crown ethers, and N-H···O hydrogen bonds (Table 1)  Experimental 2-Methoxy-ethylamine (1.50 g, 0.02 mol), 18-crown-6 (5.28 g, 0.02 mol) and HIO 4 (4.56 g, 0.02 mol) were dissolved in 30 ml ethanol. Colorless s//ingle crystals of the title compound suitable for X-ray analysis were obtained via slow evaporation of the solvent at room temperature over a period of 3 days.

Refinement
Hydrogen atom positions were calculated and allowed to ride on their respective C atoms and N atoms with C-H distances of 0.93-0.97Å and N-H = 0.86 Å, and with U iso (H)=1.2U eq (C or N). Fig. 1. The molecular structure of the title compound, with the atomic numbering scheme (H atom labels have been omitted for clarity). Displacement ellipsoids are drawn at the 30% probability level, and N-H···O hydrogen bonds are shown as dotted lines. 2-Methoxyethanaminium periodate-18-crown-6 (1/1)

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.