Guanidinium chloride–18-crown-6 (2/1)

In the crystal of the title compound, 2CH6N3 +·2Cl−·C12H24O6, the 18-crown-6 molecule is located across an inversion center. The guanidinium cation links to the 18-crown-6 molecule and chloride anion via N—H⋯O and N—H⋯Cl hydrogen bonds.

In the crystal of the title compound, 2CH 6 N 3 + Á2Cl À ÁC 12 H 24 O 6 , the 18-crown-6 molecule is located across an inversion center. The guanidinium cation links to the 18-crown-6 molecule and chloride anion via N-HÁ Á ÁO and N-HÁ Á ÁCl hydrogen bonds.
At home temperature (25°C), the single-crystal X-ray diffraction reveals that the structure get crystallization in the monoclinic system, space group P 21/n and the asymmetric unit of the title compound consists of a guanidinium cation, a chloride anion and a 18-crown-6 molecule ( Fig. 1). The three -NH 2 + groups form guanidinium interact with a O atoms of one crown ether molecule and Cl anions through two N-H···O an two N-H···Cl hydraogen bonds (Table 1), composing a tree-dimensional crystal structure (Fig. 2).

Experimental
The hydrochloric acid (0.36 g, 10 mmol) and guanidinium carbonate (0.9 g, 5 mmol) were dissolved in 30 ml water, and the solution was combined with methanol solution of 18-crown-6 (10 mmol). The mixture solution was stirred for 30 min to reaction fully. Blocky single crystals were obtained by slow evaporation of the filtrate after two weeks (yield 63%).

Refinement
H atoms were placed in geometrically idealized positions with C-H = 0.97 and N-H = 0.86 Å, and refined in riding mode with U iso (H) = 1.2U iso (N,C).

Computing details
Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure:   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