[2-(3,4-Dimethoxyphenyl)ethyl](3-{N-[2-(3,4-dimethoxyphenyl)ethyl]carbamoyl}propyl)azanium chloride dihydrate

The asymmetric unit of the title hydrated salt, C24H35N2O5 +·Cl−·2H2O, contains one organic cation that has its protonation site at the amine function, one chloride anion and two lattice water molecules. In the crystal, one pair of lattice water molecules and two chloride anions form a four-membered centrosymmetric hydrogen-bond cycle. In addition, O—H⋯O, N—H⋯O and N—H⋯Cl hydrogen bonds involving the N—H groups, the water molecules and the C=O group are observed. As a result, a hydrogen-bonded layer parallel to (100) is formed. The thickness of such a layer corresponds to the length of the a axis [21.977 (3) Å].


Crystal data
A perspective view of the moleculular entities of the title compound, showing the atomic numbering scheme, is given in Fig. 1. Bond lengths and angles are in normal ranges (Allen et al., 1987). The organic molecule contains two N atoms, amidic and aminic. The N atom on an amide is usually less nucleophilic than the N atom of an amine, due to the resonance stabilization of the N atom lone-pair provided by the amide carbonyl group. Therefore, in the cation the protonization of the amino N atom is observed.
In the crystal structure, two chloride anion and one lattice water molecule form a centrosymmetric four-membered hydrogen-bonding cycle (Fig. 2). The protonated organic molecules are bridged by N-H···Cl and C═O···H-O(w) hydrogen bonds (Table 1). As a result, hydrogen-bonded layers parallel to (100) are formed that have a thickness corresponding to the length of the a axis.

Experimental
To a solution of 2.0 g. (0.004 mol) N, N-(3,4-dimethoxyphenyl ethyl)succindiamide in 30 ml absolute benzene was added 6.7 g (0.04 mol) POCl 3 . The reaction mixture was boiled for 2 h. Benzene and excess POCl 3 were then removed under reduced pressure, and the residue was dissolved in 30 ml methanol. To the received solution was added 3.8 g (0.1 mol) NaBH 4 at 273-278 K under ice cooling. Then methanol was removed, the residue dissolved in water and extracted with chloroform. From the chloroformic layer were obtained three componds with R f 0.9, 0.5 and 0.2 (title compound) (chloroform:methanol=8:1). The compounds were isolated by column chromatography (silica gel); 0.075 g of the title compound were obtained with a m.p. 406-408 K. IR (KBr, ν, cm -1 ): 3434, 3258, 2940, 1651, 1590, 1519. Crystals suitable for X-ray diffraction analysis were obtained from a chloroform-methanol (8:1) mixture by slow evaporation.

Refinement
Carbon-bound H atoms were placed geometrically and treated as riding on their parent atoms, with C-H distances of

Figure 1
The molecular entities of the title compound with displacement ellipsoids drawn at the 50% probability level.  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.