Bis(7-methoxy-1-methyl-4,9-dihydro-3H-β-carbolinium) tetrachloridozincate

In the title compound, (C13H15N2O)2[ZnCl4], also known as di(harmalinium) tetrachloridozincate, the ZnII atom is in a distorted tetrahedral coordination of the chlorido ligands. In the cation, the methoxy and methyl groups are both coplanar with with rings to which they are attached [maximum deviations of 0.232 (4) and 0.259 (4) Å, respectively]. In the crystal, the alkaloid cations and metal complex anions interact by way of N—H⋯Cl hydrogen bonds involving each Cl atom, resulting in a network structure.

In the title compound, (C 13 H 15 N 2 O) 2 [ZnCl 4 ], also known as di(harmalinium) tetrachloridozincate, the Zn II atom is in a distorted tetrahedral coordination of the chlorido ligands. In the cation, the methoxy and methyl groups are both coplanar with with rings to which they are attached [maximum deviations of 0.232 (4) and 0.259 (4) Å , respectively]. In the crystal, the alkaloid cations and metal complex anions interact by way of N-HÁ Á ÁCl hydrogen bonds involving each Cl atom, resulting in a network structure.
The molecular structure is shown on Fig.1  Bond lengths and angles in the cations do not differ from their normal values. The alkaloid molecules are in a protonated form and the proton is localized at the nitrogen atom in the carboline ring as observed previously in structure of harmaline hydrochloride (Ferretti et al., 2004;Wouters, 1997). Protonization leads to a decrease in CH 2 -CH 2 and C═N bond lengths in comparison with the harmaline structure (Reimers et al., 1984). In the pyrrole cycle C-NH bond lengths are not equivalent as distinctions are expressed in a greater degree than for the harmaline crystal structure (Reimers et al., 1984). Both methoxy and methyl groups are located in the plane of the pyrrole and benzole rings and the carboline ring has a noncoplanar conformation with the torsion angles shown in the table 1. The sp 3 -hybridizied carbon atoms in the cycle being displaced from the mean plane of carboline cycle by -0.286 (4), -0.199 (4), 0.257 (5) and -0.090 (4) Å for C3, C4, C16, C17, respectively.
Unlike the parent harmaline structure (Reimers et al., 1984) in which only one hydrogen bond is present, in case of compound I a network of hydrogen bonds is formed (Fig.2) as in case of harmine hydrochloride where hydrogen bonds are formed between NH-groups as acceptors and chlorine atoms as donors of electrons (Ferretti et al., 2004;Wouters, 1997).

Experimental
The ZnCl 2 (1 mmol) and harmaline (2.5 mmol) were heated on water bath in 2M solution of hydrochloric acid in ethanol.
The resulting solution yielded colourless crystals which were filtered off and washed twice with acetone. Elem. Analysis found: C 49.0, H 4.7, N 8.8, Zn 10.3%; requires: C 49.0, H 4.7, N 8.8, Zn 10.3%. Crystals of the title compound, suitable to X-ray diffraction analysis, were selected directly from the sample as prepared.

Refinement
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 supplementary materials sup-2 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 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.   Bis(7-methoxy-1-methyl-4,9-dihydro-3H-β-carbolinium) tetrachloridozincate Crystal data (C 13

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 > σ(F 2 ) is used only for calculating Rfactors(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. supplementary materials sup-9