Diethyl 6,13-dioxo-5,7,12,13b,13c,14-hexahydro-6H,13H-5a,6a,12a,13a-tetraazabenz[5,6]azuleno[2,1,8-ija]benz[f]azulene-13b,13c-dicarboxylate 1,2-dichloroethane solvate

In the title inclusion compound, C26H26N4O6·C2H4Cl2, the solvent molecule occupies a cavity inside the clip-type molecule which is based on the glycoluril skeleton with two ethyl acetate substituents on the convex face of the glycoluril system. The dihedral angle between the aromatic rings of the host is 43.59 (4)° and the centroid–centroid distance is 6.741 (5) Å. The 1,2-dichloroetane molecule adopts a gauche conformation enabling it to participate in C—H⋯π interactions with the host. The packing motif in the title compound differs from that observed in the crystal structures of the host and in the benzene solvate. The host molecules are linked into tapes by π–π stacking interactions (centroid–centroid distance = 3.733 Å) and are further assembled into layers via C—H⋯O interactions. One of the ethyl groups is disorded over two positions with site-occupancy factors of 0.702 (14) and 0.298 (14).

In the title inclusion compound, C 26 H 26 N 4 O 6 ÁC 2 H 4 Cl 2 , the solvent molecule occupies a cavity inside the clip-type molecule which is based on the glycoluril skeleton with two ethyl acetate substituents on the convex face of the glycoluril system. The dihedral angle between the aromatic rings of the host is 43.59 (4) and the centroid-centroid distance is 6.741 (5) Å . The 1,2-dichloroetane molecule adopts a gauche conformation enabling it to participate in C-HÁ Á Á interactions with the host. The packing motif in the title compound differs from that observed in the crystal structures of the host and in the benzene solvate. The host molecules are linked into tapes bystacking interactions (centroid-centroid distance = 3.733 Å ) and are further assembled into layers via C-HÁ Á ÁO interactions. One of the ethyl groups is disorded over two positions with site-occupancy factors of 0.702 (14) and 0.298 (14).
In the triclinic pseudopolymorph, the asymmetric unit contains one host molecule and one solvent molecule of 1,2-dichloroethane ( Fig.1). There is a C-H···π interaction betweeen the host and the guest. The distance between atom H28B and Cg2 (the centroid of the C21-C26 ring) is 2.67 Å ( Table 1).
As solvent molecule occupies the cavity, the title compound exhibits different packing motif than the previously known two monoclinic forms. In Isaacs structure, the molecule was kined into three-dimensional network structure by π-π stacking, C-H···π and C-H···O hydrogen-bonds. In our previously reported structure of the apohost, the ethyl group occupied the cavity with C-H···π interactions and the molecules were linked into layers to the ab plane by four pairs of C-H···O hydrogen-bonds parallel .
The title molecules are linked into tapes by π-π stacking interactions. The benzene rings Cg1 (C1-C6) in the molecules at (x, y, z) and (1 -x, 1 -y, 1 -z) are strictly parallel, with an interplanar spacing of 3.589 Å, a ring centroid separation of 3.733 Å and a centroid offset of 1.027 Å. In addition, intermolecular C-H···O (Table 1) hydrogen-bonds link molecules into two-dimensional layer structure.

Experimental
The host compound was synthesized as reported previously (Wang et al., 2006). Crystals of the title compound were obtained by slow evaporation at 293 K of 1,2-dichoroethane/methanol (vol. 3:1) solution .

Refinement
The H atoms from methyl groups were placed in calculated positions, with C-H=0.96 Å, and refined to fit the electron density [U iso (H)=1.5U eq (C)]. Other H atoms were placed in calculated positions, with C-H = 0.93Å (aromatic) and 0.97Å supplementary materials sup-2 (methylene), and refined in riding mode [U iso (H)=1.2U eq (C)]. One of the ester ethyl groups (C13,C14) is disordered over two positions. Restraints were imposed on the geometry of the disordered ethyl group and anisotropic displacement parameters.

Fig. 2. Crystal packing of the title compound
Diethyl 6,13-dioxo-5,7,12,13b,13c,14-hexahydro-6H,13H-5a,6a,12a,13a-tetraazabenz [5,6]  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.

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