Two cadmium coordination polymers with bridging acetate and phenylenediamine ligands that exhibit two-dimensional layered structures

Two cadmium coordination polymers have two-dimensional polymeric structures in which monomeric units are joined by bridging acetate and benzenediamine ligands. Each of the CdII ions has an O4N2 coordination environment.

The N 2 O 4 coordination geometry of (II) can be described as severely distorted trigonal antiprismatic with bidentate acetate oxygen atoms and a 2 N:N 0 benzene-1,3-diamine nitrogen atom (O1O2N2 i ) forming one of the trigonal faces and two 2 O:O 0 acetate ligand oxygen atoms and a nitrogen atom from a 2 N:N 0 benzene-1,3-diamine (O3O4 ii N1) forming the other trigonal face (see Fig. 2). The atom-labeling scheme is shown in Fig. 3. The twist angles are 53.71 (11), 22.56 (8) and 45.38 (13) [average = 41 (16) ]. As seen in Table 2, the Cd-O bond lengths associated with the bidentate acetate ligand are shorter than those of the bridging, monodentate acetate ligands, as has been observed in other cadmium complexes (Wang et al., 2011.

Supramolecular features
As seen in Fig. 4, the supramolecular architecture of (I) exhibits independent layers in the bc plane, which are repeated in the [100] direction. Extensive N-HÁ Á ÁO hydrogenbonding interactions exist (see Table 3), but none of them extend between the layers. Based on an analysis of the extended structure using the SOLV routine of PLATON (Spek, 2009), the unit cell contains no solvent-accessible voids.
Compound (II) also exhibits a two-dimensional extended structure. Layers parallel to the bc plane and repeated in the [100] direction are observed as seen in Fig. 5. N-HÁ Á ÁO(acetate) hydrogen bonds (Table 4) are present within the layers. The water of hydration sits on a crystallographically imposed twofold rotation axis and, as seen in Fig. 6, is involved in O-HÁ Á ÁO and N-HÁ Á ÁO hydrogen-bonding interactions ( Table 4) that link adjacent layers. Packing diagram for (I) showing the two-dimensional network parallel to (100). All H atoms have been omitted for clarity.

Figure 2
Representations of the Cd II coordination environments observed in (I) and (II). Symmetry identifiers are those used in Figs. 1 and 3.

Figure 6
Partial packing diagram for (II) showing the hydrogen-bonded network.
Only H atoms involved in the hydrogen-bonded network are shown.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 5. For both (I) and (II), all hydrogen atoms were located in difference Fourier maps. The hydrogen atoms were refined using a riding model with a C-H distance of 0.98 Å for the methyl groups and 0.95 Å for the phenyl carbon atoms. The methyl hydrogen atom isotropic displacement parameters were set using the approximation U iso (H) = 1.5U eq (C). All other C-H hydrogen atom isotropic displacement parameters were set using the approximation U iso (H) = 1.2U eq (C). The N-H bond lengths were restrained to 0.88 Å in (I) and (II). The O-H bond length of the water of hydration in (II) was restrained to 0.84 Å and the H-O-H angle was restrained to 105 . U iso (H) was refined freely for the amine and water hydrogen atoms, except that for (II) the isotropic displacement parameters of the hydrogen atoms associated with N2 were restrained to be the same.  For both compounds, data collection: APEX2 (Bruker, 2013); cell refinement: APEX2 (Bruker, 2013); data reduction: SAINT (Bruker, 2013); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: PLATON (Spek, 2009) and Mercury (Macrae et al., 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

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.

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