Aqua{μ-1,4-bis[(1,4,7,10-tetraazacyclododecan-1-yl)methyl]benzene}(nitrato-κO)dicopper(II) tris(nitrate) trihydrate

The title dinuclear CuII complex, the two CuII molecules both have a five-coordinate square-pyramidal geometry, but the molecules in the axial positions are different: a water molecule and a nitrate ion. All nitrate ions, water molecules, and N—H groups are involved in an intermolecular hydrogen-bond network.

data reports ring (composed of N1, N2, N3, and N4) at the equatorial positions and by the nitrate ion at the axial position. Meanwhile, Cu2 is coordinated by another cyclen ring (composed of N5, N6, N7, and N8) bridged via p-xylene. Unlike Cu1, the axial position of the coordination polyhedron around Cu2 is occupied by a water molecule. The intramolecular CuÁ Á ÁCu distance is close to the maximum possible value allowed by the ligand because Cu1 and Cu2 are located on opposite sides of the planar xylene spacer. Therefore, the apex of the square pyramid with Cu1 at the center points in the direction opposite to that having Cu2 at the center. The distances between Cu1 and N range from 2.011 (5) to 2.065 (5) Å , while those of Cu2 range from 2.000 (5) to 2.044 (5) Å , which are well within the typical ranges for C-N coordination bonds with amines. Soibinet and co-workers reported that the chelating nature of cyclen rings to Cu II in perchlorate salts were similar to nitrate salts (Soibinet et al., 2003). However, Cu II is coordinated by water molecules at the axial positions in both cases.
The coordination geometry index was calculated to determine the deviation from ideal coordination polyhedra around the copper ions using the formula = ( À )/60 , where and are the largest and second-largest angles in the coordination center, respectively (Addison et al., 1984). An ideal square pyramid has a value of 0, while an ideal trigonal bipyramid has a value of 1. The bond angles and of the N-Cu II -N chelate are 148.5 (2) and 152.0 (2) , respectively, around Cu1 and 148.7 (2) and 153.9 (2) , respectively, around Cu2. Accordingly, the values for Cu1 and Cu2 were calculated as 0.058 and 0.087, respectively. Therefore, the coordination geometry around the central Cu II could be characterized as a marginally distorted square pyramid. The deviations from an ideal square-pyramidal geometry in certain complexes arise from the distortion of the cyclen ring (i.e., the 12-membered macrocycle). Cyclam (1,4,8,, a 14-membered macrocyclic polyamine, exhibits an ideal square-pyramidal environment with the transitionmetal ions located in the plane formed by the nitrogen atoms of the ring (Ichimaru et al., 2022). In the title complex, Cu1 and Cu2 are located at distances of 0.521 (3) and 0.501 (3) Å , respectively, above the basal plane formed by the four nitrogen atoms of the cyclen ring.
All of the non-coordinating nitrate ions, water molecules, and N-H groups are involved in an intermolecular hydrogenbond network (Fig. 2). The hydrogen bonds between the N-H groups, except N7-H7, and nitrate ions produce a hydrogen-bond network wherein water molecules of solvation fill the gaps between the nitrate ions. Numerical values of the hydrogen-bonding interactions are summarized in Table 1.

Figure 1
The molecular structure of the complex cation in the title compound with displacement ellipsoids drawn at the 30% probability level. C-bound H atoms, counter-anions and solvate molecules are omitted for clarity.
plots. The Hirshfeld surface mapped over d norm with a standard resolution is illustrated in Fig. 3 along with fingerprint plots, which indicate the most important intermolecular contacts to be OÁ Á ÁH/HÁ Á ÁO (50.1%) and HÁ Á ÁH (41.2%). The significant frequency of HÁ Á ÁH and OÁ Á ÁH/HÁ Á ÁO interactions implies that van der Waals interactions and hydrogen bonding are critical in the crystal packing (Hathwar et al., 2015) of the title complex (Fig. 4). We previously reported that p-xylyl doubly-bridged Zn II -cyclen, p-bis(Zn II -cyclen), forms a characteristic helix-like supramolecular structure (Ichimaru et al., 2023). However, the packing of the title complex reported herein exhibits no specific supramolecular structures.

Figure 4
Packing view of the nitrate salt of p-bis(Cu II -cyclen) represented with polyhedral structures around the Cu II atoms, with displacement ellipsoids drawn at the 30% probability level. Non-coordinating nitrate ions, solvate water molecules and C-bound H atoms are omitted for clarity.   where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 1.08 e Å −3 Δρ min = −0.53 e Å −3 Absolute structure: Refined as an inversion twin Absolute structure parameter: 0.36 (5) data-2 IUCrData (2023). 8, x230462 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. Refined as a 2-component inversion twin. All hydrogen atoms were located by a geometrical calculation, and were not refined.