## 2 Results and Discussion
### Structural Aspects  
Recrystallization of **L**-**HCl** from an aqueous acetone solution leads to the formation of X-ray suitable crystals of **L**, which structure was initially solved and refined in the triclinic space group \(P\)1, and finally transformed to the monoclinic space group Cc. The molecular structure of **L** is shown in Figure 1. Table S1 in Supplementary Information contains the bond and angle values for **L**. The structure of **L** is stabilized by an intermolecular N-H\(\cdots\)N hydrogen bonds between the NH hydrogen atom of the formamidine fragment and the triazole nitrogen atom of a neighboring molecule (Table S2 in Supplementary Information). As a result, the formation of 1D polymeric chains is observed in the structure of **L**. Complexes **I**-**IV** were obtained as X-ray suitable blue crystals by slow evaporation of a solvent from their solutions. It should be noted that several crystals of each complex have been checked by a single crystal X-ray analysis, indicating their full identity. Both complexes **I** and **II** crystallize in the tetragonal space group \(I\)4\({}_{1}\)/a and are isomorphous. Therefore, only the crystal structure of complex **II** will be described. Complexes **III** and **IV** crystallize in the monoclinic space group \(P\)2\({}_{1}\)/a and triclinic space group _P_-1, respectively, and each exhibit 1D cationic Cu(II) containing polymeric chains. The molecular structures of **II** and **III** are shown in Figure 2.  
The discrete mononuclear complex **II** exhibits a distorted square pyramidal coordination polyhedron (Figure 2). In the basal plane, the Cu(II) atom is coordinated by four nitrogen atoms arising from four different NH\({}_{2}\)trz ligands, while the apical position is occupied by a water oxygen atom (Figure 2). The Cu(II) atom in **II** is almost in the basal plane of the square pyramid and only slightly deviated above the plane (0.1890(4) A). This is a surprising feature as in square pyramidal complexes the metal atom is usually located significantly above the basal plane [25]. This feature can be explained by the Cu\(\cdots\)F interaction between the metal center and one of the fluorine atoms of the PF\({}_{6}\) anion noted in **II**. Indeed, since the fluorine atom is located below the basal plane, it tends to drag the Cu(II) atom towards the bottom of the pyramid. The average Cu-N bond length is about 2.0 A  
Figure 1: Thermal ellipsoid (50%) plot of L along the _a_-axis. The nitrogen and carbon atoms are depicted in blue and grey, respectively. H-atoms were omitted for clarity. Figure 2: Thermal ellipsoid (50%) plot of **II** (**left**) and **III** (**right**). H-atoms and PF\({}_{6}\) anions in **II**, and non-coordinated Cl\({}^{-}\) anions and water molecules in **III** were omitted for clarity. The nitrogen atoms are depicted in blue, the carbon atoms in grey, the chloride ions in green and the copper atoms in red. (Table S3 in Supplementary Information). The Cu-O bond length is 2.263(3) A. The N-Cu-N bond angles formed by the nitrogen atoms, corresponding to the NH\({}_{2}\)trz ligands coordinated in a _cis_-arrangement are close to 90\({}^{\circ}\), while the N-Cu-N bond angles formed by the nitrogen atoms in _trans_-position are about 170\({}^{\circ}\) (Table S3 in Supplementary Information). The N-Cu-O bond angles are about 95\({}^{\circ}\) (Table S3 in Supplementary Information). Complexes **III** and **IV** each consist of 1D cationic Cu(II)-containing polymeric chains (Figures 2 and 3). The asymmetric unit of **IV** contains two non-equivalent Cu(II) atoms. Cu-Cu separations (\(\sim\)3.60-3.65 A) in both complexes exceed the sum of van der Waals radii of Cu(II) which indicates the absence of any distinct intramolecular Cu-Cu interactions. Each metal center in **III** and **IV** is coordinated by two chlorine atoms in _trans_-configuration and by four nitrogen atoms arising from four different NH\({}_{2}\)trz ligands (Figure 3). As a result, the formation of the distorted coordination octahedron is observed for both polymeric complexes.