2.2.3. Magnetic Measurements

The temperature dependence of the magnetization at an applied field of *B* = 1 T was acquired for powder samples of (**1**) and (**2**) using PPMS Dynacool magnetometer (Quantum Design Inc., San Diego, CA, USA). The experimental data were corrected for the underlying diamagnetism and signal of the sample holder. The experimental data were fitted with program Polymagnet [23].

### *2.3. Synthesis of Compounds (***1***) and (***2***)*

### 2.3.1. Synthesis of [PPN]2{[Cu3(μ3-OH)(μ-4-Ph-pz)3Cl3]2[Cu (4-Ph-pzH)4]}Cl2} (**1**)

CuCl2·2H2O (0.6 mmol, 102.3 mg), 4-Ph-pzH (0.8 mmol, 115.3 mg), NaOH (1 mmol, 40 mg) and PPNCl (0.1 mmol, 57.4 mg) were added to 15 mL CH3CN and the reaction mixture was stirred overnight. A small amount of a grey solid was filtered o ff and the solvent volume was reduced to 4 mL under reduced pressure. Suitable crystals for X-ray di ffraction were grown by slow evaporation. Yield: 45% (126 mg, 0.039 mmol). Crystal data for (**1**): Triclinic, *P*1, a = 14.161(7) Å, b = 17.814(8) Å, c = 18.173(9) Å, α = 80.66(1)◦, β = 68.33(1)◦, γ = 85.25(1)◦, V = 4202(4) Å3, Z = 1, R1 = 0.0661, GoF = 1.020, for 985 parameters and 17,116 observed reflections.

### 2.3.2. Synthesis of (PPN)[Cu3(μ3-OH)(μ-pz)3(<sup>μ</sup>1,1-N3)2(N3)] (**2**)

*Caution! Azide complexes of metal ions in the presence of organic ligands are potentially explosive. Only small amounts should be prepared, and they should be handled with care.*

A solution of NaN3 (0.375 mmol, 24.42 mg) in 5 mL of MeCN was added dropwise to a solution of [PPN]2 [Cu3(μ3-O)(μ-pz)3Cl3] (0.0628 mmol, 100 mg) suspended in 10 mL MeCN. The mixture was stirred overnight at rt. Well-shaped crystals suitable for X-ray di ffraction were obtained upon slow evaporation of the filtrate at room temperature over three weeks. The crystals were isolated, washed three times with methanol and ether and dried in the vacuum. Yield: 65% (44 mg, 0.041 mmol), based on Cu. Anal. calcd/found for C45 H40Cu3N16OP2:C, 50.36/50.01; H, 3.84/3.62; N, 20.89/20.48. Compound (**2**) was similarly synthesized in MeOH (instead of MeCN), albeit with a 40% yield. Crystal data for (**2**): monoclinic, *P21*/*<sup>c</sup>*, a = 8.6121(9) Å, b = 17.034(2) Å, c = 32.237(3) Å, β = 96.493(2)◦, V = 4698.8(8) Å3, Z = 4, R1 = 0.0662, GoF = 0.987, for 623 parameters and 5601 observed reflections.
