*3.1. Synthesis*

The reaction of CuCl2·2H2O, 4-Ph-pzH, NaOH and PPNCl in 6:9:13:1 ratio and approximately 5 mL of various solvents yielded the trinuclear complex, PPN[Cu3(μ3-OH)(μ-4-Ph-pz)3Cl3] [33]. Compound (**1**) was prepared from the same reagents employing a 6:6:13:1 reagen<sup>t</sup> ratio in a more dilute reaction mixture (15 mL MeCN). Pettinari et al. have obtained a similar heptanuclear complex, [{Cu3(μ3-OH)(μ-pz)3(Cl)2(Hpz)2(H2O)}2{CuCl2(Hpz)2}], by acid digestion of the trinuclear [Cu3(μ3-OH)(μ-pz)3(CH3COO)2(pzH)] complex [34].

The azide complex (**2**) was synthesized in a metathesis reaction from (PPN)2[Cu3(μ3- Cl)2(μ-pz)3Cl3] by exchanging the terminal chlorides for azide using a slight excess of NaN3 dissolved in MeOH.

### *3.2. Crystal Structure Description of [PPN]2[{Cu3(*μ*3-OH)(*μ*-4-Ph-pz)3Cl3}2{Cu(4-Ph-pzH)4}]Cl2 (***1***)*

Complex (**1**) crystallizes in the triclinic space group *P*1 with the asymmetric unit containing one complete trinuclear and one-half of the mononuclear complex. Its crystal structure (Figure 1) is formed by repeating heptanuclear assemblies consisting of two trinuclear [Cu3(μ3-OH)(μ-4-Ph-pz)3Cl3] − anionic metallacycles on either side of a neutral, mononuclear, square planar [Cu(4-Ph-pzH)4]; the latter is located on the crystallographic inversion center. In the solid state, two Cl ions act as bridges between the central mononuclear complex and the two trinuclear ones [Cl(4)-Cu(1), 2.744(2) Å; Cl(4)-Cu(4), 2.792(2) Å], occupying axial sites and forming a weakly bonded heptanuclear assembly. The two trinuclear anions contain 4-coordinate distorted square planar Cu-centers and a pyramidal μ3-OH (the O atom is 0.473(4) Å away from the Cu3-plane), have their Cu3-planes parallel to each other and are connected via two long Cu(2) ... Cl(1) contacts of 3.023(2) Å to the adjacent heptanuclear unit; the μ-Cl atoms occupy one equatorial and one axial position with a Cu(1)–Cl(2)–Cu(2) angle of 101.00(6)◦. The one-dimensional chains thereby generated run parallel to the crystallographic *a*-axis (Figure 2) separated by the PPN<sup>+</sup> counterions. The long Cu(4) ... Cl(4) distances of 2.792(2) Å between the mononuclear [Cu(4-Ph-pzH)4] 2+ unit and the μ-Cl atoms are considered as non-bonding here; however, even longer distances of 2.817–2.839 Å have been reported in the corresponding *trans*-[CuCl2(pz\*H)4] complexes (pz\*H = pzH [35], 3-*t*Bu-pzH [36] and 3-Ph-pzH [37]). A complete list of bond lengths and angles for (**1**) is provided as Supplementary Material, Table S2.

**Figure 1.** Crystal structure and partial atom labeling scheme of (**1**). Phenyl groups on the pyrazolate ligands, H atoms and PPN counterions are not shown for clarity. Selected interatomic distances (Å) and angles (◦): Cu···Cu, 3.243(1), 3.417(1), 3.451(2), 5.228(3); Cu-O, 1.990(2)–2.012(3); Cu-N, 1.948(4)–1.957(3); Cu-Cl (terminal), 2.251(2)–2.307(2); Cu-Cl (bridging), 2.744(2); ∠CuOCu, 108.5(1)–118.3(2); <sup>∠</sup>(μ3-O)CuCl(terminal), 162.6(1)–169.3(1); ∠NCuN, 160.4(1), 163.3(2) and 175.7(2); ∠Cl(1)Cu(1)Cl(4), 110.10(4). For the mononuclear center, Cu-N, 2.017(4) and 2.017(4) Å; Cu-Cl (bridging), 2.792(2) Å; ∠NCuN, 91.6(1) and 180.

**Figure 2.** Molecular structure of (**1**) viewed parallel to the crystallographic *c* axis showing its polymeric character. Hydrogen atoms have been omitted for clarity.

### *3.3. Crystal Structure Description of (PPN)[Cu3(*μ*3-OH)(*μ*-pz)3(*μ*,*<sup>κ</sup>*1,1-N3)2(N3)] (***2***)*

The complex crystallizes in the monoclinic *P*21/c space group with the whole molecule in the asymmetric unit. The structure consists of triangular <sup>μ</sup>3-OH-capped metallacyclic units (O atoms at 0.345(2) Å from the Cu3 plane, Figure 3) connected by end-on bridging azides, forming infinite chains along the crystallographic *b*-axis (Figure 4), separated by the PPN<sup>+</sup> counterions. One of the three Cu centers is in square planar, whereas the other two are in distorted square pyramidal geometry. One of the three azide ligands is in a terminal monodentate coordination mode with Cu-N = 1.974(7) Å, and the other two are unsymmetrically bridging, in an end-on (μ,<sup>κ</sup>1,1) fashion, between two Cu3 units with Cu(1)–N(13) = 1.980(5), Cu(2)-N(13) = 2.421(5) and Cu(2)-N(3) = 2.001(5) Å, Cu(1)-N(3) = 2.322(5) Å at each bridgehead N, respectively. The bridging azides occupy one equatorial (shorter Cu-N bond) and one axial (longer Cu-N bond) at either side. The corresponding Cu–Nazide–Cu angles are 105.9(2) and 115.0(2)◦, respectively, holding the Cu atoms at intermolecular distances of 3.386(1) Å and 3.470(1) Å. As expected, in the two tetragonal pyramidal Cu-centers, the axial Cu-N bonds are significantly longer than the equatorial ones. The azide ions are approximately linear with N–N–N angles of 176.7(7)◦ and 178.3(7)◦; contain unequal N–N bond lengths, longer at the end involving the donor atoms, N3–N4 = 1.191(7) Å and longer at the dangling end, N4–N5 = 1.144(7) Å [38]. A complete list of bond lengths and angles for (**2**) is provided as Supplementary Material, Table S3.

**Figure 3.** Asymmetric unit of (**2**) (**left**). Inter-Cu3 contacts (**right**). H atoms, disordered azide ligand and PPN counterion are not shown for clarity. Selected interatomic distances (Å) and angles (◦): Cu···Cu, 3.386(1), 3.389(1), 3.470(1); Cu–O, 1.976(4), 2.000(4), 2.023(4); Cu-Npz, 1.935(5)–1.974(5); Cu-Nazide, 1.974(6), 1.980(5), 2.001(5); ∠CuOCu, 115.8(2), 116.8(2), 119.1(2).

**Figure 4.** Packing diagram of compound (**2**) shown along the crystallographic *b*-axis.
