2.1.1. Synthesis of [Ni(H2O)5(DMAP)](IPhth)·2H2O (1)

In 10 mL of de-ionized water, disodium salt of isophthalic acid (0.210 g, 1 mmol) was dissolved in a round-bottom flask. NiCl2·6H2O (0.237 g, 1 mmol) was then slowly added and mechanically stirred for an hour at room temperature. After an hour, *DMAP* (0.122 g, 1 mmol) was slowly added to the reaction mixture and the mixture was kept stirring for another two hours (Scheme 1). Then, the reaction mixture was kept in cooling conditions in a refrigerator (below 4 ◦C), which yielded pale blue block-shaped single crystals after a few days. Yield: 0.415 g (88.11%). Anal. calcd. for C15H28N2NiO11: C, 38.24%; H, 5.99%; N, 5.95%. Found: C, 38.13%; H, 5.92%; N, 5.87%. IR (KBr pellet, cm−1): 3454(br), 2817(w), 2729(w), 2124(br), 1620(s), 1586(sh), 1483(w), 1431(w), 1387(s), 1342(sh), 1224(w), 795(w), 730(w), 685(w) (s, strong; m, medium; w, weak; br, broad; sh, shoulder).

**Scheme 1.** Syntheses of the compounds **1** and **2**.

#### 2.1.2. Synthesis of [Co(Hdmpz)4(H2O)2]Cl2 (2)

CoCl2·6H2O (0.237 g, 1mmol) and *Hdmpz* (0.304 g, 4 mmol) were dissolved in de-ionized water (10 mL) in a round-bottom flask and the solution was allowed to stir mechanically for about two hours (Scheme 1). Then, the resulting solution was kept unperturbed in cooling conditions (24 ◦C), from which red block-shaped crystals were obtained after several days. Yield: 0.480 g (87.27%). Anal. calcd. for C20H36Cl2CoN8O2: C, 43.64%; H, 6.59%; N, 20.36%. Found: C, 43.55%; H, 6.51%; N, 20.27%. IR (KBr pellet, cm<sup>−</sup>1): 3457 (br), 3139 (sh), 3038 (w), 2980 (w), 2920 (m), 2869 (w), 2780 (w), 2714 (w), 2596 (m), 2463 (w), 2294 (m), 2139 (w), 1615 (s), 1571 (s), 1475 (s), 1418 (s), 1285 (s), 1247 (w), 1160 (s), 1040 (s), 988 (w), 782 (s), 701 (m), 612 (m), 517 (m) (s, strong; m, medium; w, weak; br, broad; sh, shoulder).

#### *2.2. Crystallographic Data Collection and Refinement*

Single crystals of the compounds **1** and **2** were selected, covered with Parabar 10320 (formally known as Paratone N) and mounted on a cryoloop on a BRUKER D8 Venture diffractometer, with a Photon III 14 detector, using an Incoatec high brilliance ImS DIA-MOND Cu tube (λ = 1.54178 Å) equipped with an Incoatec Helios MX multilayer optics. The crystals were kept at 151 K (compound **1**) or 100 K (compound **2**) during data collection. Data reduction and cell refinements were performed using the Bruker APEX4 program [28]. Scaling and absorption corrections were carried out using SADABS [29]. Crystal structures were solved by direct method and refined by full-matrix least-squares technique with SHELXL-2018/3 [30] using WinGX [31] platform. All the non-hydrogen atoms were refined anisotropically. The hydrogen atoms were placed at their calculated positions and refined in the isotropic approximation, except for those in compound 2 attached to water O-atoms, which were located using a Fourier difference map and refined isotropically.

Diamond 3.2 software was used to draw all the structural diagrams [32]. Table 1 contains the crystallographic data and the structure refinement table for the compounds.




**Table 1.** *Cont.*
