Table S1: Atomic number, ionic radius, electronegativity and ionization potential of the investigated bivalent metal iond.
| Metal ion | Mn2+ | Co2+ | Ni2+ | Cu2+ | Zn2+ |
| Atomic number | 25 | 27 | 28 | 29 | 30 |
| Ionic radius (Å) | 0.81 | 0.79 | 0.72 | 0.71 | 0.74 |
| Electronegativity (EN) | 1.55 | 1.88 | 1.91 | 2.00 | 1.65 |
| Second ionization potential (KJ.mol−1) | 1,509 | 1,648 | 1,753 | 1,958 | 1,733.3 |
| dValues from reference [31]. | |||||