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].