. 2019 Sep 6;24(18):3247. doi: 10.3390/molecules24183247

Table 1.

Classification of the toxic metals, and the coordinating groups, according to their hard, intermediate (borderline), and soft character. The implied metal ions and coordinating groups are marked in red.

Metal Ions			Coordinating Groups
Hard	Borderline	Soft	Hard	Borderline	Soft
Li⁺, Na⁺, K⁺, Be²⁺ Mg²⁺, Ca²⁺, Sr²⁺, Mn²⁺, Al³⁺, Ga³⁺, Cr³⁺, Fe³⁺, Sn⁴⁺, (CH₃)₂Sn²⁺, UO₂²⁺, VO²⁺	Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Pb²⁺, Sn²⁺, Sb³⁺, Bi³⁺	Cu⁺, Ag⁺, Au⁺, Hg⁺, Pd²⁺, Cd²⁺, Pt²⁺, Hg²⁺, CH₃Hg⁺, Pt⁴⁺	H₂O, OH⁻, F⁻, RCOO⁻, Cl⁻, RO⁻, NH₃, RNH₂	C₆H₅NH₂	R₂S, RSH, RS⁻