metal_sdf/MG_ideal.sdf

MG
  -OEChem-03222417103D

  1  0  0     0  0  0  0  0  0999 V2000
    0.0000    0.0000    0.0000 Mg  0  2  0  0  0  0  0  0  0  0  0  0
M  CHG  1   1   2
M  END
> <OPENEYE_ISO_SMILES>
[Mg+2]

> <OPENEYE_INCHI>
InChI=1S/Mg/q+2

> <OPENEYE_INCHIKEY>
JLVVSXFLKOJNIY-UHFFFAOYSA-N

> <FORMULA>
Mg+2

$$$$