The name/synonym for ligand MG (curated from ChEBI, PubChem, and PDB databases):

1MAGNESIUM(2+)
2MAGNESIUM, DOUBLY CHARGED POSITIVE ION
3MAGNESIUM(II) CATION
4MAGNESIUM, ION (MG(2+))
5MAGNESIUM(2+) ION
6MG2+
7MAGNESIUM CATION
8MG(2+)
9MAGNESIUM ION
10MG