The name/synonym for ligand SO4 (curated from ChEBI, PubChem, and PDB databases):

1SULFATE
2[SO4](2-)
3TETRAOXIDOSULFATE(2-)
4SO4(2-)
5SULPHATE
6TETRAOXOSULFATE(VI)
7SULPHATE ION
8TETRAOXOSULFATE(2-)
9SULFATE ION