# electron counting for transition metal-oxo ligand compound

Using donor-pair method, how many electrons would an oxo ($O^{2-}$) ligand contribute? I cannot decide if it is 2 or 4.

Ok

So a very large ligand like ETDA are hexadentate

But

I thought of different metals

Different metals can accept different amount of pairs in 1 oxo ligands

For example MnO4- Yes, it can hold total of 7pairs, and accept 4 electrons per oxo.

And then for W Tungsten is very large, and can therefore accept a lot of electrons from one O2-, in fact, it can handle 3 pairs, or 6 electrons