The manganate and permanganate ions are tetrahedral, due to:
1
The π-bonding involves overlap of p-orbitals of oxygen with d-orbitals of manganese
2
There is no π-bonding
3
The π-bonding involves overlap of p-orbitals of oxygen with p-orbitals of manganese
4
The π-bonding involves overlap of d-orbitals of oxygen with d-orbitals of manganese