Conversely, ligands (like I and Br) which cause a small splitting Δ of the d -orbitals are referred to as weak-field ligands. In this case, it is easier to put electrons into the higher energy set of orbitals than it is to put two into the same low-energy orbital, because two electrons in the same orbital repel each other. So, one electron is put into each of the five d -orbitals in accord with Hund's rule, and "high spin" complexes are formed before any pairing occurs. For example, Br is a weak-field ligand and produces a small Δ oct. So, the ion [FeBr 6 ], again with five d -electrons, would have an octahedral splitting diagram where all five orbitals are singly occupied.