A metal ion in a high-spin octahedral complex has two more unpaired electrons than the same ion does in a low-spin octahedral complex. Name some possible metal ions for which this would be true.

In octahedral complexes, the d-orbitals of a central metal ion are split into two energy levels due to the crystal field: three orbitals with lower energy known as t2g orbitals (dxy, dyz, and dxz), and two orbitals with higher energy level known as eg orbitals (dz^2 and dx^2-y^2). In a high-spin complex, the crystal field splitting energy (Δ_oct) is smaller compared to the pairing energy (the energy required to pair two electrons), and all electrons occupy the t2g orbitals before they start pairing in the eg orbitals. In a low-spin complex, the Δ_oct is greater than the pairing energy, and electrons will pair up in the t2g orbitals before moving to the eg orbitals.

To identify metal ions with the given condition, we need to look at the difference in the number of unpaired electrons between high-spin and low-spin complexes. Let's take the case of a common transition metal ion, Fe^3+, to illustrate. For Fe^3+, the electron configuration is [Ar]3d^5. In a high-spin octahedral complex, all five electrons would occupy the t2g orbitals without pairing, resulting in 5 unpaired electrons. Now let's consider a low-spin Fe^3+ octahedral complex. In this case, the electrons would prefer to pair up in the t2g orbitals due to the higher crystal field splitting energy. We would have two paired electrons in the t2g orbitals and one unpaired electron remaining, giving us a total of 3 unpaired electrons. The difference between the number of unpaired electrons in these two octahedral complexes is 5 - 3 = 2, which meets the given condition (two more unpaired electrons in a high-spin complex compared to a low-spin complex). Thus, Fe^3+ is a possible metal ion for which this condition holds true. Other possible metal ions for which this condition would be true include: 1. Co^2+ - High-spin: 4 unpaired electrons; Low-spin: 2 unpaired electrons 2. Ni^3+ - High-spin: 3 unpaired electrons; Low-spin: 1 unpaired electron