Now, in terms of the interactions in octahedral complexes, we're going to say that the strength of ligand orbital interactions depend on complex geometry and deorbital orientation. We're going to say here that for octahedral complexes, the ligands are on the axes. So remember we say on the axes or along the axes. They're both synonymous with one another, we're going to say on the axis.
Orbitals have the greatest interaction interactions with the ligands. So if we take a look here, what we have is a representation of our octahedral species. So think of it like 2 square pyramids that are stacked on top of each other or stacked inversely to each other. Their base is touching one another. So we have these six points which represents our ligands, and in the center we have our metal cation in theory.
Now on the axis, we say that the greatest interaction again happens on the X&Y axis. Here for this One South, it's dx2-y2. And then this one we have the most interactions happening on the Z axis, so dz2. In these two on the axis examples, we'd say that an increase in interaction causes an increase in energy.
Now in between the axes we have our other three orbitals. These don't line up in the correct orientation to have the greatest interaction. So we're going to say we have less interaction in this setup, which would cause a decrease in energy, or less energy involved. So just remember, when it comes to octahedral species themselves, the greatest interaction is happening on the axes or along the axes. So in particular we're talking about dx2-y2, and dz2. So just keep that in mind.