# 10.4.3: Pi Donors in the Angular Overlap Model

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Ligands in which the donor atom has more than one lone pair are capable of pi donation to the metal. Common examples include halide and alkoxide ligands. The overlap question in this case is exactly the same as in the case of pi acceptors; the same table of interactions applies here. However, since the ligand electrons are forming the pi bond in this case, the ligand electrons are stabilized and the d orbitals with which they overlap are destabilized.

In octahedral geometry, for example, we see the off-axis d orbitals raised modestly in energy in the presence of pi donor ligands. The angular overlap model allows us to quantify the relative changes in energy because of these ligand interactions.

##### Example $$\PageIndex{1}$$

Confirm the stabilization and destabilization of orbitals due to pi donation in the octahedral interaction diagram shown above.

###### Solution

Positions 1, 2, 3, 4, 5, 6.

• dz2: 0
• dx2-y2: 0
• dxy: (0 + 1 + 1 + 1 + 1 + 0) = 4 eπ
• dxz: (1 + 1 + 0 + 1 + 0 + 1) = 4 eπ
• dyz: (1 + 0 + 1 + 0 + 1 + 1) = 4 eπ
• Ligand in position 1: (0 + 0 + 0 + 1 + 1) eπ = 2 eπ
• Ligand in position 2: (0 + 0 + 1 + 1 + 0) eπ = 2 eπ
• Ligand in position 3: (0 + 0 + 1 + 0 + 1) eπ = 2 eπ
• Ligand in position 4: (0 + 0 + 1 + 1 + 0) eπ = 2 eπ
• Ligand in position 5: (0 + 0 + 1 + 0 + 1) eπ = 2 eπ
• Ligand in position 6: (0 + 0 + 0 + 1 + 1) eπ = 2 eπ

This page titled 10.4.3: Pi Donors in the Angular Overlap Model is shared under a CC BY-NC 4.0 license and was authored, remixed, and/or curated by Chris Schaller.