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Question
Draw figure to show the splitting of d orbitals in an octahedral crystal field.
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Solution
- Let the six ligands be symmetrically located along the Cartesian axes and the metal atom is at the origin.
- On approaching the ligand, the energy of the d-orbitals increases as expected compared to the free ions. As is the case in a spherical crystal field.
- The orbitals along the axes (`d_(z^2)` and `d_(x^2 - y^2)`) repel more strongly than the dxy, dyz and dzx orbitals and have lobes directed between the axes.
- In the spherical crystal field, the `d_(Z^2)` and `d_(x^2 - y^2)` orbitals increase in energy and the dxy, dyz, dzx orbitals decrease in energy compared to the average energy.
d orbital splitting in an octahedral crystal field - Therefore, the degenerate set of d-orbitals splits into two groups: the low energy orbital group t2g and the high energy orbital group eg separated by energy Δo.
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