Repulsion between metal d orbitals and ligand electrons in an octahedral complex leads to the removal of degeneracy. The dx² – y² and dz² orbitals, pointing toward ligands, experience more repulsion, resulting in higher energy, while dxy, dyz, and dxz orbitals are lowered in energy.
What causes the removal of degeneracy in the d orbitals of a metal in an octahedral coordination entity, and how is this influenced by the ligand direction?
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The removal of degeneracy in the d orbitals of a metal in an octahedral coordination entity is caused by ligand electron-metal electron repulsions. In octahedral complexes, the metal d orbitals split into higher-energy eg and lower-energy t₂g sets due to the asymmetry of ligand approach. The ligands, positioned along the axes, lead to increased repulsion for the d orbitals pointing towards the ligands (dx² – y² and dz²), raising their energy. Orbitals directed between the axes (dxy, dyz, and dxz) experience less repulsion, lowering their energy. This ligand-induced splitting, known as crystal field splitting, removes the degeneracy of the d orbitals in octahedral complexes.