splitting of d-orbitals

In an octahedral environment, such as a transition metal surrounded by six ligands, the five d-orbitals split into two energy levels due to the electrostatic interactions. Four orbitals (d_xy, d_xz, d_yz, d_x^2−y^2) experience increased repulsion and are higher in energy; this group is called the eg set. The remaining orbital (d_z^2) and the lower-energy set (t2g: d_xy, d_xz, d_yz) experience less repulsion. This splitting influences properties like colors and magnetism, as electrons fill these orbitals differently depending on their energy levels.