discuss briefly why the d orbital splitting is larger in octahedral complex than in tetrahedral one.

Dear student 

For octahedral complexes, crystal field splitting is denoted by  Δo  (or  Δoct ). The energies of the  dz2  and  dx2−y2  orbitals increase due to greater interactions with the ligands. The  dxy ,  dxz , and  dyz  orbitals decrease with respect to this normal energy level and become more stable.

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