On what factors does the crystal field splitting in an octahedral complex depend?

(N/A) The crystal field splitting $\Delta_{o}$ depends on the following factors:
$(i)$ Charge (oxidation state) of the metal ion: $A$ higher charge on the metal ion results in greater crystal field splitting.
$(ii)$ Strength of the ligands: Strong ligands produce strong fields,causing larger splitting of $d$-orbitals,which increases the crystal field splitting. Weak ligands result in smaller crystal field splitting.
The strength of ligands is determined experimentally based on the absorption of light by complexes with different ligands. When these ligands are arranged in a series in increasing order of field strength,it is known as the spectrochemical series:
$I^{-} < Br^{-} < SCN^{-} < Cl^{-} < S^{2-} < F^{-} < OH^{-} < C_{2}O_{4}^{2-} < H_{2}O < NCS^{-} < edta^{4-} < NH_{3} < en < CN^{-} < CO$