Jahn-Teller effect is not observed in high spin complexes of

Jahn Teller effect (JTE) explains the axial distortion in perfect octahedral geometry. It is present in ${d}^{4}$ high spin, ${d}^{7}$ low spin and ${d}^{9}$ configuration, which have an odd number of electrons in a ${e}_{g}$ set. A weak Jahn Teller effect is also present in ${d}^{7}$ high spin complex, which has an odd number of electrons in the set. Therefore, the Jahn Teller effect is not observed in high spin complexes of ${d}^{8}$ orbital.