Question

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

• A. $d^4$
• B. $d^9$
• C. $d^7$
• D. $d^8$

Answer 1

The correct option is D $d^8$

The Jahn-Teller effect is a geometric distortion of a non-linear molecular system that reduces its symmetry and energy. This distortion is typically observed among octahedral complexes where the two axial bonds can be shorter or longer than those of the equatorial bonds.

It is present in $d^4$ high spin, $d^7$ low spin and $d^9$ configurations which have odd number of electrons in $e_g$ set.

A weak John-Teller effect is also present in $d^7$ high spin complex which has odd number of electrons in the set. Whereas a $d^8$ high spin complex is symmetric.