Question

Which of the following shall form an octahedral complex?

• A. $d^4$ (low spin)
• B. $d^8$ (high spin)
• C. $d^6$ (low spin)
• D. None of these

Answer 1

The correct option is C $d^6$ (low spin)

In $d^4$ (low spin) and $d^6$ (low spin), electrons get paired up to make two inner d - orbitals empty. Hybridisation is $d^{2}s{p}^3$ (octahedral) and the complex is low spin.

In $d^8$ (high spin), none of inner d - orbitals is empty. Hybridisation is $s{p}^3{d}^2$ (octahedral) and the complex is high spin.