Question

Which one of the following metal complex ions has three unpaired electrons?

A) [Mn(H2O)6]2+ (high spin)

B) [CoCl6]4?(high spin)

C) [MnF6]4? (high spin)

D) [Co(NH3)6]2+ (low spin)

E) [Mn(en)3]2+ (low spin)

Answer 1

Solution :

All the complexes have octahedral geometry. In case of low spin complexes enrgy required to pair electrons in t2g orbitals is less than enrgy required to fill electrons in e2g orbitals so electrons first get paired in lower energy t2g orbital and then remaing electrons goes to e2g orbitals. While in case of high spin complexes enrgy required to pair electrons in t2g orbitals is higher than enrgy required to fill electrons in e2g orbitals so instead of pairing in t2g orbitals electrons first go in e2g orbitals.

So answer is option B [CoCl6]4? (high spin)