Question

8. The metal orbital portion of MO diagrams for two complexes of Ni2+ are shown below. I I I 11 11 11 1 Ni(NH), Larger 4. Deep blue 11 11 11 14 Ni(H,0)2- Smaller A. Green a. Which has stronger metal-ligand bonding? b. Which will absorb light at longer wavelengths?

Answer 1

Let us define [Ni(NH3)6]2+ as A and [Ni(H2O)6]2+ as B.

A has larger $\Delta o$ than B.

Both A and B has d8 electrons.

CFSE = [(-4*6) + (+6*2)]$\Delta o$ = -12$\Delta o$

Since $\Delta o$ (A) > $\Delta o$ (B) , Magnitude of CFSE(A) > CFSE(B).

So A is more stable than B.

a) So [Ni(NH3)6]2+(A) will have stronger metal ligan bonding.

b) longer wavelength mean less energy, as

E = hc

$\Delta o$(A) > $\Delta o$ (B), So [Ni(H2O)6]2+(B) will absorb at longer wavelength.