Question

Which of the following complex ions is expected to absorb
visible light?
(a) [Ti (en)₂NH₃)₂]⁴⁺ (b) [Cr (NH₃)₆]³⁺
(c) [Zn (NH₃)₆]²⁺ (d) [Sc (H₂O)₃ (NH₃)₃]³⁺
(At. no. Zn = 30, Sc = 21, Ti = 22, Cr = 24)

Answer 1

Answer:

Hi !

Well the only coordination complexes which do not absorb visible light are complexes in which the central metal atom has completely empty or completely filled d orbital , this is because then no d-d transition of electrons can take place and hence no ability to project out a complementary colour.

Hence, from the given options

Ti4+ will have no d electrons it'll be 3d 0

Cr3+ will have 3d 3 electrons so it'll have ability to show d-d transition.

Zn2+ will have 3d 10 configuration and hence not show d-d transition.

Sc3+ will have no d electrons too it'll be 3d 0 and hence only Cr3+ option B will be the complex which will have ability to absorb visible light.