Question

In which one of the following, d-d transition involves absorption in the ultraviolet region

• A. [Cu(H$_2$O)$_4$]$^{2+}$
• B. [Ti(H$_2$O)$_6$]$^{3+}$
• C. [Co(NH$_3$)$_6$]$^{3+}$
• D. [Co(CN)$_6$]$^{3-}$
• E. [Co(NH$_3$)$_5$Cl]$^{2+}$

Hint:

Stronger ligand → larger $\Delta$ → higher energy → UV absorption.

Answer 1

The Correct Option is D