Question

With help of crystal field energy level diagram, level diagram explain why the complex [cr(en)3]3+ is coloared

Answer 1

To explain:

Why [Cr(en)3]3+ is coloured using Crystal Field Energy diagram.

Explaination:

Crystal Field Energy Diagram refers to arrangement of electrons in divided d orbital in octahedral complex.

$Cr = \{Ar \}4 {s}^{1} 3 {d}^{5}$

Cr in +3 oxidation state :

${Cr}^{ + 3} = \{Ar \}4 {s}^{0} 3 {d}^{3}$

So , it has 3 electrons in the d orbital.

Now , since Ethelyne-diamine is a weak ligant, they electrons would not form pairs, instead they will arrange singly along the t²g part of divided d orbital.

Refer to the attached diagram:

We can see that 3 electrons are arranged singly along the t²g and hence its paramagnetic character shall allow colour production .

[Hence this complex is coloured]