Question

If a complex $\left[M\right(H_{2}O{)}_6{]}^{2+}$ absorbs energy corresponding to $\lambda nm$, then the wavelength (in nm) absorbed by tetrahedral complex, $\left[M\right(H_{2}O{)}_4{]}^{2+}$ will be :

• A. $\frac{4}{9}\lambda$
• B. $\frac{5}{9}\lambda$
• C. $\frac{9}{4}\lambda$
• D. $\frac{1}{\lambda }$

Answer 1

The correct option is C $\frac{9}{4}\lambda$

In coordination complex,
Energy is directly related to $\Delta$ (splitting energy ) and inversely to $\lambda$.
$\Delta =\frac{1}{\lambda }$
It is known that
${\Delta }_t=\left(4/9\right){\Delta }_o$
Thus,
$\frac{1}{{\lambda }_t}=\left(4/9\right)\frac{1}{{\lambda }_0}$
Hence, ${\lambda }_t=\frac{9}{4}{\lambda }_0$.
The wavelength absorbed by tetrahedral complex will be $\frac{9}{4}\lambda$ .