Question

Among the following pairs of complexes, in which case is the ${\Delta }_0$ value is higher for the first one?

• A. $\left[Co\right(N{H}_3{)}_6{]}^{3+}and\left[Co\right(CN{)}_6{]}^{3-}$
• B. $\left[Co\right(H_2{O}_6{]}^{2+}and\left[Co\right(H_{2}O{)}_6{]}^{3+}$
• C. $\left[Co\right(H_2{O}_6{]}^{3+}>\left[Rh\right(H_{2}O{)}_6{]}^{3+}$
• D. $\left[Rh\right(H_{2}O{)}_6{]}^{3+}and\left[Co\right(H_2{O}_6{]}^{3+}$

Answer 1

The correct option is D

$\left[Rh\right(H_{2}O{)}_6{]}^{3+}and\left[Co\right(H_2{O}_6{]}^{3+}$

${\Delta }_0$ depends on:

(a) strength of ligands $C{N}^{-}>N{H}_3>F^{-}$

(b) Oxidation state of metal; $C{o}^{3+}>C{o}^{2+}$

${\Delta }_0$ also increases down the group due to increasing effective nuclear charge - $Z-eff$.