Question

The stabilisation of coordination compounds due to chelation is called the chelate effect. Which of the following is the most stable complex species?
(a) $\left[Fe\right(CO{)}_5]$
(b) $\left[Fe\right(CN{)}_6{]}^{3-}$
(c) $\left[Fe\right(C_2{O}_4{)}_3{]}^{3-}$
(d) $\left[Fe\right(H_{2}O{)}_6{]}^{3+}$

Answer 1

Answer: (c). Chelation (formation of a cycle by the linkage between the metal ion and ligand stabilities the coordination compound. The ligand which chelates the metal ion is known as the chelating ligand.
Here, only $\left[Fe\right(C_2{O}_4{)}_3{]}^{3-}$ is a coordination compound which contains oxalate ion as a chelating ligand. Hence, it stabilises the coordination compound by chelating $F{e}^{3+}$ ion.