Question

Which of the following statements is/are true for the complexes, $\left[Fe\right(H_{2}O{)}_6{]}^{2+},\left[Fe\right(CN{)}_6{]}^{3-},\left[Fe\right(C_2{O}_4{)}_3{]}^{3-}$ and $\left[Fe\right(CO{)}_5]$?

• A. only $\left[Fe\right(C_2{O}_4{)}_3{]}^{3-}$ show optical isomerism
• B. $\left[Fe\right(C_2{O}_4{)}_3{]}^{3-}$ is less stable than $\left[Fe\right(CN{)}_6{]}^{2-}$
• C. All complexes have same effective atomic number
• D. $\left[Fe\right(CO{)}_5]$ shows back bonding

Answer 1

Answer: (A), (D)

The correct options are
A

only $\left[Fe\right(C_2{O}_4{)}_3{]}^{3-}$ show optical isomerism

D

$\left[Fe\right(CO{)}_5]$ shows back bonding

$\left[Fe\right(H_{2}O{)}_6{]}^{2+},\left[Fe\right(CN{)}_6{]}^{4-}$ do not show optical isomerism because of the presence of plane of symmetry as well as centre of symmetry

(b) $\left[Fe\right(C_2{O}_4{)}_3{]}^3$ has three, five member chelating rings and thus is more stable due to chelation

(c) $\left[Fe\right(H_{2}O{)}_6{]}^{2+};EAN=26-2+12=36$

$\left[Fe\right(CN{)}_6{]}^{4-};EAN=26-2+12=36$

$\left[Fe\right(C_2{O}_4{)}_3{]}^{3-};EAN=26–3+12=35$

(d) $Fe\underset{\sigma }{\stackrel{\Delta }{\rightleftharpoons }}CO$