Question

In which of the following coordination compounds, the central metal iron is in zero oxidation state?

• A. $\left[Fe\right(H_{2}O{)}_6]C{l}_3$
• B. $K_4\left[Fe\right(CN{)}_6]$
• C. $\left[Fe\right(CO{)}_5]$
• D. $\left[Fe\right(H_{2}O{)}_6]C{l}_2$

Answer 1

The correct option is C $\left[Fe\right(CO{)}_5]$

In $\left[Fe\right(H_{2}O{)}_6]C{l}_3$,as $H_{2}O$ is neutral so its oxidation number is 0 and $Cl$ has -1 oxidation number.So oxidation number of $Fe$ is $(x+6(0)+3(-1)=0,x=+3)$ is +3.

In $K_4\left[Fe\right(CN{)}_6]$,as $CN$ has -1oxidation number and $K$ has +1 oxidation number.So oxidation number of $Fe$ is $\left(4\right(+1)+x+6(-1)=0,x=+2)$ is +2.

In $\left[Fe\right(CO{)}_5]$,as $CO$ is neutral so its oxidation number is 0.So oxidation number of $Fe$ is $(x+5(0)=0,x=0)$ is 0.

In $\left[Fe\right(H_{2}O{)}_6]C{l}_2$,as $H_{2}O$ is neutral so its oxidation number is 0 and $Cl$ has -1 oxidation number.So oxidation number of $Fe$ is $(x+6(0)+2(-1)=0,x=+2)$ is +2.

So C is correct answer.