Question

In ${\text{N}}{{\text{a}}_{\text{2}}}\left[ {{\text{Fe}}{{\left( {{\text{CN}}} \right)}_{\text{5}}}{\text{NO}}} \right]$, sodium nitroprusside --------.
A. oxidation state of Fe is $+ 2$
B. this has ${\text{N}}{{\text{O}}^{{\text{ - 1}}}}$as ligand
C. both are correct
D. none is correct

Answer 1

As coordination compounds contain a central metal atom or ion surrounded by a number of oppositely charged ions or neutral molecules . So these ions as well as molecules are rebounded to the metal atom or ion by a coordinate bond .

Complete step by step answer:
Firstly , we have to know about sodium nitroprusside , so it is a chemical test which is used to check the presence of thiol groups of cysteine in proteins . When a solution of sodium nitroprusside is added in aqueous ammonia , then proteins with the free thiol groups give a red colour . So for the required answer, calculate the oxidation number of central atom ${\text{N}}{{\text{a}}_{\text{2}}}\left[ {{\text{Fe}}{{\left( {{\text{CN}}} \right)}_{\text{5}}}{\text{NO}}} \right]$
From the compound firstly find the central atom …. Our central atom is ( Fe )iron .
Let X be the oxidation number of iron in ${\text{N}}{{\text{a}}_{\text{2}}}\left[ {{\text{Fe}}{{\left( {{\text{CN}}} \right)}_{\text{5}}}{\text{NO}}} \right]$
Substituting the following values in the compound -
Na${\text{ = + 1}}$ , Fe$=$ X, CN${\text{ = - 1}}$, NO $= + 1$ and the overall charge is ${\text{ = 0}}$
Therefore,
${\text{2}}\left( {{\text{ + 1}}} \right){\text{ + X + 5}}\left( {{\text{ - 1}}} \right){\text{ + 1 = 0}}$
Or ${\text{X = + 2}}$
So, the oxidation number of iron in is ${\text{N}}{{\text{a}}_{\text{2}}}\left[ {{\text{Fe}}{{\left( {{\text{CN}}} \right)}_{\text{5}}}{\text{NO}}} \right]$ $+ 2$.
Fe has an oxidation state of $+ 2$ and ${\text{N}}{{\text{O}}^{\text{ - }}}$ acts as a ligand.
Option (A) and (B) both are the correct options. As we proved the oxidation state of Fe is $+ 2$ and the compound has ${\text{N}}{{\text{O}}^{{\text{ - 1}}}}$ as ligand.

So, the correct answer is Option C .

Note:
Ligands may be neutral, positively and negatively charged. Talking about oxidation number of the central atom so it is defined as the charge that it would carry if all the ligands are removed along with the electron pairs that are shared with the central atom.