Which of the following complexes is responsible for the brown colour of the ring formed in the ring test for the nitrates?

Options

A. `[Fe(H_(2)O)_(5)NO]^(2+)`
B. `[Fe(CN)_(5)NO]^(2+)`
C. `[Fe(H_(2)O)_(5)NO]^(3+)`
D. `[Fe(CN)_(5)NO]^(3+)`

Answer

1

Explanation

Nitric oxide readily forms coordination complexes with transition metal ions . These conplexes are called nitrosyls. In aqueous medium ,`Fe^(2+)` and `NO` from the complex `[Fe(H_(2)O)_(5)NO]^(2+)`, which is responsible for the colour in the 'brown -ring test' for nitrates.
The `No` molecules often acts as a three-electrons donor in contrast to most logands which donate two electrons.