Question

Which one of the following complexes is violet in colour?

Options

• \[\ce{[Fe(CN5)NOS]^4-}\]

• \[\ce{Fe4[Fe(CN)6]3 H2O}\]

• \[\ce{[Fe(SCN)6]^4-}\]

• \[\ce{[Fe(CN)_6]^4-}\]

Answer 1

\[\ce{[Fe(CN5)NOS]^4-}\]

Explanation:

\[\ce{[Fe(CN5)NOS]^4-}\] is violet in colour which is formed during detection of element S.

\[\ce{\underset{sulphide}{\underset{Sodium Nitroprusside}{Na2S + Na2 [Fe(CN)5NO]}} -> \underset{thionitroprusside}{\underset{Sodium}{Na4 [Fe(CN)5 NOS]}}}\]