# Is thiocyanate ion a test for ferric ion?

Thiocyanate ion is a test for the ferric ion, $F {e}^{3 +}$.
Addition of sodium thiocyanate to ferric salts gives the blood-red complex, ${\left[F e \left(N = C = S\right) {\left(O {H}_{2}\right)}_{5}\right]}^{2 +}$. I think the ligand binds thru the nitrogen.
And $C {o}^{2 +}$ gives a blue complex. This was in fact used as a screening test for the presence of cocaine (i.e. it is used in the field, because it gives a visual determination). Only problem is that such a test for coke is completely unreliable, and a lot of people were wrongly arrested on the basis of this test.