# How can you find oxidation numbers in complex compounds?

Aug 21, 2016

Do you mean oxidation numbers in coordination complexes, e.g. ${\left[F e {\left(C \equiv N\right)}_{6}\right]}^{3 -}$, $C o C {l}_{6}^{3 -}$, $C r {\left(C O\right)}_{6}$?

#### Explanation:

You have the starting complex, and its charge. Remove the ligands, with their associated charge, and examine the residual charge on the metal centre, which will be the oxidation state.

${\left[F e {\left(C \equiv N\right)}_{6}\right]}^{3 -} \rightarrow 6 \times N \equiv {C}^{-} + F {e}^{3 +} , \text{ ferric ion}$

${\left[C o C {l}_{6}\right]}^{3 -} \rightarrow 6 \times C {l}^{-} + C {o}^{3 +} , \text{ Co(III)}$.

$\left[C r {\left(C O\right)}_{6}\right] \rightarrow 6 \times C \equiv O + C r \text{ Cr(0)}$.

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