Question

The oxidation number of $\mathrm{Pt}$ in the complex ${\left[\mathrm{Pt}\right({\mathrm{C}}_2{\mathrm{H}}_4\left){\mathrm{Cl}}_3\right]}^{-}$is_.

Answer 1

Oxidation number

• "Oxidation number denotes the oxidation state of an element in a compound ascertained according to a set of rules formulated on the basis that electron pair in a covalent bond belongs entirely to a more electronegative element."

Oxidation number of platinum in ${\left[\mathrm{Pt}\right({\mathrm{C}}_2{\mathrm{H}}_4\left){\mathrm{Cl}}_3\right]}^{-}$

• Consider the oxidation number of platinum is $x$.
• Here, the oxidation number of ${\mathrm{C}}_2{\mathrm{H}}_4$ $\left({\mathrm{CH}}_2={\mathrm{CH}}_2\right)$is zero. It is a neutral ligand.
• The oxidation number of chlorine is $-1$.
• The overall charge on the complex is $-1$,so the sum of oxidation states of all elements in it should be equal to $-1$.
• $$\begin{gathered} x+0+\left(-1\times 3\right)=-1 \\ x=-1+3 \\ x=+2 \end{gathered}$$

So, the oxidation number of $\mathrm{Pt}$ in the complex ${\left[\mathrm{Pt}\right({\mathrm{C}}_2{\mathrm{H}}_4\left){\mathrm{Cl}}_3\right]}^{-}$is $+2$.