Question

The sum of coordination number and oxidation number of the metal $M$ in the complex $\left[M \left( en \right)_{2} \left(C_{2} O_{4}\right)\right]Cl$ is ________.

Answer 1

$\left[ M ( en )_2\left( C _2 O _4\right)\right] Cl$
The complex has two molecules of en and one $C _2 O _4^{2-}$ ion. Thus, the complex has three bidentate ligands in all. Coordination number
$=2 \times$ number of bidentate ligands $=2 \times 3=6$ Let the oxidation number of metal ${ }^* M ^{\prime}$ in the complex be ${ }^* x^{\prime}$ The charge on complex ion, en and $C _2 O _4^{2-}$ are $+1,0$ and $-2$ respectively. Hence, $x+0-2=+1 x=3$ The sum of coordination number and oxidation number of the metal $M=6+3=9$