Question

In the complex $\left[CoC{l}_2\right(en{)}_2]Br$ the co-ordination number and oxidation state of cobalt are:

• A. $6\text{and}+3$
• B. $3\text{and}+3$
• C. $4\text{and}+2$
• D. $6\text{and}+1$

Answer 1

The correct option is A $6\text{and}+3$

Let $x$ be the oxidation state of cobalt in $[CoC{l}_{2}e{n}_2{]}^{+}.$
So, $x+2(-1)+0=+1$
$\Rightarrow x=+3$.
As there are six $\sigma$ - bonds between cobalt and ligands, its coordination number is $6$ here $en$ is bidentate ligand.