Specify the oxidation numbers of the metals in the following coordination entities:
Specify the oxidation numbers of the metals in the following coordination entities:

(i) \left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)(\mathrm{CN})(\mathrm{en})_{2}\right]^{2+}
Ans: Let us assume that the coordination number of Co is X.
Therefore, we can write:

    \[\begin{array}{l} x+0+(-1)+2(0)=+2 \\ x-1=+2 \\ x=+3 \end{array}\]

So, the coordination number of cobalt is +3.