Question

In which of the following complexes the nickel metal is in highest oxidation state?

• A. $Ni(CO{)}_4$
• B. $K_{2}Ni{F}_6$
• C. $\left[Ni\right(N{H}_3{)}_6\left]\right(B{F}_4{)}_2$
• D. $K_4\left[Ni\right(CN{)}_6]$

Answer 1

The correct option is B $K_{2}Ni{F}_6$

$\left[Ni\right(CO{)}_4]$ carbonyl is a neutral ligand. So the oxidation state of nickel is 0.

$K_2\left[Ni{F}_6\right]$ fluoro is anionic ligand with -1 charge. So the oxidation state of nickel is +4.

$\left[Ni\right(N{H}_3{)}_6\left]\right(B{F}_4{)}_2$ ammine is neutral ligand and $B{F}_4$ has -1 charge. So the oxidation state of nickel is +2.

$K_4\left[Ni\right(CN{)}_6]$ cyano is anionic ligand with charge -1. So the oxidation state of nickel is +2.