${Ni}^{+4} \rightarrow {d}^{6}$ strong field ligand
$[image(1)]$
Pairing will be there zero unpaired electron
${NiCl}_{2} \rightarrow {Ni}^{2+} \rightarrow {d}^{8}$
$[image(2)]$
Change $=2$
${\left[ {V\,{{\left( {CN} \right)}_6}} \right]^{4 - }}$ , ${\left[ {Fe\,{{\left( {CN} \right)}_6}} \right]^{4 - }}$ , ${\left[ {Ru\,{{\left( {N{H_3}} \right)}_6}} \right]^{3 + }}$ , અને ${\left[ {Cr\,{{\left( {N{H_3}} \right)}_6}} \right]^{2 + }}$