[Fe(CO)₅] and [Ni(CN)₆] do not show similarity in

participation of d-orbital in hybridization.

Hybridization of Fe in [Fe(CO)₅] is dsp³ while hybridization of Ni in [Ni(CO)₄] is sp³.

\([Fe(CO)_5]\)

\(CO\) is a strong field ligand hence pairing occurs.

\([Ni(CO)_4]\)

The electronic configuration of Ni is

\(Ni = _{18}Ar]4s^2 3d^8\)

After pairing

Hence, in \([Ni(CO)4]\), there is no participation of d-orbital in hybridization.