For complex ion/compound formation reactions
$\text{ (I) }{\mathrm{Co}}^{3+}\left(\mathrm{aq}\right)+{\mathrm{EDTA}}^{4-}⟶\mathrm{P}$
$\text{ (II) }{\mathrm{Ni}}^{2+}\left(\mathrm{aq}\right)+\mathrm{dmg}\text{ (excess) }\stackrel{{\mathrm{NH}}_4\mathrm{OH}}{⟶}\mathrm{Q}$
$\text{ (III) }{\mathrm{Zn}}^{2+}\left(\mathrm{aq}\right)+\text{ gly (excess) }⟶\mathrm{R}$
$\text{ (IV) }{\mathrm{Pt}}^{4+}\left(\mathrm{aq}\right)+\text{ en (excess) }⟶\mathrm{S}$
Which of the following complex ion/compound does not exhibit optical activity ?