$\left[{\mathrm{CrCl}}_3{\left({\mathrm{NH}}_3\right)}_3\right] + {\mathrm{NH}}_3 \to \left[{\mathrm{CrCl}}_2{\left({\mathrm{NH}}_3\right)}_4\right] + {\mathrm{Cl}}^{-}$

if two isomers are possible as products in this reaction, then comment on the form of the reactant complex