Which statement regarding ligand substitution reactions of transition metal complexes is not correct?
When excess aqueous ammonia is added to an aqueous solution containing [Cu(H2O)6]2+[\text{Cu}(\text{H}_2\text{O})_6]^{2+}[Cu(H2O)6]2+, a deep blue solution is formed containing the octahedral complex ion [Cu(NH3)4(H2O)2]2+[\text{Cu}(\text{NH}_3)_4(\text{H}_2\text{O})_2]^{2+}[Cu(NH3)4(H2O)2]2+.
The addition of excess concentrated hydrochloric acid to a solution containing pink [Co(H2O)6]2+[\text{Co}(\text{H}_2\text{O})_6]^{2+}[Co(H2O)6]2+ ions produces a blue solution containing [CoCl4]2−[\text{CoCl}_4]^{2-}[CoCl4]2− due to a change in geometry from octahedral to tetrahedral.
The reaction of [Fe(H2O)6]3+[\text{Fe}(\text{H}_2\text{O})_6]^{3+}[Fe(H2O)6]3+ with the multidentate ligand EDTA4−\text{EDTA}^{4-}EDTA4− is thermodynamically highly favourable primarily because of a highly exothermic enthalpy change (ΔH⊖≪0\Delta H^\ominus \ll 0ΔH⊖≪0) arising from the formation of much stronger coordinate bonds.
The substitution of water ligands in [Fe(H2O)6]3+[\text{Fe}(\text{H}_2\text{O})_6]^{3+}[Fe(H2O)6]3+ by three bidentate ethanedioate ligands (C2O42−\text{C}_2\text{O}_4^{2-}C2O42−) to form [Fe(C2O4)3]3−[\text{Fe}(\text{C}_2\text{O}_4)_3]^{3-}[Fe(C2O4)3]3− results in an increase in entropy because the number of species in solution increases from four to seven.
