Which of the following is the most stable complex ion?

Step-by-step solution

The stability of a complex ion depends primarily on the strength of the metal-ligand bonds. The complex [Fe(CO)₅] is a neutral coordination entity, not a complex ion. For the ions [Fe(CN)₆]³⁻ , [Fe(C₂O₄)₃]³⁻ , and [Fe(H₂O)₆]³⁺ , the central metal ion is Fe³⁺ in all cases. The stability is thus determined by the nature of the ligands. According to the spectrochemical series, the field strength of the ligands follows the order H₂O The cyanide ligand ( CN^- ) is a very strong field ligand. It acts as an excellent -don