The splitting of d-orbitals in a complex depends on the strength of the ligand according to the spectrochemical series. Strong field ligands cause greater splitting, while weak field ligands result in smaller splitting. Among the given complexes:
Thus, the complex \( [\text{Fe(CN)}_6]^{3-} \) will show the largest splitting of d-orbitals due to the presence of cyanide ligands.
A coordination compound holds a central metal atom or ion surrounded by various oppositely charged ions or neutral molecules. These molecules or ions are re-bonded to the metal atom or ion by a coordinate bond.
A coordination entity composes of a central metal atom or ion bonded to a fixed number of ions or molecules.
A molecule, ion, or group which is bonded to the metal atom or ion in a complex or coordination compound by a coordinate bond is commonly called a ligand. It may be either neutral, positively, or negatively charged.