Problem 58 - Chemistry: The Central Science

Question

A classmate says, "A strong-field ligand means that the ligand binds strongly to the metal ion." Is your classmate correct? Explain.

Step-by-Step Solution

Answer

Your classmate's statement is not entirely correct. A strong-field ligand refers to its effect on the ligand-field splitting energy in transition metal complexes, but it does not necessarily mean that the ligand binds strongly to the metal ion. The strength of binding depends on various factors, such as the nature of the bond, electronegativity of the ions, and their sizes.

Step 1: Understanding Strong-Field Ligands

Strong-field ligands are those that have a relatively large ligand-field splitting energy, which causes a greater energetic split between d-orbitals involved in metal-ligand bonding in transition metal complexes. The ligand-field splitting energy is a measure of the energy required to promote an electron from the lower-energy d-orbitals (t2g) to the higher-energy d-orbitals (eg). The greater the ligand-field splitting energy, the greater the energy difference between the two sets of d-orbitals.

Step 2: Strength of Binding

The strength of binding between a ligand and a metal ion is primarily determined by the nature of the bond they form, which could be ionic, covalent, or coordinate covalent (dative). Stronger bonds are generally associated with higher bond dissociation energy, which means more energy is required to break the bond between them.

Step 3: Relation between Strong-Field Ligands and Binding Strength

The term "strong-field ligand" refers to the ligand's effect on the ligand-field splitting energy, but it does not necessarily imply that the ligand binds strongly to the metal ion. A strong-field ligand can affect the energy difference between the d-orbitals, but it is not directly related to the bond strength between the ligand and the metal ion. The binding strength of a ligand to a metal ion often depends on other factors, such as electronegativity, the size of the ion, and the type of bonding involved.

Step 4: Conclusion

Your classmate's statement is not entirely correct. A strong-field ligand means that it causes a greater ligand-field splitting energy in the transition metal complex, but it does not necessarily mean that the ligand binds strongly to the metal ion. The strength of binding depends on various factors, such as the nature of the bond, electronegativity of the ions, and their sizes.