Ligands and Their Field Strength

Oct 13, 2025 by wbrum.org 117 views

Understanding Ligand Field Strength

Ligand field theory is a fundamental concept in coordination chemistry that explains the splitting of d-orbitals in transition metal complexes. The ligand field strength is a measure of the ability of a ligand to split the d-orbitals of a metal ion. A strong ligand field results in a large splitting of the d-orbitals, while a weak ligand field results in a small splitting. In this article, we will discuss the correct order of increasing ligand field strength among the given options.

Ligands and Their Field Strength

The ligands mentioned in the options are:

S²⁻ (sulfide ion)
OH⁻ (hydroxide ion)
en (ethylenediamine)
edta⁴⁻ (ethylenediaminetetraacetic acid)

Each of these ligands has a unique ability to split the d-orbitals of a metal ion, resulting in different ligand field strengths.

Sulfide Ion (S²⁻)

The sulfide ion is a strong-field ligand, which means it has a high ability to split the d-orbitals of a metal ion. This is due to the high electronegativity of sulfur and the ability of the sulfide ion to form strong covalent bonds with metal ions.

Hydroxide Ion (OH⁻)

The hydroxide ion is a weak-field ligand, which means it has a low ability to split the d-orbitals of a metal ion. This is due to the relatively low electronegativity of oxygen and the ability of the hydroxide ion to form weak covalent bonds with metal ions.

Ethylenediamine (en)

Ethylenediamine is a bidentate ligand that has a moderate ability to split the d-orbitals of a metal ion. This is due to the ability of the nitrogen atoms in the ligand to form strong covalent bonds with metal ions.

Ethylenediaminetetraacetic Acid (edta⁴⁻)

Ethylenediaminetetraacetic acid is a hexadentate ligand that has a high ability to split the d-orbitals of a metal ion. This is due to the ability of the oxygen and nitrogen atoms in the ligand to form strong covalent bonds with metal ions.

Correct Order of Increasing Ligand Field Strength

Based on the discussion above, the correct order of increasing ligand field strength is:

OH⁻ (hydroxide ion)
S²⁻ (sulfide ion)
en (ethylenediamine)
edta⁴⁻ (ethylenediaminetetraacetic acid)

This order is based on the ability of each ligand to split the d-orbitals of a metal ion, with the hydroxide ion being the weakest and the edta⁴⁻ being the strongest.

Conclusion

In conclusion, the correct order of increasing ligand field strength is OH⁻ < S²⁻ < en < edta⁴⁻. This order is based on the ability of each ligand to split the d-orbitals of a metal ion, with the hydroxide ion being the weakest and the edta⁴⁻ being the strongest. Understanding the ligand field strength is crucial in coordination chemistry, as it affects the properties and reactivity of metal complexes.

References

Cotton, F. A., & Wilkinson, G. (1988). Advanced Inorganic Chemistry (5th ed.). John Wiley & Sons.
Housecroft, C. E., & Sharpe, A. G. (2008). Inorganic Chemistry (3rd ed.). Pearson Education.
Atkins, P. W., & De Paula, J. (2010). Physical Chemistry (9th ed.). Oxford University Press.