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Evidences for covalent bonding in the complexes
This document discusses evidence for covalent bonding in metal complexes. It explains that electron-electron repulsion is less in complexes than free metal ions due to delocalization of electrons over ligand orbitals. This is known as the nephelauxetic effect. The nephelauxetic parameter (β) quantifies this effect, with softer ligands having a smaller β value. Electron paramagnetic resonance (EPR) spectroscopy provides further evidence, as the spectra of complexes show interaction between the ligand nuclear spin and electrons of the metal ion.
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Introduction to covalent bonding in complexes, indicating the role of ligand orbitals in metal coordination.
Describes the nephelauxetic effect where electron repulsion decreases in complexes due to electron delocalization.
Introduces the nephelauxetic parameter (β), its calculation, and the correlation between ligand softness and the parameter's value.
Basics of EPR, highlighting the ms states and their importance in understanding electron configurations.
Discusses the hyperfine splitting observed in EPR spectra of complexes and interaction between nuclear spin and free electrons.
Evidences for covalent bonding in the complexes
- 1. Ligand orbital Evidences forCovalent bonding in complexes Dr. Mithil Fal Desai Shree Mallikarjun and Shri Chetan Manju Desai College Canacona Goa metal orbital
- 2. Nephelauxetic effect Electron-electron repulsionin the complexes is less than that of free metal ion due to expansion of electron cloud. This is caused by delocalisation of electron over ligand orbitals. metal orbital Free metal ion Complex ion Ligand orbital
- 3. Nephelauxetic parameter (βor h) 𝜷 = 𝑩(𝒄𝒐𝒎𝒑𝒍𝒆𝒙) 𝑩(𝒇𝒓𝒆𝒆 𝒊𝒐𝒏) B= Racah parameter (repulsion energies between individual d electron). β is in order Br-< CN-,Cl < NH3 < H2O < F- Softer the ligand smaller will be the nephelauxetic parameter
- 4. Electron paramagnetic resonance (EPR) ms= -½ ms = +½ B0
- 5. Hyperfine splitting inEPR spectra of the complexes ms = +½ ms = -½ ml = -½ ml = -½ ml = +½ ml = +½ Externalmagneticfield Withmagneticnucleus Energy The EPR spectra of the complexes show there is interaction of nuclear spin of ligand with free electrons metal ion. Free metal ion Complex ion Signal Magnetic field strength