Скачать с ютуб Crystal field theory | coordination compound |Class-xii | Nikhil sir в хорошем качестве

Crystal field theory | coordination compound |Class-xii | Nikhil sir

Crystal Field Theory (CFT) is a model that explains the electronic structure of transition metal complexes. It describes how the presence of surrounding ligands affects the energy levels of the d-orbitals of the metal ion. Here’s a brief overview: 1. Ligands: These are ions or molecules that donate electron pairs to the metal ion. They can be classified as strong field (e.g., CN⁻, CO) or weak field (e.g., H₂O, Cl⁻) ligands based on their ability to split d-orbital energies. 2. d-Orbital Splitting: In an isolated transition metal ion, the five d-orbitals are degenerate (have the same energy). However, when ligands approach the metal ion, they create an electric field that causes these orbitals to split into different energy levels. 3. Octahedral and Tetrahedral Complexes: The most common geometries are octahedral (six ligands) and tetrahedral (four ligands): Octahedral: The d-orbitals split into two sets—lower-energy \( t_{2g} \) (dxy, dyz, dxz) and higher-energy \( e_g \) (dx²-y², dz²) orbitals. Tetrahedral: The splitting is opposite, with the \( e \) set (dxy, dyz) at a lower energy and the \( t_2 \) set (dx²-y², dz²) at a higher energy. 4. Crystal Field Stabilization Energy (CFSE): The difference in energy between the filled and empty d-orbitals determines the stability of the complex. Strong field ligands lead to larger splitting and can result in low-spin configurations, while weak field ligands may lead to high-spin configurations. 5. Magnetism: The electronic arrangement influenced by ligand field strength also affects magnetic properties. Low-spin complexes can be diamagnetic (no unpaired electrons), while high-spin complexes are often paramagnetic (with unpaired electrons) CFT helps in understanding various properties of transition metal complexes, including color, magnetic behavior, and reactivity. It forms the basis for more advanced theories like Ligand Field Theory and Molecular Orbital Theory.