Crystal Field Theory i Separate metal and ligands
- Slides: 12
Crystal Field Theory i) Separate metal and ligands have high energy ii) Coordinated Metal - ligand get stabilized iii) Metal and Ligands act as point charges. iv) Metal and ligands bond due to strong electrostatic forces of attraction. v) F = q 1 q 2 ( q 1 q 2 – point charges, distance between charges) r 2 vi) Destabilization due to ligand -d electron repulsion
d - orbitals
Ligand-Metal Interaction • Basic Assumption in CFT: • Electrostatic interaction between ligand metal d-orbitals align along the octahedral axis will be affected the most. More directly the ligand attacks the metal orbital, the higher the energy of the d-orbital. In an octahedral field the degeneracy of the five d-orbitals is lifted
Octahedral field
Splitting of d-Orbitals Octahedral Field • Ligands approach metal on the axis d-orbitals pointing directly at axis are affected most by electrostatic interaction d-orbitals not pointing directly at axis are least affected (stabilized) by electrostatic interaction
Splitting in Octahedral field Stage II Hypothetical Stage III
Splitting in Octahedral field Stage I – The free metal ion. Degenerate d- orbitals. Stage II – Hypothetical stage 1. The six ligands create a symmetrical uniform field. 2. All the d orbital experience equal repulsion and their energy get raised equally. 3. Degenerate d- orbitals. Stage III – 1. Ligands create an octahedral field and approach on the axis. 2. The eg , d orbitals oriented along the axis (d x 2 – y 2 and dz 2 ) experience greater repulsion and are repelled more. 3. Degeneracy is lost. 4. Splitting of d orbitals take place, Δo = 10 Dq 5. For every electron entering t 2 g orbital energy equal to 4 Dq is released and every electron entering eg orbital raises the energy equal to 6 Dq.
Splitting in Tetrahedral field z - axis y - axis X - axis
Splitting in Tetrahedral field • Free metal ion • Spherical field • Degenerate d – orbitals • Higher energy • Free metal ion • Degenerate d - orbitals splitting of d – orbitals CFS = Δt
Splitting in Tetrahedral field Stage I – The free metal ion. Degenerate d- orbitals. Stage II – Hypothetical stage – 1. The four ligands create a symmetrical uniform field. 2. All the d orbital experience equal repulsion and their energy get raised equally. 3. Degenerate d- orbitals. Stage III – 1. Ligands create a tetrahedral field. 2. Ligands approach in between the axis. 3. The t 2 g d orbitals oriented in between the axis (dxy, dyz , dxz) experience greater repulsion and are repelled more. 4. Degeneracy is lost. 5. Splitting of d orbitals take place.
Splitting in Square Planar field d x 2 – y 2 Δsp d x 2 – y 2 d z 2 d xy d z 2 d xz d yz State 1 State 2 State 3 State 4 State 5
Splitting in Square Planar field Stage I – The free metal ion. Degenerate d- orbitals. Stage II – Hypothetical stage – 1. The four ligands create a symmetrical uniform field. 2. All the d orbital experience equal repulsion and their energy get raised equally. 3. Degenerate d- orbitals. Stage III – 1. Ligands create an octahedral field. Ligands approach in between the axis. 2. Splitting of d orbitals take place. Stage IV – Orbitals oriented along the x – axis are moved away from the central metal, hence dxz, dyz and dz 2 are lowered in energy. Stage V - Orbitals oriented along the x – axis are removed hence dxz, dyz and dz 2 are further lowered in energy and difference in energy between dxy and dx 2 –y 2 give the crystall field splitting energy.
- Cfse of co(h2o)6 3+
- Teori medan ligan
- Site:slidetodoc.com
- Trigonal bipyramidal crystal field splitting diagram
- Silent features of cft
- Applications of crystal field theory
- Coordination isomerism
- Triamminetriaquachromium(iii) chloride
- Pi donor ligands
- Spectrochemical series of ligands
- Spectrochemical series of ligands
- Spectrochemical series of ligands trick
- Ammonium diamminetetrachlorocobaltate(ii)