CHEM 110 Lecture Notes - Lecture 35: Crystal Field Theory, Valence Bond Theory, Coordinate Covalent Bond

• School: McGill University
• Department: Chemistry
• Course: CHEM 110
• Professor: Laura Pavelka

Document Summary

Same composition of complex, ligand donor atom is different. Treat coordinate covalent bond like a single covalent bond. 2 unpaired d electrons pair up, left with one empty d orbital. Problem, cannot explain why compounds are coloured. Certain paramagnetic compounds, theory cannot correctly predict the magnetic properties. Each ligand is treated as a point negative charge. D orbitals are degenerate (same energy) and repel each other. In cft as ligands align, the d orbitals do not remain degenerate. Certain orbitals aligned along axes will have stronger repulsion. 2 high energy orbitals, 3 low energy orbitals. Splitting into 2 levels is the crystal field effect . Low energy 2 orbitals, high energy 3 orbitals. Absorption and reflection of particular wavelengths 400-700 nm (visible range) Reflects what we observe, absorbs complimentary colour. All different complexes had different energy differences, with the same metal ion. Ligand energy difference, certain ligands cause high repulsion=strong field ligands.