1. Crystal Field Theory
   1. crystal field theory lecture notes.pdf
   2. Based on electro-static interactions between ligands with d-orbitals
      1. 2 d-orbitals have stronger ligand interaction than the other 3
   3. The negative charge of ligand electron pairs has more interaction with dz2 and dx2-y2
      1. Therefore dz2 and dx2-y2 have higher energy than the 3 other d-orbitals
   4. Filling the Valence electrons of the metal into the split d-levels, we can estimate the color and magnetism of the molecule
      1. Example: compare 2 Ni(II) compounds
   5. Different ligands cause different energy splitting on the same metal center
      1. Topic
      2. Ligands can be ordered for their splitting in the spectochemical series: CO = CN(-) > NH3 > H2O > X(-)
   6. Sometimes distortion of high symmetry has electronic benefit = Jahn Teller Effect
      1. JT Effect octahedral complex
2. Ligand Field Theory
3. MO Theory
4. Group Theory (Symmetry)
5. Center Atom: Transition Metal
   1. Valence electrons are in d-shell
      1. 2 groups: on the axis and between
   2. act as electron acceptor = Lewis acid
   3. s- and d-orbitals have the same energy => we count all valence electrons as d-electrons example: Fe = 8 VE
6. Ligands are electronpair donors (Lewis basis)
   1. Molecules with lone pairs like NH3, PR3, H2O, Cl(-), -O(-)
   2. Molecules with pi-bonds like R2C=CR2
7. 18 electron rule: sum of valence electrons and bonding electrons = 18 is the most stable case
   1. example: Fe(CO)5, [Fe(CN)6](3-),
8. Coordination numbers
   1. mostly octahedral, for Fe and Mn pentagonal, for Ni-group square planar, for Cu-group trigonal or linear