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Bioinorganic (Chemical Bonding In Transition Metal Complexes (Electronic…

- - - - ligands are charges
    - - implements electronic structure of ligands and chemical bonding
    - - influence of chemical bond on spectroscopic and magnetic properties
  - - - Lewis acids accept electrons
      - Lewis basis donate electrons
      - when donnation occurs,coordination bond is forming and result structure is an adduct
  - - - 3t2g,1eg
      - d orbitals are splitted, 4 unpaired electrons
    - - 4 t2g
      - d orbitals are splited electrons doubly occupying 3 d orbitals
  - - - Exchabnge energy(K)
        
        K is the difference between two configuration one with parallele electrons on the separate orbitals(repulsion is stronger) comparing to anti-parallel electorns on the sep. orbitals
  - - - 1 electron occupies eg dz2 orbital, this causes to biqger electrostatic repulson between two axial ligands than with other 4 and the axial bonds become elongated
      - if 1 electron occupies eg dx2-y2 equatorial bonds become elongated
      - when t2g orbitals are singly occupied the distortion almost does not occur as the orbitals do not poin on ligands
    - - Any non-linear molecular system in a degenerate electronic state will be ustable and will undergo distortion to form a system o lower symmetry and lower energy and in this way to remove the degeneracy
      - from Oh to D4h
    - - each d orbital which has a z component is stabilized, while other are destabilized
      - this is increasing ligand field strength
  - - - only LGOs which can fit to the same group of symmetry to the whole molecule are allowed
      - AOs must be the same symmetry to interact
  - - - LMCT
        
        ligad is easy to be oxidized and the metal is easy to be reduced
      - MLCT
        
        corresponds to oxidation of the metal and reduction of the ligand
        
        presence of pi-pi star(must be lower - ligand center transition) unocuppied orbital is preferable - CO, py(pyridine), bpy, phen(phenanthroline?), other heterocyclic aromatic ligands.
      - intense absorptions spectra may arise from:
        ligand-based n-pistar transition;
        ligand-based pi-pistar transition;
        transfer of electron between ligand and metal
    - - 1)Spin selection rule
        
        delta S - electron should not change its spin during electronic transition
        
        change of mulitplicity(M) is forbidden
      - 2)Laporte selsction rule
        
        the parity of the orbitals need to be changed
        g<>u(isallowed)
        g<>g u<>u(is forbidden)
        
        quantum number l has to change by +1 or -1
      - exceptions
        
        spin-orbit coupling effect - 'd-d' bands in their electronic
        absorption spectra
- - - - concentration of paramagnet
      - structural characterization: identification of ligands based on ligand-hyperfine;
        interaction of atoms in their first-coordination sphere
      - ident. type of bonding involved based on its central hyperfine interaction
      - determing the saturation binding of a metal ion to a specific site on the protein