Hybridisation of Mn in MnO4-

  1. What is the hybridisation of manganese in MnO4-
    Configuration of manganese in 3d5 4s2 right? The paired electrons in 4s become unpaired - electron frm it jumps into the 4p orbital
    So now configuration looks like this - 3d5 4s1 4p1
    Now manganese forms 4 sigma bonds and 3 pibonds so the hybridisation should be d2sp and the three d-orbitals form pi bonds
    But apparently this is not the case - hybridisation is sp3
    I dont understand how - it doesnt even have 3 unpaired electrons in p-orbital
    Do the electrons from d-orbital jump to the p-orbital?? But why should they?
     
  2. jcsd
  3. DrDu

    DrDu 4,248
    Science Advisor

    Why shouldn't they jump to the p orbitals. All d, s and p orbitals are nearly degenerate energetically and the electrons distribute so as to minimize energy. You also did take it as granted that the s electron may jump to a p orbital.
    The problem is that when you want to describe bonding in MnO4- by Valence Bond theory you do have to consider resonance between dosens of structures, not only one. Many of them being ionic ones with electrons jumping from Mn to O or the other way round.
    In this situation, it is hardly useful any more to use hybridized orbitals.
    Promoting d electrons to the p orbitals and forming then sp3 hybrids is maybe a possible first approximation. Then you get at least the sigma bonds to the O atoms and you can use the d orbitals for pi bonding.
     
  4. Yeah - but cant the d-orbital electrons form the sigma bond
    Why do they jump to the p-orbital(increase their energy) and then bond.
    They could have stayed in the d-orbital and 2 electrons could have formed sigma bond and other 3 pi bond
     
  5. DrDu

    DrDu 4,248
    Science Advisor

    You can also use sd3 orbitals or something in between sp3 and sd3. However, this is all quite speculative. However I would like to see a calculation from the last 30 years at least for confirmation and there is very little available. I would consider this kind of description of transition metal complexes as quite outdated.
     
  6. @ DrDu
    Sorry i didnt understand - what is outdated?
     
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