This is a question that has bothered me for some time. I have always thought that the part of one molecule will only attack part of another molecule if it has a higher positive charge. So with this in mind, why does the alkene double bond attack the $\ce{O}$ atom of $\ce{OsO4}$. Isn’t the $\ce{O}$ atom negatively charged?

  • 1
    $\begingroup$ I am not sure whether it is the alkene that initiates bond formation. However, take a look at the mechanism. It is a cycloaddition. For all we know, the oxygen from the osmium tetroxide may be the one initiating the formation of the bond. I will try to look some journals and post what I find. $\endgroup$ – CoffeeIsLife Dec 8 '16 at 4:29
  • 4
    $\begingroup$ Not all reactions are driven by simple attraction of oppositely charged atoms. Consider alkene hydrogenation, acetylene trimerization, or the Diels–Alder thing. $\endgroup$ – Ivan Neretin Dec 8 '16 at 5:59

I have a suggestion that could explain the attacK of electron pair of alkene pi bond to the oxygen of osmium tetroxide : The electron pair of alkene pi bond repels the electron density of the oxygen when the osmium tetroxide approaches the alkene, creating a temporary δ+ on the oxygen that is closer to the pi bond of alkene. The electron-rich alkene then attacks the electron-poor oxygen.

Dimitrios Kariotoglou

  • 2
    $\begingroup$ Are these your opinions? Please put in references to literature, or else the answer is just speculation. And this explanation seems quite far-fetched to me. I could be wrong, but the right way to refute my disapproval will be to find literature and add it in. Good-day. $\endgroup$ – William R. Ebenezer Apr 16 '20 at 9:25

Yes. But check the formal charge on the Osmium. It is so very positive that it actually steals electron density from the Oxygen.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.