[fredodgers]

In class, we were doing a review on hybridization and how it can give useful information about the nature of reactions.  In particular, we looked at C2H4O2.  The question was "which oxygen would a metal coordinate with first, the one that has lone pairs that are SP2 hybridized or the ones that has lone pairs SP3 hybridized?"  The answer was SP2 because SP2 is more reactive.  As reasoning, it was said that SP2 is higher in energy.  However, I thought that the more s character an orbital has, the less energy it also has.  Any thoughts?

Thanks

[zsinger]

If I'm not mistaken, your thinking is backwards.  More "s" character equals more reactivity.  Don't quote me though.  Besides…….aren't both oxygens hybridized the same way?  Hope this is helpful.
            -Zack

P.S.-What is your proposed Lewis Formula?  I only can see one?

[PhDoc]

With this type of question, it's best to include a structure, however your formula is simple enough that there are only two practically viable possibilities: acetic acid and methyl formate.

To answer your question, let's first ask a question. In what capacity is the metal cation serving when coordinating with oxygen? Hint - it's in a capacity quite comparable to that served by H+ when protonating an oxygen.

Another question, in what capacity is the oxygen serving when coordinating to either a metal cation or proton?

Another question. When you coordinate the metal cation to the sp3 oxygen, how many resonance structures can you draw? Do the same thing for the sp2 oxygen. How many resonance structures can you draw.

What have you thus far learned of resonance in organic chemistry?