Does Octet Rule > Formal Chages for atoms that can fill their 3d orbitals?

[FROGGBUSTER]

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Sources often draw the following as the best Lewis structure for SO2:

I'm wondering why this isn't drawn though:

Question:

Sulfur doesn't follow the octet rule, and the formal charges work out more favorably in the second structure. Looking at this example, it seems that fulfillment of the octet rule is more important than favorable distribution of formal charges even in cases where the central atom can fill its 3d orbitals with electrons and surpass an octet.

However, for some reason my instinct are telling me the opposite.

Is this a special case because the first Lewis structure actually has another resonance structure, so you can basically get electron delocalization (a more favorable distribution of charges) as well as fulfill the octet rule?

Normally, I would suspect that we would always try to find the Lewis structure with the most favorable formal charge distribution for central atoms that can go past the octet.

Am I correct?

 

[Rabolisk]

All three structures are correct, and are resonance structures.

http://en.wikipedia.org/wiki/File:Sulfur-dioxide-resonance-2D.png

 

[FROGGBUSTER]

All three structures are correct, and are resonance structures.

http://en.wikipedia.org/wiki/File:Sulfur-dioxide-resonance-2D.png

Yes, I am aware of that, but I thought Lewis structures indicate the distribution of electrons you most often see in a molecule. I think it is implied the structure with 2 double bonds is in a state of higher energy than the other Lewis structure.

 

[salim271]

I can't see the first structure for some reason, but here's my guess why the second one isnt the most stable resonance structure. The pi bonds it forms are simply too weak. Both sulfur and phosphorus can break the octet rule, but when forming pi bonds, they form very weak ones in comparison to something like oxygen or nitrogen. EK didnt explain why (damn concise reviews...) but no doubt it has something to do with number of electrons, distance from the nucleus, etc.

Edit: Checked online, basically the sigma bonds P and S form are very weak already. The pi bonds (which are naturally weaker than sigma ones already) are even weaker.

 

[FROGGBUSTER]

That's very interesting, thank you.