[instawin]

Hello friends, I've attached a simple problem that I came up with myself after a wikipedia dive for some interesting looking molecules - it isn't for school since I have already graduated from college. I'm just trying to dust off the cobwebs with some review before trying to learn orgo on my own.

I'm trying to find the hybridization of particular atoms that I labeled as "O_a", "O_b", "N", "C_a" and "O_c". I thought they were sp2, sp2, sp2, sp3, and sp2, respectively. I felt good about all of these except for O_c because I'm not sure if the last resonance structure I drew in the bottom right is considered valid. Other people told me it is sp3, but since this is a problem I made myself, I dunno if that is actually true.

If O_c is sp3 and if the last resonance structure I drew in the bottom right is also correct, then I'm not sure why this is the case (so I guess there is something wrong with my work). I think I found the hybridization of the others correctly, but I am happy to be corrected.

Also, if you have recommended resources for learning about arrow pushing, I'm all ears.

[mjc123]

The final resonance structure is conceivable, but it would be very high-energy relative to the others, as it is doubly charge-separated and has two positive charges on adjacent atoms. Its contribution to the overall structure would therefore be minimal, and you can ignore it. I would say that Oc is sp³.

[instawin]

The final resonance structure is conceivable, but it would be very high-energy relative to the others, as it is doubly charge-separated and has two positive charges on adjacent atoms. Its contribution to the overall structure would therefore be minimal, and you can ignore it. I would say that Oc is sp³.

Thanks for your input. The way you put it seems logical. Do you have tips for knowing where to draw the line between situations where a structure makes a big enough contribution to call an atom sp2 versus sp3?