[Super Newb]

Hi all,

As I was reading through an organic chemistry textbook, and it mentions that amidinine is a stronger base as compared to the amines, furthermore by attributing the increase in the basicity to the stabilization of the conjugate acid of the amidinine by the delocalization of the positive charge.

But one can't help but to notice that the delocalization of the positive charge involves the formation of pi bond between the sp3 hybridized Nitrogen and the p-orbital of the sp2 hybridized Carbon.

And this issue raises the following questions:

How is it possible that the sp3 hybridized nitrohgen can form pi-bond with the sp2 hybridized carbon?

I am aware that there is this effect called the hyperconjugation, but can this simply be explained by using this effect?

Or is there an alternative explanation from the molecular orbital theory?


Any help will be greatly appreciated!!

From an avid and keen learner:)

[insertwittyname]

I suppose that even though the hyperconjugation in the amidinine would be weak (due to different orbitals being involved), it'd still be more than that of an amine (no hyperconjugation). In the end it would mostly be  a case of something better than nothing.
However if someone has a better explanation involving MOT, I'd be more than ready to read that as well.
Cheers.

[AdiDex]

Always remember Hybridization concept is just a tool not the reality . So Here is the answer , whatever the structure is given on the left side of the picture, It do not contain pure sp3 hybridized N , If you want to explain it you can say its is in between of Sp3 and sp2 hybridisation . 

Can you tell me what is the hybridization of C in methyl anion (CH₃^- ) and of Right carbon in  Allylic Anion (shown in picture ) .