Which carbon will resonate more downfield in this molecule?

[muhali3]

In the picture, will carbon 4 or carbon 6 appear more downfield on a C13 NMR spectrum. They are both one carbon away from a nitrogen, I am guessing 4 but I have no logical reason for this answer.

 

Thanks for the help

[Tartaglia]

They are going to be very close frankly.

[louis wu]

No 4 should in theory be more downfield as it has 2x N at 2 atoms removed.

No 2 has 1x N at 2 atoms removed.

 

The difference is unlikely to large as these are not primary factors in fieldshift.

[Geo]

Four, count the groups which the carbons are connected to.

Edited June 3, 2010 by Geo