Sciencemadness Discussion Board

C-H-N and C-H-O interactions

Dr. Beaker - 19-12-2006 at 13:27

Hi everyone,

I'm looking for some info on those interactions.

I made 2 compounds and managed to crystalize them so I got their X-ray structures. in both of them there are 2 molecules as a single asymetric unit, and in one a carbon and his hydrogen of a phenyl ring are almost in line with a nitrogen in a second molecule. there is 2.9 angstrom distans between H and N (if I assume the C-H bond not changed).

in the 2nd case there's a methoxy group in which the oxygen is 2.5 angst. away from a hydrogen sitting on a Me group of a TMEDA moiety (of a second molecule). the 3 atoms are also almost in line.

I have more evidences to support the interaction hypothesis but they're irrelevent to this question.

So, if someone have info on typical C-H-X (X = O,N) bond lengths and angles please tell me.

Thanx in advance!:)

P.s: real sorry I can't give you the full structure becouse it's unpublished data, and a patent candidate.


[Edited on 19-12-2006 by Dr. Beaker]

turd - 19-12-2006 at 15:19

printcif spits out hydrogen-bonding information.
Online version:
http://journals.iucr.org/services/cif/checking/printform.htm...

H...O in hydrogen-bonds is typically around 2Å, angles vary widely. I think 2.5Å or 2.9Å is too far away.
(But I'm not an organic chemist, so I wouldn't know)

Dr. Beaker - 19-12-2006 at 15:33

thanks for the info turd,

as I understand, this site help me make pdf images out of my cif files, but:

a. I don't need it since I see and analyze my files in chem3D
b. I don't want to upload unpublished data to some website.

but thanx anyway.

turd - 19-12-2006 at 19:49

The point is that the program has sensible defaults and will tell you if it thinks that there is hydrogen-bonding. (You were able to locate the protons, isn't it?)

As for your fear of uploading your data: it's the official homepage of the IUCR, you can trust them. If you're still to paranoid, you can try to download an offline version:
http://www.iucr.org/iucr-top/cif/software/index.html

Dr. Beaker - 20-12-2006 at 00:27

that's something else..
I'll give it a try. (to the paranoid version).
thanks again