Dear All NMR experts,
Thank you so much for your great help and replies for helping me solve the
strange peak which appeared on C13 spectra. I really appreciate your time
and help.
Summary the main thoughts and hypothesis from the replies:
1. It could be a center glitch, which is is due to a small offset in the
two channels used for quadrature detection.
2. It also can be the decoupling of this carbon is incomplete. If the off
resonance of the decoupling pulse is set far away of the extreme resonance
of the bridging OH proton on the cobalxime, it might have such strange
effect.
3. Co-59 has a spin of 7/2 with 100% nature abundance so the 13C/59Co
coupling will split the 13C signal in cases of high symmetry.
So, the first thing I did is that re-run the experiment with shifting the
spectra center 15ppm down field, the strange peak disappears. therefore it
is a center glitch!.
Thanks again for all your replies and help!
Best regards,
Jennifer
On Fri, Jan 11, 2013 at 3:22 PM, Xiaoyan Sun <xsun9_at_ncsu.edu> wrote:
> Dear All NMR experts,
>
> I would like to ask for your expertise to help me solve a puzzle.
>
> We have synthesized a new cobaloxime compound, and there is a strange peak
> appears on the simple 1D C13 spectra at 110ppm. we have assigned the rest
> of carbon peaks. The strange peak should be the Carbon on the ring around
> the Co (which should not be paramagnetic), however the carbon peak present
> as a group of multiple peaks and with both positive and negative
> intensities. What could be possible reason to impact that C13 signal？
> anyone has seen such effect previously?
>
> I have a PDF document for the spectra and the compound, I would be more
> than happy to email you if you would like to take a look.
>
> Thanks
> Jennifer
>
Received on Thu Jan 17 2013 - 07:00:12 MST