Weixing,
The two 15N signals are chemical shift equivalent but not magnetically equivalent. So, 1H ‘sees’ two magnetically in-equivalent 15N nuclei - one with a one-bond coupling (1JNH) and one with a long-range coupling 3JNH. And vice-versa for observation of 15N.
The pattern you see is actually more than a simple doublet. It’s second-order, more complicated than allowed by simple first-order analysis.
- Ted
On May 14, 2015, at 11:53 AM, Zhang, Weixing <Weixing.Zhang_at_STJUDE.ORG<mailto:Weixing.Zhang_at_STJUDE.ORG>> wrote:
Hello All:
I recorded 1H and 15N spectra of 15N-labeled urea in DMSO.
Both 15N-decoupled 1H and 1H-decoupled 15N spectra have single peak.
Without decoupling, both 1H and 15N spectra show a small splitting of ~4 Hz (see attached pictures).
Does anybody have an explanation of the splitting pattern?
Thanks,
Weixing Zhang
St. Jude Children’s Research Hospital
Memphis, TN 38105
<Urea-15N.jpg><Urea_1H.jpg>
Received on Thu May 14 2015 - 15:29:02 MST