[Rashek]

Hey

So I have this C13 NMR spectrum of Ph₃P-BH₃. And it has several mutiplets - a doublet and two triplets.

Normally this would be fine. But my problem is that this is a proton-decoupled NMR spectrum. So therefore I don't know what to make of this, what is causing the multiplicity and how should I interpret it?

[Corribus]

Carbon and hydrogen may be decoupled but carbon and phosphorus are not.

http://chemwiki.ucdavis.edu/Organic_Chemistry/Organic_Chemistry_With_a_Biological_Emphasis/Chapter_05%3A_Structure_Determination_II/Section_5.8%3A_NMR_of_phosphorylated_molecules

EDIT: Also coupling between carbon and boron.

[Rashek]

Thanks! That makes a lot of sense.

I have an additional question: In an ¹¹B spectrum of the same compound I have a single sextet. The three hydrogen atoms and the phosphorus should only give a quintet right? So where could the sixth peak be coming from?

Is it able coupling with the carbon atoms now - as there is greater probability of 11B being adjacent with 13C than two 13C being adjacent to eachother?

[discodermolide]

¹⁰B is also NMR active.