I do an 1H-RMN spectra and I see two differents J in my doublets, the first one is 12.8Hz and the second one 9.8 Hz. How I can assign to the cis- or trans- isomer? Is there any database where I can look for?
Thank you for your time
It depends entirely on your complex and the type of ligands present in, I prefer if you can send me your 1H spectrum and the formula of your complex then we can see which is the cis and which is the trans.
Regards
Subhi
Hi Elisa,
These couplings constant (J) depend on the angles and distances of the nuclei involved. trans J-couplings are usually larger than the corresponding cis .Therefore that equal 12.8 is for trans.Regards.
If I see the 1H spectrum of the structure together with the formula I may interpret cis/trans isomers. As expressed above J-trans coupling are larger than the corresponding cis values.
Regards
Very simple analysis by IR spectroscopy : see infrared andRaman spectroscoy by Nakamoto
The J-coupling for trans is larger than that of cis-isomer. IR will help you to see if it is cis or trans.
All the previous answers are correct but without more information about the molecule it is not possible to give the final answer. Are the couplings between protons or between protons and another nucleus. Please post the spectrum with the proposed structure.
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