Hello Marvin developers
I'm having some trouble generating the H-NMR spectrum of methane (see attachment). The predicted chemical shift is by far too large (4,29ppm) compared to signal observed in the experimental spectrum (0,23 pm). Am I doing something wrong? I am using MarvinSketch ver. 5.11.3 with an acedemic licence.
I got the same value. As our present chemical shift database does not contain this proton shift, we can not retrieve it based on similarity search. Thus, the CH4 proton shift is predicted by our QSPR model fitted to standard organic molecules (all of them are larger than methane and they contain various functional groups), so CH4 is not within the scope of our QSPR model. I have just downloaded 1H and 13C chemical shifts for some frequently used solvents and small molecules (like CH4 or CO2) and I will add these data to our chemical shift database.
I have just completed the fixes I have mentioned in my previous post, Marvin 5.12 will contain them.