||13C Chemical shifts calculated from the EDF2/6-31G* model have been empirically corrected to take account of local environment (bond counts and bond orders). Based on comparisons of a large selection of organic molecules, this lowers the RMS error (to experimental values) from 5.5 ppm to 1.8 ppm. Proton NMR spectra are also available. Three-bond HH coupling constants are estimated empircally based on the 3D geometry.
Unlike purely empirical schemes, iSpartan Server NMR Spectra accounts for both 3D structure (stereochemistry) and conformation.
Calculated NMR Spectra enables users to:
• Assign proton and 13C NMR spectra
• Confirm or challenge structure predictions based on NMR
• Suggest which structure best fits NMR data
• Explore and suggest alternative structures