The three-dimensional configuration of the ester heterocycle is basically the same as that of the carbocycle. Compound: 2,4-Dimethyl-1H-pyrrole(SMILESS: CC1=CNC(C)=C1,cas:625-82-1) is researched.Formula: C6H6FNO. The article 《The best density functional theory functional for the prediction of 1H and 13C chemical shifts of protonated alkylpyrroles》 in relation to this compound, is published in Journal of Computational Chemistry. Let’s take a look at the latest research on this compound (cas:625-82-1).
The prediction of 13C chem. shifts can be challenging with d. functional theory (DFT). In this study 39 different functionals and three different basis sets were tested on three neutral alkylpyrroles and their corresponding protonated species. The calculated shielding constants were compared to exptl. data and results from previous calculations at the MP2. We find that the meta-hybrid functional TPSSh with either the Pople style basis set 6-311++G(2d,p) or the polarization consistent basis set pcSseg-1 gives the best results for the 13C chem. shifts, whereas for the 1H chem. shifts it is the TPSSh functional with either the 6-311++G(2d,p) or pcSseg-2 basis set. Including an explicit solvent mol. hydrogen bonded to NH in the alkylpyrroles improves the results slightly for the 13C chem. shifts. On the other hand, for 1H chem. shifts the opposite is true. Compared to calculations at the MP2 level none of the DFT functionals can compete with MP2 for the 13C chem. shifts but for the 1H chem. shifts the investigated DFT functionals are shown to give better agreement with experiment than MP2 calculations
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