Premium
A theoretical study of inversion barriers and NMR chemical shifts of 3‐pyrazolines (2,3 ‐dihydro‐1 H ‐pyrazoles)
Author(s) -
Alkorta Ibon,
Elguero José
Publication year - 2021
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.4235
Subject(s) - chemical shift , chemistry , computational chemistry , inversion (geology) , stereochemistry , crystallography , paleontology , structural basin , biology
A rather neglected family of heterocyclic compounds, the 3‐pyrazolines or 2,3‐dihydro‐1 H ‐pyrazoles, has been studied theoretically at the B3LYP/6–311++G(d,p) level to obtain geometries and energies and at the GIAO/B3LYP/6–311++G(d,p) level for NMR chemical shifts. The calculated barriers of inversion of the N ‐substituents reproduce adequately the scarce experimental data. The calculated 1 H and 13 C chemical shifts are consistent with those reported in the literature. A combination of both results, geometries, and 13 C chemical shifts, shed light on the conformation of N ‐phenyl groups.