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NMR and theoretical investigation of dicylopentadiene derivatives
Author(s) -
Bakke Jan M.,
Brænden Jon Erik,
Krane Jostein
Publication year - 1992
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260300406
Subject(s) - chemistry , mndo , vicinal , norbornane , chemical shift , nmr spectra database , substituent , ring (chemistry) , crystallography , computational chemistry , carbon 13 nmr , isodesmic reaction , stereochemistry , molecular orbital , molecular geometry , spectral line , density functional theory , molecule , organic chemistry , physics , astronomy
Abstract The 1 H and 13 C NMR spectra of endo ‐tricyclo[5.2.1.0 2,6 ]deoane (1‐H), endo ‐tricyclo[5.2.1.0 2,6 ]decan‐2‐ol (1‐OH) and 2‐ endo ‐tricyclo[5.2.1.0 2,6 ]decanyl acetate (1‐OAc) were assigned by the use of 1 H 1 H, 1 H 13 C and 13 C 13 C correlation spectra. The substituent chemical shifts were similar to those observed for the analogous norbornane derivatives. 2 The flip angle of the five‐membered ring and the conformational composition were estimated from the vicinal 1 H 1 H coupling constants. The results were compared with those from molecular mechanics calculations (MMPMI) and semi‐empirical molecular orbital calculations (MNDO). The geometries obtained from the NMR data were close to those from the MMPMI calculations, and the calculated and observed energy differences were within ± 2 kJ mol −1 of each other. The endo conformation of the five‐membered ring was found to be most stable for both 1‐OH and 1‐OAc. The MNDO calculation indicated a close to planar five‐membered ring to be the most stable. This result could not be accommodated with the NMR data.