Non‐empirical calculations of NMR indirect carbon–carbon coupling constants. Part 8—Monocycloalkanes

Abstract

Carbon-carbon and carbon-hydrogen spin-spin coupling constants were calculated in the series of the first six monocycloalkanes using SOPPA and SOPPA(CCSD) methods, and very good agreement with the available experimental data was achieved, with the latter method showing slightly better results in most cases, at least in those involving calculations of J(C,C). Benchmark calculations of all possible 21 coupling constants J(C,C), J(C,H) and J(H,H) in chair cyclohexane revealed the importance of using the appropriate level of theory and adequate quality of the basis sets. Many unknown couplings in this series were predicted with high confidence and several interesting structural trends (hybridization effects, multipath coupling transmission mechanisms, hyperconjugative interactions) were elucidated and are discussed based on the present calculations of spin-spin couplings.

Non‐empirical calculations of NMR indirect carbon–carbon coupling constants. Part 10—Carbocages

“…ased on x-ray, 51 electron diffraction, 52,53 microwave 54 and other spectroscopic data 55 and in conformity with DFT 1,56,57 calculations. In this regard, cubane provides an interesting simulation of hypothetical planar cyclobutane, which is actually a saddle point between two degenerate bent equilibrium structures, as follows from the harmonic vibrational frequency analysis.…”

Non-empirical calculations of NMR indirect carbon-carbon coupling constants. Part 11?saturated carbocycles: a reference data set and a practical guide to structural elucidation

“…1 One-bond, geminal and vicinal J(C,C) in adamantane (49) are very close to those in the chair cyclohexane (given in parentheses are the corresponding couplings in cyclohexane calculated within the same method and basis set):…”

“…Further sophistication of theory achieved by taking into account electronic correlation effects at the SOPPA(CCSD) 13 level results in only a very slight improvement of J(C,C) calculations, as shown for monocycloalkanes. 1 On the other hand, the MCSCF theory traditionally used for the non-empirical calculations of spin-spin couplings seems to be insufficient in terms of the electronic correlation effects accounting for the Fermi contact interaction.…”

Small spiroalkanes: ring strain effects and carbon-carbon spin-spin coupling constants

“…Calculations of spin-spin coupling constants have been carried out taking into account all four non-relativistic coupling contributions with the DALTON package 10 at the SOPPA(CCSD) level using the B3LYP/6-311G* geometries with the correlation-consistent basis set cc-pVDZ augmented with two core s-functions of Woon and Dunning on coupled carbons, as specified elsewhere. 11 The rest of the atoms (uncoupled) were specified with cc-pVDZ without polarization p-functions on hydrogens.…”