Correlated calculations of indirect nuclear spin-spin coupling constants using second-order polarization propagator approximations: SOPPA and SOPPA(CCSD)

Abstract

We present correlated calculations of the indirect nuclear spin-spin coupling constants of HD, HF, H 2 O, CH 4 , C 2 H 2 , BH, AlH, CO and N 2 at the level of the second-order polarization propagator approximation (SOPPA) and the second-order polarization propagator approximation with coupled-cluster singles and doubles amplitudes ± SOPPA(CCSD). Attention is given to the eect of the so-called 4 term, which has not been included in previous SOPPA spin-spin coupling constant studies of these molecules. Large sets of Gaussian basis functions, optimized for the calculation of indirect nuclear spin-spin coupling constants, were used instead of the in general rather small basis sets used in previous studies. We ®nd that for nearly all couplings the SOPPA(CCSD) method performs better than SOPPA.

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

“…Geometric optimizations at DFT level were performed with GAMESS code 120 and all calculations of spin-spin coupling constants at RPA and SOPPA were carried out using the DALTON package, 9,11,121,122 whereas the SOPPA(CCSD) results were obtained with a modified version of the Dalton package. 10,11,30 Both codes, GAMESS and DALTON, were compiled as LFS (Large Files System) versions for Linux.…”

“…On the other hand, only average values of carbon-hydrogen and proton-proton couplings of the specifically deuterated cyclohexane could be measured at ambient temperature owing to the rapid ring inversion; however, low-temperature NMR measurements could resolve individual couplings involving axial and equatorial protons in the frozen chair conformer. This approach was first demonstrated by Garbisch and Griffith, 92 11 by chlorination of cyclohexane-d 12 followed by Grignard replacement of chlorine with hydrogen. The low-temperature proton-coupled 13 C NMR spectrum at 104°C of cyclohexane-d 11 was analyzed as arising from eight non-equivalent frozen conformers depending on whether the single proton is in an axial or equatorial position to yield the full set of the eight possible 'frozen' carbon-hydrogen couplings of cyclohexane as shown.…”

“…This approach was first demonstrated by Garbisch and Griffith, 92 11 by chlorination of cyclohexane-d 12 followed by Grignard replacement of chlorine with hydrogen. The low-temperature proton-coupled 13 C NMR spectrum at 104°C of cyclohexane-d 11 was analyzed as arising from eight non-equivalent frozen conformers depending on whether the single proton is in an axial or equatorial position to yield the full set of the eight possible 'frozen' carbon-hydrogen couplings of cyclohexane as shown. Table 4 for details.…”

“…Along with the standard SOPPA, we use here the socalled SOPPA(CCSD) method, 10,11 providing a combination of classical SOPPA with the CCSD (Coupled Cluster Singles and Doubles) computational scheme to test their relative merits. r iA j 5 …”

“…Previous calculations of polarizabilities 10,31 and in particular of indirect nuclear spin-spin coupling constants 11,32 -34 showed that this is indeed the case. The detailed scheme for calculations of indirect nuclear spin-spin coupling constants using polarization propagator methods has been described and explained previously 11,35 and will not be given here.…”