Nonempirical calculations of NMR indirect spin–spin coupling constants. Part 15: pyrrolylpyridines

Abstract

Conformational study of 2-(2-pyrrolyl)pyridine and 2,6-di(2-pyrrolyl)pyridine was performed on the basis of the experimental measurements and high-level ab initio calculations of the one-bond 13C-13C, 13C-1H and 15N-1H spin-spin coupling constants showing marked stereochemical behavior upon the internal rotation around the pyrrole-pyridine interheterocyclic bonds. Both compounds were established to adopt predominant s-cis conformations with no noticeable out-of-plane deviations.

One‐bond 29Si‐1H spin‐spin coupling constants in the series of halosilanes: benchmark SOPPA and DFT calculations, relativistic effects, and vibrational corrections

“…In all calculations, both at the SOPPA and DFT levels, Sauer's contracted aug‐cc‐pVTZ‐J basis set (derived elsewhere for hydrogen and silicon), which is specially optimized for and very well‐approved in the high‐level correlated calculations of spin‐spin coupling constants, was used for silicon and hydrogens, whereas Pople's 6‐311G** basis set was used for all halogens (F, Cl, Br, and I) throughout. It was expected that Sauer's aug‐cc‐pVTZ‐J basis should provide better performance in the calculations of 1 J (Si,H) due to the improved description of the electron density on the silicon nucleus that is of major importance for the adequate evaluation of the Fermi contact contribution to the total value of spin‐spin coupling constant, as was shown earlier for spin‐spin couplings involving carbon, nitrogen, phosphorous, and selenium . It follows from the data presented in Table that the overall contribution of the non‐contact terms of 1 J (Si,H) is almost negligible in all compounds 1–13 .…”

“…Recently, a major breakthrough has been achieved in the high‐level calculations of different types of spin‐spin coupling constants . In a long chain of our recent publications, we have successfully applied a general second order polarization propagator approach, SOPPA, to calculate element‐hydrogen spin‐spin coupling constants involving carbon, nitrogen, silicon, phosphorous, selenium, and most recently, tellurium . Alternatively, a number of papers reports the implementation of another efficient high‐level non‐empirical method, coupled clusters with single and double amplitudes within the equation‐of‐motion framework, EOM–CCSD, for the accurate calculations of spin‐spin coupling constants of different types (for key references, see reviews).…”

Dependencies of J-Couplings upon Dihedral Angles on Proteins

“…Nowadays, many electronic structure codes include efficient implementations [37][38][39][40][41] of the Ramsey equations [42] for the calculations of nonrelativistic spin-spin coupling constants. A vast number of publications devoted to the calculation of J-couplings can be found in the literature, covering different aspects such as the basis set effects [43][44][45][46][47][48][49][50][51][52][53][54][55], the comparison of wave function versus density functional theory (DFT) methods [56][57][58][59][60], or the choice of exchange-correlation functional in DFT approaches [61][62][63][64][65][66][67][68]. Excellent recent reviews of Contreras [69] and Helgaker [70] cover these particular aspects.…”

Benchmark calculations of 29Si–1H spin–spin coupling constants across double bond

“…Recently, a general Second‐Order Polarization Propagator Approach, SOPPA, has been extensively used for the high‐level calculations of different types of spin–spin coupling constants in the medium‐sized organic molecules. Among others, a good performance of the SOPPA method has been demonstrated for the 1 H– 1 H, 13 C– 1 H and 13 C– 13 C couplings in a large number of saturated carbocycles, nitrogen‐containing heterocycles, and functional derivatives of aldehydes and ketones, the 15 N– 1 H, 15 N– 13 C and 15 N– 15 N couplings in the cyclic and open‐chain nitrogen‐containing compounds, the 19 F– 1 H, 19 F– 13 C and 19 F– 19 F couplings in fluorobenzenes, the X … H … Y (X, Y = 17 O, 15 N, 19 F) couplings across hydrogen bonds, the 31 P– 1 H couplings in organic phosphines and phosphine chalcogenides, the 77 Se– 1 H couplings in selanylalkenes, five‐ and six‐membered selenium‐containing heterocycles, and even in much larger systems like selenosugars . Also, SOPPA(CCSD) approach was successfully employed for smaller systems, presenting a difficult case for methods based on perturbation theory .…”