Quantum-Chemical Characterization of Nuclear Spin−Spin Couplings Across Hydrogen Bonds

The Effect of Substituents on Indirect Nuclear Spin-Spin Coupling Constants: Methan- and Ethanimine, Methanal- and Ethanaloxime

“…The CH 3 From Table 2 we can see that OH substituent effect on the SD, FC and even the OP term becomes larger when we keep the angles in the H 2 C-group in 2 at the same values as in 1, i.e. there is also a geometry effect which opposes the mesomeric effect of the OH group.…”

“…Often these molecules are too large for accurate calculations and many authors [2][3][4][5][6][7][8][9][10][11] make therefore use of model-systems which are supposed to include the relevant atoms, e.g. the atoms involved in peptide bonds.…”

Review on DFT and ab initio Calculations of Scalar Coupling Constants

“…In cases were the proton is shared between A and B the distinction between 1 J AH and 1h J B···H disappears; finally, when the proton is completely transferred, the situation again becomes "classical", with The contribution of the Bartlett, Perera and Del Bene's group to this topic is so significant that we have decided to divide this section in three parts: a) Other groups [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]; b) Bartlett-Perera-Del Bene [25][26][27][28][29][30][31][32][33][34][35][36]; c) Data analysis [37][38][39][40][41].…”

“…One dealing with 15 The last paper until now reports calculations of 3h J 15N-31P spin-spin coupling constants across N-H···O-P hydrogen bonded complexes [36]. This work is similar in subject but different in methodology to that of Czernek and Brüschweiler [12]. Instead of complex structures 9 and 10, Three-bond coupling constants can be appreciable when the phosphorous is P(V), but are negligible with P(III).…”

The Spin–Spin Coupling Constants in Ethane, Methanol and Methylamine: A Comparison of DFT, MCSCF and CCSD Results

“…Over the last decade, NMR shielding constants have been calculated routinely for a vast range of systems [5][6][7]. By contrast, ab initio calculations of spin-spin coupling constants in molecules containing more than 10-12 atoms have been carried out only recently [5,[8][9][10]. The reason for this difference lies in the failure of the simplest and least expensive ab initio method-the Hartree-Fock method-to provide spin-spin coupling constants with acceptable accuracy because of the instability or near-instability of this wave function to triplet perturbations as generated by the Fermi contact and spin-dipole operators [5].…”