Spin coupling constants reduced

The reduced indirect (scalar) nuclear spin-spin coupling constant Kkl describes the interaction of the magnetic nuclei, transmitted through the surrounding electrons. Kkl is four orders of magnitude smaller than DK. 

In experimental practice the isotropic NMR shielding constant a is replaced by the NMR chemical shift 8 and the spin-spin coupling constant JKL is used instead of the reduced spin-spin coupling constant Kkl. 

Table 8 Reduced one-bond metal-ligand spin-spin coupling constants for some transition metal complexes, in 1019T2J 1. DFT computations (BP non-hybrid functional) employing all-electron Slater-type basis sets for the 3d metal M-C and M-0 couplings, Slater-type frozen-core basis sets for the metals in all other cases. Data taken from Khandogin Ziegler, Ref. 119...

Fig. 7 One-bond metal-ligand reduced nudear spin-spin coupling constants (absolute values) for 5d metal complexes. Scalar relativistic ZORA DFT results (VWN functional) versus experimental values. A few data points for Pb are also included. Data taken from Refs. [45,123]. The line is not a fit but indicates where Ka c = Kexp. The different markers indicate the different metals. For not octahedrally or not tetrahedrally coordinated metal centers, the first coordination shell was completed with solvent molecules, as described in Ref. [124]...

The C chemical shifts and some selected C- H spin coupling constants of compound 73 and its hydrochloride are collected in Table 48. The data show a high degree of consistency - in nearly all cases the chemical shifts for carbons of the amino alcohol chain (carbons C-H) are somewhat reduced when switching from the free bases to the hydrochloride salts (the opposite trend is observed for the corresponding H chemical shifts) <2001MOL796>. 

The nuclear spin-spin coupling constant, "/(A-B) is a measure of the energy of interaction between the magnetic moments of nuclei A and B. The interaction is transmitted by a magnetic polarization of the electrons in the molecule and J is therefore an intrinsic second-order property of the molecule, depending in a subtle manner on the details of the electron distribution. It is often convenient to define a reduced spin-spin coupling constant, "K(A-B), independent of the magnetic moments of A and B... 

Autschbach and Ziegler performed the relativistic calculations of spin-spin coupling constants (isotropic part) and anisotropies in heavy atom compounds with the two-component zeroth-order regular approximation (ZORA) method. The experimentally determined reduced spin-spin coupling tensor elements Kjk A,B) between two magnetically active nuclei, A and... 

Since the short relaxation times associated with a quadrupolar nucleus drastically reduce the time delay to be applied in an NMR experiment between two pulses, measuring times are short or, in other words, distinct NMR signals can often be detected with a limited time spent down to micromolar concentrations. Along with this apparent advantage, quadrupolar nuclei provide information in addition to the classical parameters chemical shift (or shielding) and nuclear spin-spin coupling constants. Variations in linewidths for quadrupolar nuclei are another sensitive quantity allowing for the evaluation of the electronic and the steric situation in the first coordination sphere of a vanadium compound, its periphery, its (local) symmetry and its interaction with the matrix, i.e. counter-ions, solvent molecules and other constituents present in solution. 

Earlier correlations, relating the magnitude of the spin-spin coupling constant /p-N-p to the properties of the phosphorus substituents in cyclotri-phosphazenes, have been extended to include a wider range of endo- and exo-cyclic substituents. When carbon replaces phosphorus in rings of the type (25), /p-N-p is reduced by a constant factor for a given substituent, and it was... 

The reduced coupling tensor KMNuv is independent of the magnetogyric ratios 7M and yN (which could be positive or negative) and depends on the electronic structure of the system only. In many cases the orientationally averaged value of the nuclear spin-spin coupling tensor Jmnuv (the nuclear spin-spin coupling constant JMn)... 

The reduced spin-spin coupling constant may now be calculated as... 

An analytical perturbation theory of the Fermi-contact contributions to reduced spin-spin coupling constants has been extended to planar trigonal and tetrahedral main group element fluorides and to octahedral fluorides. ... 

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