Zur theoretischen Interpretation von NMR-chemischen Verschiebungen tetrakoordinierter zentralatome. IV—CNDO/2-Berechnungen von 29Si-NMR-chemischen Verschiebungen. Der Einfluß der ΔE-Näherung

On the basis of the CNDO/2 method paramagnetic screening constants of the central atom of tetrasubstituted silicon compounds of the type Me_4–nSiX_n (X = F, OMe, NMe₂, C1) are calculated, both with and without ΔE approximation. The results are compared with the experimental ²⁹Si n.m.r. chemical shifts. The ‘averaged excitation energies’ ΔE obtained from the comparison of calculated values depend on the charge of the central atom and cannot be considered to be constant for quantitative studies.