Untersuchung der indirekten Kernspinkopplung zwischen Protonen und Kohlenstoff-13 über mehrere Bindungen

By an exact analysis of higher-order-spectra, or by double resonance experiments, the signs and magnitudes of the indirect spin-spin coupling between H¹ and C¹³ separated by two or three bonds are measured in a variety of compounds. Since the sign is measured relative to those of the one bond CH-coupling it is shown that in CH₃X compounds where X is any of the first row elements these are as expected from a maximum overlap calculation. For the geminal CCH-coupling in ethanelike fragments a correlation is established with the one-bond CH-coupling. A theoretical interpretation is given which uses a VB-formulation based on the Dirac-Vector-model and gives satisfactory agreement with experiment.