Electronic coupling through-bond interaction

In the Forster mechanism, energy transfer occurs through dipolar interactions. This process is not coupled through bond interactions, and therefore orbital overlap and inter-component electronic coupling are unimportant. Dipole-dipole interactions may occur efficiently in systems where the donor and acceptor species are over 100 A apart, whereas Dexter energy transfer is typically efficient only up to distances of approximately 10 A. 

Interestingly, the sulfur-linked bis-crown ligand [8] shows an unprecedented cathodic potential shift upon addition of K+ cations to the electrochemical solution (Table 3). It is believed to be a conformational process that causes the anomalous shift of the ferrocene/ferrocenium redox couple and not a through-space or through-bond interaction, as these effects would produce the expected anodic potential shift of the ferrocene redox couple. The origin of the effect may be a redirection of the lone pairs of the sulfur donor atoms towards the iron centre upon complexation. This would increase the electron density... 

Since spin-spin coupling through bonds occurs because of the interaction between the magnetic moment of the atomic nucleus and the bonding electrons, the coupling constants reflect the bonding environments of the coupled nuclei. In H NMR... 

Through-bond interactions scalar (J) coupling via bonding electrons. 

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