Donor-acceptor interaction arrow-pushing

Following the procedure for vicinal interactions illustrated in Example 1.4 and Section 3.3.1, we can associate each geminal ctab— obc donor-acceptor interaction with an arrow-pushing diagram and partial admixture of an alternative resonance diagram, as shown in Fig. 3.78. The formal two-electron transfer from gab to obc results in the NBO configuration... 

Figure 3.78 Generic arrow-pushing diagrams (left) and secondary resonance structures (right) for vicinal (upper) and geminal (lower) NBO donor-acceptor interactions.

Figure 9.1 Generic arrow pushing diagram (left) and secondary resonance structure (right) for intermolecular NBO donor-acceptor interaction (cf. Fig. 5.6).

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