Electron Transfer in Weak Outer Complexes B- XY

We assume that, on formation of B- XY, a fraction (i = intermolecular) of an electronic charge is transferred from the electron donor atom of Z of the Lewis base B to the pz orbital of X and that similarly a fraction 5p (p = polarisation) of an electronic charge is transferred from pz of X to pz of Y, where z is the XY internuclear axis and n and n are the valence-shell principal quantum numbers of X and Y. Within the approximations of the Townes-Dailey model [187], the nuclear quadrupole coupling constants at X and Y in the hypothetical equilibrium state of B- -XY can be shown [178] to be given by  

The values of 3p also behave systematically, as shown in Fig. 21, in which 5p is plotted against ka for the various series B- XY. It is evident that, for a given XY, 3p is an approximately linear fimction of ka and hence of the strength of the interaction. Moreover, for a given B the order of 5p is ICl BrCl Br2 CI2, which is the order of the polarisabUities of the leading atoms X in B- XY and therefore seems reasonable from the definition (see earlier) of 3p. 

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