Orthogonal multipolar interactions

Paulini, R., Muller, K. and Diederich, F. (2005) Orthogonal multipolar interactions in structure chemistry and biology. Angew. Chem. Int. Ed., 44, 1788-1805. 

Molecules composed of atoms of different electronegativities have usually an asymmetric distribution of electrons, which produces electronic dipoles. These dipoles within a cell or in aqueous medium can be attracted by a close-by ion, establishing so-called charge-dipole interactions. A permanent dipole can also interact with another permanent dipole leading to a dipole-dipole interaction. In a recent review, Diederich et al. has listed these orthogonal multipolar interactions among which C—X C=0 (X=halogen),... 

Paulini et al. introduced the term orthogonal multipolar interactions to describe situations that were not previously recognized (05AG(IE)1788). Among these interactions, there is one relevant for the present work, that present between the o-nitro substituent on the 1-aryl ring and the N2 atom of an azole. 

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