Background of the nuclear magnetic resonance antipodal shift induced by substituents; an analogy of the mesomeric effect with borane skeletons

Abstract

A range of substituents in those boranes or heteroboranes whose molecular structure is based on the icosahedron produce distinct n.m.r. chemical shifts at the cage atom antipodal to the point of substitution; such shifts can be correlated with the ¹³C chemical shift of the para-position in monosubstituted benzenes, and a parallelism, but not an identity, between ‘antipodal’ and ‘mesomeric’ effects is suggested.