Hydrogen bonding and halogen–halogen interactions in 4-halopyridinium halides

Abstract

The solid state structures of the 4-halopyridinium halides 4-XC₅H₄NH⁺X^- (X=Cl, Br, I) all display chains of the form [···X–C₅H₄N–H⁺···X^-···X–C₅H₄N–H⁺···X^-···] involving N–H···X^- hydrogen bonds and X···X^- contacts; the former become longer and the latter shorter (relative to the sum of the van der Waals radii) with increasing size of X.