The relationship between the bond length and the difference in proton affinities for the observation of heteronuclear low barrier hydrogen bonds

The formation of homonuclear LBHBs requires similar proton affinities (PA) for the bases linked, while a PA mismatch is observed in heteronuclear LBHBs. This mismatch compensates the inherent asymmetry in heteronuclear LBHBs and is therefore the standard case for heteronuclear LBHBs and not an exception from the rule.