On the role of mercury in the non-covalent stabilisation of consecutive U–HgII–U metal-mediated nucleic acid base pairs: metallophilic attraction enters the world of nucleic acids

Abstract

Metal atoms with a closed-shell electronic structure and positive charge as for example the Au^I, Pt^II, Ag^I, Tl^I or Hg^II atoms do not in some compounds repel each other due to the so-called metallophilic attraction (P. Pyykkö, Chem. Rev., 1997, 97, 597–636). Here we highlight the role of the Hg^II⋯Hg^II metallophilic attraction between the consecutive metal-mediated mismatched base pairs of nucleic acids. Usually, the base stacking dominates the non-covalent interactions between steps of native nucleic acids. In the presence of metal-mediated base pairs these non-covalent interactions are enriched by the metal–base interactions and the metallophilic attraction. The two interactions arising due to the metal linkage of the mismatches were found in this study to have a stabilizing effect on nucleic acid structure. The calculated data are consistent with recent experimental observations. The stabilization due to the metallophilic attraction seems to be a generally important concept for the nucleic acids containing heavy metals with short contacts.