N-Methyl-2,2’-dipicolylamine domplexes as potential models for metal-mediated base pairs

Abstract

Metal-mediated base pairs can be used to insert metal ions
into nucleic acids at precisely defined positions. As structural data on the resulting metal-modified DNA are scarce, appropriate model complexes need to be synthesized and structurally characterized. Accordingly, the molecular structures of nine transition metal complexes of N-methyl-2,2’-dipicolylamine (dipic) are reported. In combination with an azole-containing artificial nucleoside, this tridentate ligand had recently been used to generate metal-mediated base pairs (Chem. Commun. 2011, 47, 11041–11043). The PdII and PtII complexes reported here confirm that the formation of planar complexes (as required for a metal-mediated base pair) comprising N-methyl-2,2’-dipicolylamine is possible. Two HgII complexes with differing stoichiometry indicate that a planar structure might also be formed with this metal ion, even though it is not favored. In the complex [Ag2(dipic)2](ClO4)2, the two AgI ions are located close to one another with an Ag···Ag distance of 2.9152(3) Å, suggesting the presence of a strong argentophilic interaction.