Bis-(N,N′-bis[2-(2-pyridyl)methyl]pyridine-2,6-dicarboxamido)dicopper(II): spontaneous formation of a short double stranded helicate

In its deprotonated form, the ligand N,N′-bis[2-(2-pyridyl)methyl]pyridine-2,6-dicarboxamide (MePy3PH2, where the Hs represent the dissociable amide nitrogens) coordinates to Cu(II) as one strand of a short double helix. The crystal structure of the title complex, bis-(MePy3P)dicopper(II) [Cu2(MePy3P)2], has been determined. The binuclear structure of [Cu2(MePy3P)2] is in contrast to the monomeric Cu(II) complex [Cu(Py3P)] in which the ligand N,N′-bis[2-(2-pyridyl)ethyl]pyridine-2,6-dicarboxamide (Py3PH2) differs from MePy3PH2 by only a single methylene linker. The helical structure of [Cu2(MePy3P)2] has now been added to the rapidly growing number of spontaneously forming helical assemblies, for which crystal structures have been determined.