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 n itrogens) coordinates to Cu(II) as one strand of a short double helix. The crystal structure of the title complex, bis-(MePy3P)-dicopper(II) [Cu-2(MeP y3P)(2)], has been determined. The binuclear structure of [Cu-2(MePy3P)(2)] is in contrast to the monomeric Cu(II) complex [Cu(PY3P)] in which the lig and 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 [Cu-2(MePy3P)(2)] has now been added to the rapidly growing number of spont aneously forming helical assemblies, for which crystal structures have been determined. (C) 2001 Elsevier Science B.V. All rights reserved.