Chirality in coordination polymers: homo- vs. hetero-chiral strand construction

The functionalised cage amine complex, [1,8-bis(carboxymethylamino) sarcoph agine] cobalt() (sarcophagine = 3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosan e), serves as a chiral supramolecular synthon in the formation of coordinat ion polymers in which various metal(III) ions form labile links in the poly mer strands. Both amorphous and crystalline polymers form, depending, among st other factors, upon the stereochemistry at Co(III) and the nature of the metal(II) species. In the cases of Co, Ni, Cu and Zn as the linker species , polymers of 1 : 1 Co : M stoichiometry are obtained, whereas Mn is found to give both Co/Mn and Co/Mn-2 'monomer' units. Crystal structure determina tions are reported for the Co/Mn, Co/Mn-2, Co/Co and Co/Zn systems.