Fixed helical Cd(II) coordination polymers assembled from diastereopure Schiff-base ligands derived from condensation of acetylacetone with 1S,2S- and 1R,2R-cyclohexanediamine

The 1:1 interaction of the diastereopure Schiff bases (1S,2S)-bis(acetylacetone)-cyclohexanediimine (L1) and (1R,2R)-bis(acetylacetone)cyclohexanediimine (L2) with CdI2 yields the new helical metal coordination polymers [CdL1I2]n (1) and [CdL2I2]n (2). The respective X-ray structures, as expected, confirmed 1 and 2 to be enantiomeric, existing as right-handed (P) and left-handed (M) helical chains in which both L1 and L2 are formally present in their (unusual) uncharged ketoamine form, with the (protonated) amine nitrogens not coordinated. The Cd(II) centres in 1 and 2 display distorted tetrahedral coordination geometries being bound to two iodo ligands and two oxygen donor atoms from individual ketoamine domains belonging to different Schiff base ligands.