Crystal formation of 1D coordination polymers based on chiral, achiral and racemic 1,2-cyclohexane scaffolds
Résumé
The enantiomerically pure ligands (1a, 1b) and the meso 1c based on the trans-1,2-cyclohexanediol and cis-1,2cyclohexanediol respectively were used for the formation of zigzag 1D coordination polymers, when combined with bent HgCl2. A racemic mixture or 1a/1b in 1/1 ratio has also been studied. Four 1D Coordination Polymers have been obtained and their structures have been analysed using X-Ray diffraction on single crystals and also on powder. 1a-HgCl2 (and isostructural 1b-HgCl2) crystallizes in the non-centrosymmetric P 212121 space group, 1c-HgCl2 in the non-centrosymmetric P 21212 space group and 1a0.51b0.5-HgCl2 crystallises in the centrosymmetric P 21/n space groups. The analysis of the network energies, evaluated on a partial charges calculation method (PACHA), used here for the first tim for a 1D coordination networks, allows to evaluate energetical parameters like the Packing Energy (PE) for each crystalline compound, as well as the cooperatitvity Index (CI), illustrating the influence of chirality on the packing for this series of 1D Coordination Polymers. It has been shown that the use of the achiral ligand 1c requires the highest cooperativity between the chains.
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