Enantioselective Synthesis or Resolution of Chiral Ligands

1 Single-molecule Magnets and Chains (ID Molecular Magnets) 

In a cluster, the large number of magnetic centres located in a small volume produces magnetic properties. Metallocrowns (MCs) can provide clusters that possess transition 

Combining hexacyanoferrate (III) anions with Ni(II) complexes derived from the enantiopure ligands trans-(lS, 2S)- or trans-(i/, 2/ )-cyclohexane-1,2-diamine (6.78) (chxn), Coronado obtained enantiopure layered ferromagnets T = 13.8K). The compounds [Ni(frani-(i5,25)-chxn)2]3[Fe(CN)5].2H20 (i5,25)-(6.79) and [Ni(frani-(IR, 2/ )-chxn)2]3[Fe(CN)6].2H20 IR, 2R)- 6.19) crystallize in the PI space group. 

CD measurements of the (IS, 25)-(6.79) isomer exhibit positive Cotton effects at 450 nm and 725 nm and a negative one at 585 nm, the IR, 2P)-(6.79) isomer exhibiting effects of opposite sign. In contrast, the racemic diamine ligand leads to a centrosymmetric structure belonging to the P-1 space group. 

Crystal packing of (R)-(6.77) (above) and (rac)-(6.76) (below) (reproduced with permission from referencecopyright 2003, Elsevier). 

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