Crystal structure of a chiral Ni complex: (R,R)-N,N'-bis(3-t-butylsalicylidene)-1,2-cyclohexanediaminonickel(II).

properly furnished, metal complexes from salen ligands can recognize neutral molecules, 1 and extract alkaline metal ions 2 as well as cations and anions 3 in addition to possessing catalytic properties. The interaction between central metal ions and substrates is much controlled by peripheral groups of ligands. In order to establish design criteria for more effective salen complexes, we prepared a series of chiral salen metal complexes for structure-property evaluations. The title complex (Fig. 1) possesses t-butyl groups at the 3,3′-positions and has excellent solubility in most common organic solvents, such as THF, chloroform, and acetone, because of them. The presence of these t-butyl groups also provides a significant steric effect, which is important in controlling the selectivity. The chiral complex was obtained by the treatment of Ni(OAc)2 with a chiral ligand,