Structure and Enantio-DifferentiatingBehaviors of Nickel(II)Complexes with Chiral Schiff Base Ligands Derived from 1,1'-Binaphthyl-2,2'-diamine

摘要

Crystal structures of nickel(II), copper(II), and palladium(II) complexes with (R)-/(S)-2,2'-bis(salicylideneamino)- 1,l'-binaphthyl were determined. The nickel complex 1 is binuclear' consisting "of twoNi~(2+) ions 'and homochiral two ligand dianions in the crystal. Each Nit+ ion has a trans-N202 square-planar coordination sphere. Either the metal ion or the ligand is less distorted in brnuclear complex' 1 as'eompared with the mononuclear copper(l[) complex, which has an intermediate structure between square-planar and tetrahedral forms: When dissolved in solvent, complex 'Idissociates into mononuclear species. It is likely that crystallization involves partial ligand-exchange of a mononuclear complex with another molecule of the same chirality to form a homochiral dimer in a self-sorting fashion. Nickel compiex with 2,2'-bis(4-methoxysalicylideneamino)-1,1'-binaphthyl (2) forms a 1:1 adduct whh (R)2-(l-hydгoxye thylpyгidiпe in chloroform solution. The binding constant of (R)-2 is twofold higher than that of (S)-2, which means that the adduct formation proceeds with enantio-differentiation.