Chiral monomeric and homochiral dimeric copper(II) complexes of a new chiral ligand, N-(1,2-bis(2-pyridyl)ethyl)pyridine-2-carboxamide:: An example of molecular self-recognition

Reaction of Cu(ClO4)(2)(.)6H(2)O with a racemic mixture of the novel chiral ligand N-(1 2-bis(2-pyridyl) ethylpyridine-2-carboxamide (PEAH) affords only the homochiral dimeric copper(II) complexes [Cu-2((R)PEA)(2)](ClO4)(2) and [Cu-2((S)PEA)(2)]-(ClO4)(2) in a 1:1 ratio. The phenomenon of molecular self-recognition is also observed when a racemic mixture of the monomeric copper(II) complex [Cu((R(S))PEA)(Cl)(H2O)] is converted into the homochiral dimeric species [Cu-2((R(S))PEA)(2)](ClO4)(2) via reaction with Ag+ ion. This is the first report of direct conversion of a racemic mixture of a chiral monomeric copper(II) complex to a mixture of the homochiral dimers.