Total Spontaneous Resolution of Chiral Covalent Networks from Stereochemically Labile Metal Complexes

摘要

Stereochemically labile copper and zinc complexes with the N,N'-dimethylethylenediamine ligand(dmeda)have been shown to be promising precursors for the total spontaneous resolution of chiral covalent networks.(N,N')-[Cu(NO_3)_2(dmeda)]_(infinity)crystallises as a conglomerate and yields either enantiopure(R,R)-1 or enantiopure(S,S)-1.A mixed-valence copper(I/II)complex,[{Cu~IIBr_2-(dmeda)}_3(Cu~IBr)_2]_(infinity)(2),which crystallises as a pair of interpenetrating chiral(10,3)-a nets,is formed from CuBr,CuBr_2 and dmeda.One net contains ligands with solely(R,R)configuration and exhibits helices with(P)configuration while the other has solely(S,S)-dmeda ligands and gives rise to a net in which the helices have(M)configuration.The whole crystalline arrangement is racemic,because the interpenetrating chiral nets are of opposite hand-edness.With zinc chloride(R,S)-[ZnCl-(dmeda)_2]_2[ZnCl_4](3)is obtained,which is a network structure,although not chiral.Total spontaneous resolution of Stereochemically labile metal complexes formed from achiral or racemic building blocks is suggested as a viable route for the preparation of covalent chiral networks.Once the absolute structure of the compound has been determined by X-ray crystallography,a quantitative determination of the enan-tiomeric excess of the bulk product can be undertaken by means of solid-state CD spectroscopy.