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Total Spontaneous Resolution of Chiral Covalent Networks from Stereochemically Labile Metal Complexes
Author(s) -
Johansson Anna,
Håkansson Mikael,
Jagner Susan
Publication year - 2005
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200500094
Subject(s) - enantiopure drug , enantiomer , chemistry , covalent bond , zinc , metal , chiral ligand , stereochemistry , crystallography , copper , chiral resolution , valence (chemistry) , racemic mixture , enantioselective synthesis , organic chemistry , catalysis
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)] ∞ crystallises as a conglomerate and yields either enantiopure ( R , R )‐ 1 or enantiopure ( S , S )‐ 1 . A mixed‐valence copper( I / II ) complex, [{Cu II Br 2 (dmeda)} 3 (Cu I Br) 2 ] ∞ ( 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 handedness. 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 enantiomeric excess of the bulk product can be undertaken by means of solid‐state CD spectroscopy.