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Total Spontaneous Resolution (total + spontaneous_resolution)
Selected AbstractsTotal Spontaneous Resolution of Five-Coordinate Complexes,ANGEWANDTE CHEMIE, Issue 32 2009Anders Lennartson Sauber getrennt: Mithilfe von Zink- und Cadmiumdiethyldithiocarbamaten gelang erstmals die Racematspaltung bei größeren Mengen an fünffach koordinierten Komplexen. Das stereochemische Ergebnis lässt sich durch Zugabe des gewünschten Isomers beeinflussen, was einen praktischen Zugang zu jedem Enantiomer mit hohem Enantiomerenüberschuss und hoher Ausbeute eröffnet. [source] Total Spontaneous Resolution of Chiral Covalent Networks from Stereochemically Labile Metal ComplexesCHEMISTRY - A EUROPEAN JOURNAL, Issue 18 2005Anna Johansson Abstract 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(NO3)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, [{CuIIBr2(dmeda)}3(CuIBr)2], (2), which crystallises as a pair of interpenetrating chiral (10,3)- a nets, is formed from CuBr, CuBr2 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[ZnCl4] (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. [source] | ||||||||||