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Enantiopure and racemic alanine as bridging ligands in Ca and Mn chain polymers
Author(s) -
Lamberts Kevin,
Möller Andreas,
Englert Ulli
Publication year - 2014
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520614021398
Subject(s) - enantiopure drug , alanine , bridging (networking) , polymer , chemistry , stereochemistry , enantioselective synthesis , organic chemistry , amino acid , biochemistry , computer science , catalysis , computer network
Under accelerated and controlled evaporation, chain polymers crystallize from aqueous solutions of Ca II and Mn II halides with enantiopure L‐alanine or racemic DL‐alanine. In all ten solids thus obtained zwitterionic amino acid ligands bridge neighbouring cations. The exclusively O‐donor‐based coordination sphere around the metal cations is completed by aqua ligands; the halides remain uncoordinated and act as counter‐anions for the cationic strands. Despite the differences in ionic radii and electronic structure between the main group and the transition metal cation, their derivatives with L‐alanine share a common structure type. In contrast, the solids derived from DL‐alanine differ and adopt structures depending on the metal cation and the halide. Homochiral chains of either chirality or heterochiral chains with different arrangements of crystallographic inversion centres along the polymer strands are encountered. On average, the six‐coordinated Ca II cations, devoid of any ligand field effect, show more pronounced deviation from idealized octahedral geometry than the d ‐block cation Mn II .