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In catena-poly[copper(II)-di-μ-chlorido-μ-proline-κ2 O: O′], [CuCl2(C5H9NO2)] n, two symmetry-independent metal cations adopt distorted octahedral coordination, typical for d9 Jahn-Teller systems. Each chloride bridge is involved in both a short and a very long interaction with a CuII centre. The centrosymmetric crystal structure contains homochiral chains of opposite handedness which extend along the shortest lattice parameter ( i.e. a). The O: O′-bridging coordination mode of proline, although a common motif for such complexes in general, is remarkable for CuII; the vast majority of amino acid derivatives of this cation are characterized by N, O-chelation. [ABSTRACT FROM AUTHOR]

Reactions of calcium bromide with enantiopure and racemic proline in aqueous solution lead to two solids in which the zwitterionic amino acid acts as a bridging ligand between neighbouring cations. Depending on the chirality of the amino acid, topologically very different products are obtained. With racemic proline, bromide acts as a simple uncoordinated counter-anion for the cationic heterochiral chains in catena-poly[[aquacalcium(II)]-μ-aqua-μ3-DL-proline-μ2-DL-proline], {[Ca(C5H9NO2)2(H2O)2]Br2} n. In agreement with chemical intuition, only carboxylate and aqua O atoms coordinate the alkaline earth cation in a low-symmetry arrangement. In contrast, L-proline affords the two-dimensional network poly[dibromidobis(μ2-L-proline)calcium(II)], [CaBr2(C5H9NO2)2] n, with an unexpected CaBr2 unit in a more regular coordination sphere. [ABSTRACT FROM AUTHOR]

In catena-poly[copper(II)-di-μ-chlorido-μ-proline-κ2 O: O′], [CuCl2(C5H9NO2)] n, two symmetry-independent metal cations adopt distorted octahedral coordination, typical for d9 Jahn-Teller systems. Each chloride bridge is involved in both a short and a very long interaction with a CuII centre. The centrosymmetric crystal structure contains homochiral chains of opposite handedness which extend along the shortest lattice parameter ( i.e. a). The O: O′-bridging coordination mode of proline, although a common motif for such complexes in general, is remarkable for CuII; the vast majority of amino acid derivatives of this cation are characterized by N, O-chelation. [ABSTRACT FROM AUTHOR]