Coordination chemistry chiral structures

It should be emphasized that the extensive coordination chemistry known for tartaric acids refers almost exclusively to the chiral ligands. uieso-Tartaric acid is not a good complexing agent, most of the structural work done with this molecule being concerned with conformational studies of the acid189 and its salts. 

It is quite clear that knowledge obtained from the study of equilibrium states may be applied to mechanistic problems only in a very restricted sense. Nevertheless it is surprising that the choice of chiral auxiliary reagents for synthesis seems seldom to be influenced by considerations of structural coordination chemistry. It must be mentioned that such reactions are often carried out in a medium not familiar to the coordination chemist. ... 

The coordination chemistry of oxalate (ox, C2042-) compounds provides a series of very interesting compounds from the stereochemical and magnetic points of view [197]. Most frequently the compounds form honeycomb layers in the presence of transition metal ions, in which the stereochemistry of the metal ion coordination sphere alternates between A and A. However, a three-dimensional homochiral structure is also possible. On the other hand, the negative charge of the oxalates necessitates the incorporation of cations between them, which provides the opportunity to introduce chirality and additional functionality in materials. The compound formed between homochiral manganese II oxalate and iron II tris bipyridinc (bpy) with formula [Mn oxls]2 " [Fcn(bpy)3]2+ crystallises in the space group fJ4 32. 

It is fitting to begin this brief historical overview of chirality in organometallic and coordination chemistry with the name of Alfred Werner (1866-1919) who, as far back as 1893, applied van t Hoff and Le Bel s stereochemical ideas of the tetrahedral nature of the carbon atom to the structure of hexacoordinated metal complexes. He established their octahedral structure and predicted that some could exist in an enantiomeric form with the power of optical rotation. This prediction was followed in 1911 by the resolution of the two enantiomers of the complexes [Co (en)2(NH3)X]X2 (X = Cl, Br) (2.1)-X2 (en = ethylene diamine) (Figure 2.1). This overall work won him the Nobel Prize for Chemistry in 1913, following which he then went on to resolve the inorganic complex Co (OH)6[Co (NH3)4]3 Br6 (2.2)-Br6 (Figure 2.2). ... 

The construction of novel coordination polymers is a current interest in the field of supramolecular chemistry and crystal engineering, stemming from their potential applications as frinctional materials as well as their intriguing variety of architectures and molecular topologies. In particular, solid materials with either helical or chiral structures are of intense interest in chemistry and material science. Although solid materials with imusual structures are expected to increase in number, the exploration for preparing framework solids with chiral structures still remains a challenge. Thermal analysis is a fundamental tool for the characterization of these new coordination polymeric compounds. 

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