Halogenocuprate coordination number

On the Coordination Number of the Metal Crystalline Halogenocuprates(I) and Halogenoargentates(I)... 

ON THE COORDINATION NUMBER OF THE METAL IN CRYSTALLINE HALOGENOCUPRATES(I) AND HALOGENOARGENTATES(I)... 

In the following presentation, solid-state structures documented hitherto for halogenocuprate(I) and halogenoargentate(I) ions are described in order of increasing coordination number of the metal, Possible correlations between the coordination number of copper(I) or silver(I) in the anion and properties of the cation with which it is coprecipitated, such as size, shape, and exposure of the positive charge, are then discussed. 

A metal coordination number of four is undoubtedly that most commonly exhibited in halogenocuprates(I) and halogenoargentates(I), vertex, edge, and face sharing of metal(I)-ligand tetrahedra leading to a wealth of structural motifs, especially where polymeric anions are concerned. 

Extreme diversity is exhibited in the coupling of metal halide tetra-hedra to form polymeric halogenocuprate(I) and halogenoargentate(I) ions, there being an abundance of different types of infinite chains, layers, and three-dimensional arrays. Because the object of this article is to focus on variations in metal coordination number, and, in particular, on trends associated with the nature of the cation, structural description will be limited to those types of polymeric anion most frequently encountered hitherto in crystalline halogenocuprates(I) and halogenoargentates(I). 

Fig. 15. The copper(I) coordination number as a function of the concentration of the halogenide ligand (mol dm-3) in halogenocuprates(I) crystallizing with symmetrically substituted quaternary ammonium, phosphonium, and arsonium cations.

That there is a relationship between the coordination number of the metal in crystalline halogenocuprates(I) and halogenoargentates(I) and the properties of the cation with which it is coprecipitated would now seem to be well established. The tuning of anionic configurations to cation properties reflects the versatility in coordination requirements not only of the metal but also of the ligands. Cation size would appear to be of prime importance for the determination of a particular metal(I) coordination number, the tendency to attainment of a higher coordina-... 

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