Structural chemistry oxyhalides

Systematic features in the structural chemistry of the uranium halides, oxyhalides and related transition metal and lanthanide halides, J. C. Taylor, Coord. Chem. Rev., 1976, 20,197-273 (205). 

The last three chapters summarize unique structural and chemical features of a variety of glasses. They also provide an overview of the important aspects of the glass systems. Chapters 12 and 13 discuss respectively oxide and chalcogenide glasses particularly in view of their chemistry, structure and a number of special phenomena associated with them. In chapter 14, synthesis, structure and properties of halide, oxyhalide, oxynitride and metallic glasses are discussed. Some aspects of glass-like carbon have also been presented. 

Current interest in metal cluster compounds has arisen from the demonstration that metal-metal bonds play a key role in determining the chemistry of large classes of compounds, in particular, those with heavy metal atoms in low valent states. The occurrence of metal-metal bonding in transition metal complexes has been surveyed 21, 26, 59, 271, 275), and the criteria for metal-metal bonding and the factors contributing to the stability of such bonds have been discussed. Schafer and Schnering Sll) and more recently Keppert and Vrieze 229) have reviewed the lower halide, oxide, and oxyhalide clusters of the heavier transition metals. Cotton 102) has considered the transition metal clusters in terms of structural types, and a similar approach has been adopted in a review of molecular polyhedra of high coordination number 309). 

The FeOCl-type oxyhalides can be intercalated by lithium and various molecules. Molecular intercalates of FeOCl and AlOCl (which has a different layer structure) were in fact obtained before those of dichalcogenides . However, the chemistry of lamellar oxyhalides is distinguished from that of lamellar dichalcogenides by a substitution reaction in which the outer layers of the slabs (i.e., the chlorine layers) are easily replaced by other ion layers such as OH", [NH2]". The structure thus lends itself not only to reversible topochemical reactions by intercalation, but also to irreversible topochemical... 

The different families of compounds based on these discrete units so far obtained in solid-state chemistry are reported, with their crystal structures, in Table 1. Relevant examples are included of all the possible combinations of mono-, di-, and trivalent countercations, giving VEC of 16 and 15, that have been obtained. In contrast, compounds with VEC of 14 appear only in one oxyhalide series as stated above. 

Pershina, V., Sepp, W.-D., Bastug, T., Fricke, B., and Ionova, G. V. 1992. Relativistic effects in physics and chemistry of element 105. III. Electronic structure of hahnium oxyhalides as analogs of group 5 elements oxyhalides, J Chem Phys 97, 1123-1131. 

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