Lanthanide halides cluster complexes

The synthesis of compounds of the lanthanides containing cluster complexes follows in general the same routes as described in The Divalent State in Solid Rare Earth Metal Halides, the conproportionation route and the metallothermic reduction route, for example... 

Additional areas of lanthanide halide chemistry that have been reviewed include the synthesis, phase studies, and structures of complex lanthanide halides - compounds formed between one or more group 1 cation and lanthanide element halides (Meyer 1982). Halides in combination with lanthanide elements in the II, III, and IV oxidation states were considered with the chemistry of the heavier halides being emphasized. More recently the reduced ternary lanthanide halides (Meyer 1983) and the reduced halides of the lanthanide elements were reviewed (Meyer 1988). The latter review considered lanthanides in which the formal oxidation state of the cation was 2 and included hydride halides, oxide halides, mixed-valence ternary halides, and reduced halide clusters. Corbett et al. (1987) discussed the structures and some bonding aspects of highly reduced lanthanide halides and compounds stabilized by a second-period element bound within each cluster, e.g., SC7CIJ2B, SC5CI5B, YjCljC. 

Oxide-halides of the alkaline-earth-hke divalent lanthanides, OlGlXe (R = Eu, Yb, Sm) are discussed in The Divalent State in Solid Rare Earth Metal Halides. Although, these have the topology of cluster complexes with isolated... 

Related complexes are obtained with Pd, where one face of a benzene ring is shared by two Pd atoms . Mono-f/ -benzene ligands on a pentacobalt cluster also form from the aluminum halide-aluminum metal conditions . The preparation of -arene complexes of the lanthanides and actinides has been more diflScult, presumably because of the proclivity of these metals to form ionic bonds. Reactions between hexamethylbenzene and metal halides in the presence of AlClj-Al or AlCl-Zn reagents in the isolation of a mononuclear Sm complex, in addition to di- and trinuclear U complexes. ... 

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