Edge-sharing Octahedra

The crystal structure of [LiCaAlF,] contains LiF octahedra edge-shared with AIF octahedra, with fairly normal Li-F distances of 2.009 A. 

In rutile the metal atoms in a strand of edge-sharing octahedra are equidistant. In some dioxides, however, alternating short and long M-M distances occur, i.e. the metal atoms are shifted in pairs from the octahedron centers towards each other. This phenomenon occurs (though not always) when the metal atoms still have d electrons and thus can engage... 

In 2012, Liao and coworkers [52] reported a Dy6 octahedron (24, Figure 3.17), seen as two edge-sharing [(p4-0)Dy4] tetrahedra, with two tail-to-tail calixarene ligands. The ac susceptibilities show obvious temperature-dependent both in-phase (x ) and out-of-phase (x") signals under a zero dc field, indicating multiple relaxation SMM behaviour. 

The equatorial positions of the octahedron are occupied by the CN moieties of the [Ag(CN)2] groups. As in the pz derivative, each [Ag(CN)2] group connects two iron atoms defining the edges of a Fe4[Ag(CN)2]4 rhombus. However, the edge-shared rhombuses define 2D corrugated nets in contrast to the pz derivative, due to the three-coordination of the Ag atoms (see Fig. 19). A schematic view of one 3D network is depicted in Fig. 20. 

Nature of sites in crystal structure Vastly different, e.g., cube-octahedron octahedron-tetrahedron Similar, e.g., octahedra with slightly different bond lengths or ligands Identical, finite clusters, e.g., edge-shared octahedral dimers Identical, continuous chains, e.g., chains of edge-shared octahedra... 

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