The structural chemistry of As, Sb, and Bi

Total number of electron pairs Bond type Lone pairs Bond arrangement Proved for 

The bond arrangements of Table 20.1 have been established by structural studies of simple ions or covalent molecules for the elements indicated. The presence of a lone pair implies M otherwise M. The paucity of information about Bi is due to the more metallic character of this element, which does not form many of the simple covalent molecules formed by As and Sb. The octahedral bonds formed by Bi in, for example, the crystalline pentafluoride have considerable ionic character. For 7-coordination (sp d ) a pentagonal bipyramidal bond arrangement would be expected. We noted in Chapter 7 that SbBtg should form a distorted octahedron since there is a valence group of 14 electrons including one lone pair. In fact the ion shows very little distortion from a regular octahedron, (see p. 706). 

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