The oxyhalides of trivalent Sb

Structural data are available for only one oxyfluoride. Four forms of SbOF have been prepared thermally from SbF3 and Sb203. In one form the coordination group around Sb consists of 2 0 and 2 F at four of the vertices of a trigonal 

The structures of complex bismuth oxyhalides. (a) Metal-oxygen sheet viewed in directions parallel and perpendicular to the sheet, (b), (c), (d) Elevations of structures built from (b) single halogen layers Xj, (c) double halogen layers Xj, and (d) triple halogen layers 

Other oxyhalides, mostly oxychlorides and oxybromides, result from the controlled hydrolysis of the trihalides, and are of interest for two main reasons. First, they are quite unrelated to the oxyhalides of bismuth. Although both antimony and bismuth form compounds MOX the structures of the antimony compounds are quite different from those of the compounds BiOX, which have been described on p. 408. The more complex oxyhalides of Sb have no analogues among Bi compounds. Second, a feature of the published structures of the antimony oxyhalides is the coordination of Sb by either three or four O atoms. It should perhaps be remarked here that the investigation of the structures of these complex compounds is difficult, and the precise positions of the O atoms are by no means certain. However, it appears that a feature of these compounds is the formation of extended Sb—O systems, generally layers, interleaved with halogen 

SbOCl is built of puckered sheets in which two-thirds of the Sb atoms are linked to 2 0 + 1 Cl and the remainder to 4 0, the sheets (SbgOgC ) being held together by Cl ions. (The distinction between the two types of Cl is based on the much greater Sb—Cl distance (2-9 A) between Sb and interlayer Cl than Sb—Cl within a layer (2-3-2-5 A). 

Sb40sCl2. Again there are infinite layer ions, here of composition (Sb40s)S , in which one half of the Sb atoms are 3- and the others 4-coordinated, with Cl ions between the layers. 

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