Antimony homocycles

The lability of the E-E and E-C bonds in cyclostibines and cyclobismuthines is readily evident in reactions of these homocycles with metal carbonyls. Under mild conditions, complexes in which the antimony ligand acts as a two-electron donor towards the metal centres may be isolated, e.g. cyclo-( BuSb)4[W(CO)5] (n=l,2) cf. metal complexes of cyclophosphines, see Section 7.1.1). In boiling solvents, however, rupture of the inorganic homocycle and/or the E-C bonds... 

General names for systems of rings or chains are composed of the name of the substituent and the element. For example, the name methylarsenic refers to all the systems of the type (MeAs) . The progress in the field of organoarsenic or organoanti-mony " mono-and polycycles has been summarized several times in excellent reviews. In this survey stress is laid on recent developments mainly in the field of cyclostibanes, and an attempt is made to compare analogous homocycles of arsenic and antimony. 

Relatively little is known of the chemistry of antimony rings compared to arsenic rings. The reactions of arsenic homocycles have been reviewed several times " . They include cleavage of the As—As bonds with halogens and insertion of chalcogens or unsaturated hydrocarbons and reductive cleavage with potassium metal. Representative examples are given in equations 15-18. 

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