Organoantimony homocycles

TABLE 9. Colours and structural data of some associated organoantimony homocycles... 

This observation sheds some light on the question as to why pentamers are formed with n-alkyl substituents but hexamers with slim aryl substituents. A possible explanation, at least for the organoantimony homocycles, is that in solution jjentamers dominate both with alkyl and aryl substituents. In the solid state, however, the six-membered form allows a closer packing of the phenylantimony rings than the pentameric form. 

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