Siloxanes, chloro derivatives

The first structural report of an alumo-poly siloxane appeared as early as 1966 the molecule (Me2SiO)4(OAlBr2)2(AlBr) has an Si4Al2Ofi 12-membered cycle which is spirocyclically bridged by an Al-Br unit (see Fig. 3).68 Only in 2000 was the corresponding structure of the chloro-derivative (which is iso-typic to the bromo-compond) published.69 In both compounds, all silicon and aluminum atoms are tetra-coordinate with the exception of the spiro-cyclic central bromo(chloro)-aluminum -moiety, which is penta-coordinate with four oxygen bonds. 

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