Organoantimony(V) Oxido Cubane Cluster [(p-X-C₆H₄Sb)₄(O)₄(Ph₂SiO₂)₄] (X = Cl, Br) Stabilized by Diphenyldisiloxides

Reaction of (p-halophenyl)stibonic acid with diphenylsilanediol (in ratio 1:1) in refluxing toluene for 6 h afforded colorless crystalline products in high yields. Single-crystal X-ray structural elucidation reveals the formation of the products [(p-Cl-C₆H₄Sb)₄(O)₄(Ph₂SiO₂)₄] (1) and [(p-Br-C₆H₄Sb)₄(O)₄(Ph₂SiO₂)₄] (2), respectively. The clusters 1 and 2 were isostructural; the core consists of a distorted Sb₄O₄ cubane framework with the siloxides acting as bridging ligands across the antimony atoms present at alternate corners of the cube.