Tris [(trimethylsilyl)oxy] antimony

Tris[(trimethylsilyl)oxy]antimony (Sb(OSiMe₃)₃, 1) has been prepared from SbCl₃ and 3 equiv. of LiOSiMe₃ in diethylether. According to mass spectrometric and NMR spectroscopic data, 1 appears to be a monomer in solution and in the gas phase. Dimerisation occurs, however, in the solid state as verified by an X-ray crystal structure determination. The unit cell contains three crystallographically independent monomers, two of which form one type of dimer, while the other is part of a centrosymmetrical dimer. In both types of dimers two Sb atoms are connected via two OSiMe₃ groups to form distorted Sb₂O₂-squares. Together with the remaining 4 OSiMe₃ groups and the two stereochemically active lone pairs, each Sb exhibits a trigonal bipyramidal coordination.