Syntheses, Structures, and Reactions of 2,2,3,3-Tetrakis(trifluoromethanesulfonato)tetrasilanes: Hexacoordination ([4 + 2] Coordination) of the Two Central Silicon Atoms

The 2,2,3,3-tetrakis(trifluoromethanesulfonato)tetrasilanes RMe₂Si−Si(OTf)₂−Si(OTf)₂−SiMe₂R (OTf = OSO₂CF₃; 4a, R = Me; 4b, R = Et; 4c, R = t-Bu), a series of novel 2,2,3,3-tetrafunctionalized tetrasilanes, were synthesized by reaction of the respective 2,2,3,3-tetraphenyltetrasilanes 3a−3c with trifluoromethanesulfonic acid. The structural characterization of 4a−4c by single-crystal X-ray diffraction revealed a distorted octahedral coordination (distorted tetrahedral coordination, with the capping of two of the tetrahedral faces by oxygen atoms opposite short Si−O bonds) of the two central silicon atoms due to Si···O interactions with one oxygen atom of each of the two trifluoromethanesulfonato groups on the adjacent silicon atom. As demonstrated by the reaction of 4a with methylmagnesium chloride, acetyl chloride, and 2-propanol, the title compounds can serve as versatile starting materials for the synthesis of other 2,2,3,3-functionalized tetrasilanes.