Synthesis and structure of functional spherosilicate building block molecules for materials synthesis

Cubic, trialkyl tin functionalized spherosilicates Si8O20(SnR3)8 (R = Me, nBu) and the pentagonal prismatic tin-spherosilicate Si10O25(SnMe3)10 have been synthesized and characterized. Single crystal X-ray structures were obtained for Si8O20(SnMe3)8 (I), Si8O20(SnMe3)8 · 4H2O (I · 4H2O), and Si10O25(SnMe3)10 · 4H2O (II). Structural metrics for the silicate cores observed in these structures were compared to other Si8O12 and Si10O25 cores reported in the CSD database. A pronounced tetragonal distortion of the Si8O20 cage leads to Si–O–Si bond angles that are considerably distorted in I · 4H2O when compared to other analogous Si8O12 structures described in the literature. These octameric stannylated spherosilicates readily react with metal chlorides to produce mesocopically interesting metal oxide and hybrid materials. An illustration of this is found in the reaction of the octameric anhydrous tin compound I with titanocene dichloride to give the octatitanocene derivative Si8O20(Cp2TiCl)8 · 3CH2Cl2 (III). The single crystal structure of III is also described.