Group 4 Metallocene and Half-sandwich Derivatives of Spherosilicate: Preparation fromSi8O20(SnMe3)8 and Their Olefin Polymerization Activity

Three metallocene and half-sandwich Group 4 complexes of cuboctameric

spherosilicate (Si8O20(TiCp2Cl)8, Si8O20(ZrCp2Cl)8, and Si8O20(TiCp*Cl2)8) were successfully prepared by the exchange reaction of Group 4 metal chlorides with the spherosilicate starting material, Si8O20(SnMe3)8. These complexes were found to be catalytically active in olefin polymerization. Their preparative reactions clearly demonstrate a synthetically useful route towards many other derivatives of spherosilicate through the Si8O20(SnMe3)8 starting material. A new synthesis of the key precursor, octa(trimethyltin) cuboctameric spherosilicate Si8O20(SnMe3)8, was developed. It was found that most of the waters of hydration of the initial hydrate ([NMe4][Si8O20] @ n H2O, = 60! 70) could be removed by heating to 90 ! 100 °C. This “dehydrated” material proved to be synthetically useful and could be exhaustively silylated and stannylated in good to fair yields. The structures of Si8O20(SnMe3)8, Si8O20(SiMe3)8, and Si8O20(TiCp2Cl)8 are reported.