Site-Isolated Pt-SBA15 Materials from Tris(tert-butoxy)siloxy Complexes of Pt(II) and Pt(IV)

Two novel tris(tert-butoxy)siloxy complexes of Pt(II) and Pt(IV) were prepared in high yields, (cod)Pt[OSi(O'Bu)(3)](2) (1; 87%; cod = 1,5-cyclooctadiene) and Me3Pt(tmeda)[OSi(O'Bu)(3)] (2; 81%; tmeda = N,N,N',N'-tetramethylethylenediamine). The structures of these compounds were determined by multinuclear NMR spectroscopy and by single-crystal X-ray analysis. The thermolytic chemistry of I and 2 in the solid state was studied by thermogravimetric analysis. The thermal decomposition of these complexes resulted in the formation of Pt metal, with the elimination of HOSi(O'Bu)(3), Precursors I and 2 react with the surface Si-OH groups of mesoporous SBA15 silica to generate surface-supported Pt centers. The coordination environments of the Supported Pt centers in these new materials, termed Pt(II)SBA15 and Pt(IV)SBA15, were investigated using Fourier-transform infrared spectroscopy, X-ray absorption near-edge spectroscopy, and extended X-ray absorption fine structure analysis. These materials were also characterized using N, porosimetry, powder X-ray diffraction and transmission electron microscopy. Comparisons with the molecular precursors 1 and 2 revealed many similarities, and the results are indicative of isolated Pt(II) and Pt(IV) centers. In addition, isolated Pt centers proved to be robust in inert atmosphere to 150-200 degrees C, which is similar to the decomposition temperatures of 1 and 2.