Synthesis and characterization of some dimethylsilicon(IV) complexes with internally functionalized oximes: Crystal and molecular structure of [Me2Si{ONC(H)C4H3O-2}2]. Formation of mesoporous materials by the hydrolytic study of [Me2Si{ONC(CH3)C4H3O-2}2]

Reactions of Me2SiCl2 in a 1:2 molar ratio with internally functionalized oximes in the presence of Et3N in anhydrous benzene afford compounds of the type [Me2Si{ONC(R)Ar}2] {where R = Me, Ar = 2-C5H4N (1), 2-C4H3O (2), 2-C4H3S (3); R = H, Ar = 2-C5H4N (4), 2-C4H3O (5), 2-C4H3S (6)}. Molecular weight measurements of all these derivatives in freezing benzene and the FAB mass spectral studies of 1 and 6 indicate that these complexes are monomeric. The 1H and 13C{1H} NMR spectra suggest that the oximate moieties are monofunctional monodentate in solution. 29Si{1H} NMR signals appear in the region expected for tetra-coordinated dimethyl silicon atoms. Single crystal X-ray diffraction analysis of [Me2Si{ONC(H)C4H3O-2}2] (5) confirms the presence of a distorted tetrahedron as the immediate environment around silicon. Secondary weak β-donor bonding is also observed in the solid state, indicating that silicon is in the (4+2) coordination state. The TGA curve of [Me2Si{ONC(H)C4H3O-2}2] shows the high thermal stability and volatile nature of the complex. A comparison of hydrolytic studies of a mixture of [Me2Si{ONC(CH3)C4H3O-2}2] and Al(OPri)3 in a 1:2 molar ratio with those of pure Al(OPri)3 under similar conditions by the sol–gel technique suggests the formation of a silicon embedded amorphous powder 7 and γ-alumina 8, respectively. The variation in specific surface area, total pore volume and pore size indicate formation of mesoporous materials.

Dimethylsilicon(IV) complexes, [Me2Si{ONC(R)Ar}2], have been prepared and characterized. The X-ray structure (R = H, Ar = 2-C4H3O) confirms the presence of a distorted tetrahedral environment around silicon. Formation of a mesoporous material has been observed on hydrolysis of the complex (R = CH3, Ar = 2-C4H3O) in the presence of Al(OPri)3.Figure optionsDownload as PowerPoint slide