Selectively Tunable Domino Reaction of 1,3-Diphenylpropane-1,3-dione on the Ethoxy-Silicon Core

The reaction of (EtO)(3)SiCl with 1,3-diphenylpropane-1,3-dione in dichloromethane yields an ionic hexacoordinate compound featuring three chelating 1,3-diphenylpropane-1,3-dionato ligands as proven by its X-ray structure and multinuclear NMR studies in a fast domino reaction. With a proper selection of the solvent (toluene) and the reaction time, the intermediates of the reaction sequence can be selectively obtained. With an excess of the starting chlorosilane and short reaction times, the tetracoordinate silane can be obtained by the replacement of the chloro substituent. This compound shows a dynamic behavior according to its C-13 NMR spectrum, involving its pentacoordinate isomer, which is only slightly less stable according to DFT calculations. The hemilabile ethoxy group can easily be replaced by a further 1,3-diphenylpropane-1,3-dionato ligand, yielding the neutral hexacoordinate silane with two chelators and two ethoxy groups, as characterized by X-ray crystallography and multinuclear NMR studies.