Reaction of the framework 3d-organometallosiloxanes with acetylacetone

Abstract

A reaction of acetylacetone with the framework sandwich-type metallosiloxanes (MOS) of general formula [PhSiO2]6M6[PhSiO2]6, where M = Cu, Ni, Mn, was studied by GPC, 1H and 29Si NMR spectroscopy, X-ray diffraction, elemental and functional analysis. The reaction involved replacement of the metal atoms with the hydrogen atoms and is accompanied by the formation of the corresponding chelate complexes M(acac)2. Displacement of the metal from the framework MOS leads to the destruction of molecular skeleton and formation of phenylsiloxanes containing Si-OH groups. The yield and composition of the reaction products considerably depend on the nature of the metal in [PhSiO2]6M6[ThSiO2]6. A selective substitution of the metal leads to the stereoregular hexahydroxyhexaphenylcyclohexasiloxane, [PhSiO(PH)]6, cis-isomer. The structure and composition of the crystalline hexahydroxyhexaphenylcyclohexasiloxane obtained were confirmed by 29Si NMR spectroscopy, X-ray diffraction study, and functional analysis, while its TMS derivative was studied with 1H NMR spectroscopy and GPC. Using a framework manganese phenylsiloxane as an example, a reversible character of the process has been established and an alternative synthesis of this compound from hexahydroxyhexaphenylcyclohexasiloxane and Mn(acac)2 has been accomplished for the first time.