Synthesis and study of the structure of cage-like metallosiloxanes with pair combinations of 3d transition and alkaline earth metals

The selective replacement of Na ions in cage-like (Cu,Na) organosiloxanes in reactions with divalent metal halides was studied. The sandwich-like isomer [PhSiO₂]₆Cu₄Na₄[PhSiO₂]₆ forms the corresponding bimetallic complexes [PhSiO₂]₆Cu₄M₂[PhSiO₂]₆ (M = Cu, Zn, Mg, Sr, Ba) retaining a sandwich-like structure (in 60–90% yields) regardless of the metal ion size in MCl₂. Under similar conditions, the reactions of the globular isomers [RSiO₂]₁₂Cu₄Na₄ (R = Ph, Me, Vin) with CuX₂ (X = Cl or Br) afforded insoluble polymer products. The reaction in dioxane or THF in the presence of DMSO gave the crystalline globular-type metal complexes [RSiO₂]₁₂Cu₄[CuX]₄, in which Na ions are replaced by CuX groups. The compositions and structures of the synthesized metal complexes were studied by X-ray diffraction, elemental analysis, and destructive silylation combined with gel permeation chromatography and ¹H NMR spectroscopy.     

Synthesis of 3-[tris(ψ-trifluoropropyl)sily]propyldimethylsilane

Monofunctional silane containing a tris(ψ-trifluoropropyl) fragment was synthesized in high yield by a series of successive reactions including the Grignard reaction, hydrosilylation, and reduction. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 808–809, April, 1999.     

Synthesis of telehelic oligodimethylsiloxanes with 4-carboxypyrrolidone fragments: rheological and thermal properties

Telehelic oligodimethylsiloxanes containing 4-carboxypyrrolidone fragments were synthesized by the reactions of oligodimethylsiloxanes bearing terminal 3-aminopropyl groups with itaconic acid. The thermal and rheological properties of the obtained polymers were studied. The activation energies of viscous flow of the oligomers obtained and the previously synthesized oligodimethylsiloxanes containing terminal fragments of undecenoic or benzoic acid are compared.

     

Synthesis of bithiophenesilane dendrimer of the first generation

The synthesis of tris{5′-[methylbis(2-thienyl)silyl]2,2′-bithienyl-5-yl} methylsilane, a first-generation bithiophenesilane dendrimer, is described. The conditions of effective formation of methyltrithienylsilane were found; methyltris(5-bromo-2-thienyl)silane and a number of other monofunctional derivatives of methyltrithienylsilane were synthesized for the first time. The advantages and drawbacks of the Suzuki and Kumada reactions for the formation of bithienyl fragments in the synthesis of oligothienylsilane dendrimers are discussed.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 673–679, March, 2005.     

Reaction of the framework 3d-organometallosiloxanes with acetylacetone

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.     

Hydrolytic polycondensation of sodiumoxymethyl(dialkoxy)silanes as a method for producing linear poly[(sodiumoxy)methylsilsesquioxane]

Polyfunctional linear poly[(sodiumoxy)methylsilsesquioxanes] are obtained via the hydrolytic polycondensation of sodiumoxymethyl(dialkoxy)silanes. Blocking of sodiumoxy groups with vinyl(dimethyl)chlorosilane is employed to obtain vinyl(dimethyl)siloxane replicas of polyfunctional matrices. The linear structure of the polymers is studied by GPC, NMR spectroscopy, and elemental analysis. The specific properties of poly[vinyl(dimethylsiloxy)methylsilsesquioxane] are investigated and are shown to be primarily related to an abnormally dense organization of polymer coils in solutions.     

Diphilic carbosilane dendrimers with different densities of the hydrophilic layer

A universal method for the synthesis of hydrophilic dendrimers was considered. The method is based on a combination of carbosilane dendrimers with different molecular organizations and hydrophilizing agents, viz., substituted hydride silanes containing one and three protected hydroxyl groups. The combination of a limited set of the mentioned reagents makes it possible to control the ratio of hydrophilic and hydrophobic moieties of the molecular structure in wide limits. A simple and convenient method for the removal of trimethylsilyl protection of hydroxyl groups in the surface layer of dendrimers was developed.