Preparation and reactivity of metal-containing monomers

Homo- and copolymerization of vanadium-containing monomers (VCM) have been studied. Radical homopolymerization of VCM is accompanied by some side reactions, such as monomer disproportionation, copolymerization with ligandin situ, cyclopolymerization, V⁵⁺V⁴⁺ reduction,etc. These reactions complicate the interpretation of the results obtained. The character of radical copolymerization of VCM with styrene or acrylonitrile is preferably radical complex. Catalytic properties of vanadium-containing homo- and copolymers (in combination with organoaluminum compounds as cocatalysts) in Ziegler-Natta ethylene polymerization have been studied. It has been shown that the products inherit the properties of immobilized polymer catalysts.For Part 39, seeIzv. Akad. Nauk, Ser. Khim., 1994, 1047 [Russ. Chem. Bull., 1994, 43, 983 (Engl. Transl.)].Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2139–2144, December, 1994.     

Preparation and reactivity of metal-containing monomers

Thermal transformations (at 340 to 390 °C) of coprecipitates of iron and cobalt acrylates, [Fe₃O(CH₂CHCOO)₆OH][Co(CH₂CHCOO)₂]_2.4 (1) and [Fe₃O(CH₂CHCOO)₆OH][Co(CH₂CHCOO)₂]_1.5·3H₂O (2), are studied. The dependence of the degree of gas evolution () on time is described by the equation () wherek ₁=2.3 · 10¹² · exp[–49500/(RT)] s^–1,k ₂=6.0 · 10⁶ · exp[–33000/(RT)] s^–1 andk ₁=2.6 · 10¹² · exp[–49000/(RT)] s^–1,k ₂=6.6 · 10⁵ · exp[–30000/(RT)] s^–1 for cocrystallizates1 and2, respectively. The coefficient ₁ decreases as the temperature increases. The value of ₁ for compound1 is higher than that for compound2. The composition of products of the transformations of1 and2 are studied. The main solid state products of the decomposition are nanometer-sized particles of cobalt ferrite, CoFe₂O₄, with a narrow size distribution stabilized by the polymeric matrix. The thermal transformations of cocrystallizates1 and2 include dehydration, thermal decomposition, copolymerization in the solid state, and decarboxylation of the metallocarboxylate groups of the polymer. The effect of the ratio between the Fe clusters and the Co-containing fragments on the process of thermal transformation is analyzed.For Part 40, seeRuss. Chem. Bull., 1994,43, 2020.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 885–893, May, 1995.The authors are grateful to A. N. Titkov for optical microscopic and electron microscopic studies.     

Heterometallic complexes of titanium(IV) and tin(IV) chlorides with nickel(II) and cobalt(II) enaminoketonates and enaminoiminates

Heterometallic complexes have been synthesized by the interaction of Ti^IV and Sn^IV chlorides with Ni^II and Co^II enaminoketonates and enaminoiminates. The complexes were characterized by elemental analyses, magnetic susceptibility and i.r. spectroscopy. The catalytic properties of the complexes in the preparation of linear low density polyethylene have been studied. TMC 2192     

Preparation and reactivity of metal-containing monomers

Vinylporphyrins containing one vinyl group at the pyrrole or benzene ring and their complexes with Cu²⁺ and Zn²⁺ have been obtained by the Wittig reaction. Compounds obtained were characterized by physicochemical methods. X-ray diffraction analysis of 5-(4-vinylphenyl)-10,15,20-triphenylporphyrin has been carried out. It is likely that the inclusion of the vinyl group is accompanied by weak electron effects on the macrocycle. No nonequivalence of N-H bonds is observed in initial macrocycles.     

Reactivity of metal-containing monomers 71. Synthesis of nanosized quasicrystals and related metallopolymer composites

The methods for the preparation of quasicrystalline intermetallic compounds in the protective matrix in the systems Al₆₅Cu₂₂Fe₁₃ and Al₅₄Cu₉Mg₃₇ were developed. They are formed both earlier and from elements during the formation of a metallopolymer composite material. Three methods of preparation are optimal: from low-dimensional powders of quasicrystals and film-forming polymers, by the in situ formation of quasicrystals during the thermal decomposition of the corresponding precursors, and via the thermal polymerization of metal-containing monomers (components of quasicrystals) followed by the controlled pyrolysis of the metallopolymers that formed. The metallopolymer composite obtained by the incorporation of Al₆₃Cu₂₂Fe₁₃ into the high-density polyethylene or polyacrylamide matrix affords up to 10 wt.% cubic phase of ??-Al₅₀(Cu,Fe)₅₀. The products of thermal decomposition of the low-molecular-weight precursors are a mixture of the quasicrystalline (Al₆₅Cu₂₂Fe₁₃) and crystalline (cubic ??-Al₅₀(Cu,Fe)₅₀ and tetragonal ??-Al₇Cu₂Fe, Al₂Cu) phases. The thermolysis of the metallo-polymer composition yields a finely dispersed powder, whose main component is an alloy Al₇Cu₃Mg₆ with an admixture of the Al₂CuMg phase.     

Metal-containing nanoparticles with core-polymer shell structure

Metal-polymer nanocomposites, which comprise nanoparticles of metals and/or their oxides and carbides uniformly distributed in stabilizing polymer matrices, are prepared through solid-phase polymerization of metal-containing monomers followed by controlled thermolysis of synthesized metal-containing polymers. Using X-ray diffraction, electron microscopy, ferromagnetic resonance, and IR spectroscopy, it is shown that nanoparticles present in these systems have a characteristic core-shell structure that comprises a metal-containing core and a surface layer, i.e., a polymer shell. Parameters of the components are estimated.     

Effect of Freon matrices on the intermediates stabilized in X-ray irradiated 1,7-dioxaspiro[5,5]undecane solutions at 77 K

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Orientational order of guest molecules in aligned liquid crystal as measured by EPR and UV–vis techniques

Orientational order of guest molecules in aligned liquid crystal 4-cyano-4′-pentylbiphenyl (5CB) is studied via optical dichroism and electron paramagnetic resonance (EPR) spectra measurements. The guest molecules used are bifunctional molecules bearing paramagnetic nitroxide group and photochromic azobenzene moiety. The bifunctional probe with rigidly bonded nitroxide and azobenzene moieties was found to align as a whole, while flexible long spacer between the moieties provides independent alignment for the nitroxide and azobenzene parts. Intermolecular interactions responsible for the alignment of azobenzene and nitroxide moieties of the probe molecules are discussed. The molecules with cis-configuration of azobenzene moiety are able to align in the liquid-crystalline medium, but to a lesser extent than the molecules with trans-configuration. Directions of orientational axes and characteristics of rotational mobility of spin probes are determined. Second, fourth and, in some cases, sixth rank order parameter values are found.     

Preparation and reactivity of metal-containing monomers

The stability of chelates of several bivalent metals with poly(methacryloylacetone) was determined by pH titration. Two models in which the fragment of a polymeric molecule in the coordination sphere of a metal was approximated by either a mono- or a bidentate ligand were considered. Different mechanisms of complex formnation were realized depending on the nature of M(II).For part 29 seeIzv. Akad. Nauk, Ser. Khim., 1993, 975 [Russ. Chem. Bull., 1993,42, 937 (Eng.Transl.)].Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1063–1066, June, 1993.