Time Positron Diagnostics of Metal β-Diketonates

The effects of the nature of the metal atom and -substituents in aluminum(III), chromium(III), cobalt(III), and iron(III) acetylacetonates on the lifetime and intensity of a long-lived component in positron and positronium annihilation were studied by the method of positron diagnostics. An addition of a positron to the -system of a chelate ring is supposed, which makes it possible to qualitatively estimate the basicities of the complexes. Annihilation of positrons and halogen-containing positronium -diketonates is accompanied by the formation of a protonated complex; for -organylthioacetylacetonates, annihilation follows the inhibition mechanism.     

Asymmetric synthesis of heteroorganic analogs of natural products. 6. (S)-α-amino-ω-phosphonocarboxylic acids

Alkylation, by -haloalkylphosphonates, of the Ni(II) complex of the Schiff base formed from glycine and (S)-2-N-(N¹-benzylprolyl)-o-aminobenzophenone has been used for the asymmetric synthesis of (S)-2-amino-4-phosphonobutyric and (S)-2-amino-5-phosphonovaleric acids.Institute of Bioorganic Chemistry and Oil Chemistry, Ukrainian Academy of Sciences, 250800 Kiev. A. N. Nesmeyanov Institute of Organometallic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 397–402, February, 1992.     

Boron difluoride acetylacetonate sulfenyl(selenyl) halides

By cleavage of disulfide and diselenide derivatives of the boron difluoride acetylacetonate the previously unknown sulfenyl(selenyl) chlorides and bromides were prepared. It was shown that these compounds could be involved into the substitution and addition reactions characteristic of sulfenyl(selenyl) halides.     

Asymmetrical synthesis of organometallic analogs of natural compounds. 8. Reactions of pentafluorobenzaldehyde with the Ni(II) complex of a schiff base of glycine and (S)-2-[N-(benzylprolyl)amino]benzophenone

Reaction of pentafluorobenzaldehyde with a Ni(II) complex of a Schiff base formed from glycine and (S)-2-[N-(benzylprolyl)amino]benzophenone yields, depending on the reaction conditions, the hitherto unknown, diastereo-and enantiomerically pure amino acids 2R,3S--(4-methoxytetrafluorophenyl)serine, 2S,3R--(4-methoxytetrafluorophenyl)serine, 2S,3S--(pentafluorophenyl)serine, and 2S,3R--(pentafluorophenyl)serine.A. N. Nesmeyanov Institute of Organometallic Compounds, Russian Academy of Sciences, 117813 Moscow. Institute of Bioorganic Chemistry and Petroleum Chemistry, Ukrainian Academy of Sciences, 252028 Kiev. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 687–693, March, 1992.     

Nitrogen-containing heterocycles from metal β-diketonates

Factors determining the reaction of metal β-diketonates with hydrazine, in particular the nature of central metal ion and structure of β-diketonate ligand, are discussed. The possibility for the preparation of other heterocyclic compounds via reaction of metal acetylacetonates with phenylhydrazine, o-phenylenediamine, urea, and thiourea was studied.     

α-substituted boron difluoride acetylacetonates

By treatment of α-substituted acetylacetone derivatives with boron trifluoride etherate a series of earlier unknown boron difluoride complexes is obtained. The series includes binuclear complexes containing boron in the chelate fragment connected via sulfur or selenium atom. Gas chromatographic and spectral characteristics of the obtained compounds were investigated. By means of chromato-mass spectrometry their reaction with hydrazine in acidic and alkaline media was studied.     

Fluorescence of polystyrene microspheres during photochemical synthesis of gold nanoparticles

The results of investigation of the fluorescence of carboxylated polystyrene microspheres in the process of photochemical synthesis of gold nanoparticles are presented. The introduction of an aqueous solution of hydrogen tetrachloroaurate (III) into an unirradiated polymer dispersion causes a decay of the excimer fluorescence in polystyrene at 335 nm. UV irradiation (λ_exc = 254 nm) of polystyrene dispersions in the presence of AuCl ₄ ^? ions leads to the formation of metal particles, which occurs after an induction period and affects the polystyrene fluorescence.     

Thermal decomposition of silicon-containing chromium and cobalt γ-[(alkylthio)(alkoxy)phosphorylthio]acetylacetonates

Thermal decomposition of silicon-containing chromium and cobalt γ-[(alkylthio)(alkoxy)phosphorylthio]acetylacetonates in air was studied by derivatography. Thermal decomposition of the monomeric metal chelates containing triethylsilyl groups starts from the elimination of the substituent at P, followed by oxidation of the γ-thioacetylacetonate group. Thermal oxidation of polyorganylsiloxanes with phosphorus-substituted γ-thioacetylacetonate fragments starts with the oxidation of the γ-thioacetylacetonate groups, followed by oxidation of the alkoxy and vinylthio groups at phosphorus.