Synthesis of tetrakis(triethylsiloxy)titanium and tetrakis(triethylsiloxy)tin

Summary By the metathetic reaction of sodium triethylsiloxide with titanium tetrachloride and with tin tetrachloride, tetrakis(triethylsiloxy)titanium and tetrakis(triethylsiloxy)tin were synthesized.     

Vibrational spectra and stereoisomerism of the hexopyranose ring in epoxysaccharides

Journal of Structural Chemistry - Investigation of the potential surface of methyl 2,3-anhydro-2,3,4-trideoxy-β-D-lyxohexopyranoside has shown that the molecule has seven conformers with...     

Coordination of N-Substituted Porphyrins with Simple and Chelate Zinc Salts in DMSO

The effect of peripheral substitution in the porphyrin macrocycle (₂OEtP, H₂TPP) of the nature of the N-substituent (X = Me, Ph) and of the anion in the salt solvate (A = ^–, NO₃ ^–, ^–) on the complexation of the N-substituted porphyrins with zinc salts in DMSO is studied. The positions of the bands in the electronic absorption spectrum of the (A)M(N-X)P metal complex were found to depend only slightly on the nature of the A anion in the composition of the coordination sphere of the complex. An inhibition of coordination of the N-substituted ₂TPP derivatives by zinc nitrate was discovered that is not typical of porphyrins proper. The type of hybridization of the substituted nitrogen atom in the porphyrin molecule is discussed. A mixed type of hybridization is suggested: the sp ²- and p ³-forms in the ligands and an almost complete transition to the p ³ form in the N-substituted metal complexes.     

Rearrangements of 1-oxa-2-azoles. 2. Structure and isomerization of pentamethylene-amidoximes of 4-aminofurazan-3-carboxylic acid

The Z-oxime of the pentamethyleneamide of 4-aminofurazan-3-carboxylic acid isomerizes — rapidly in acid media, slowly in the absence of acid — to the E-oxime which at 120–140C undergoes alkali-catalyzed rearrangement to 4-piperidinofurazan-3-carboxyamidoxime.For Communication 1 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 122–123, January, 1991.     

Nucleophilic reactions of polydialkylcyclosilazanes

A study is made of the catalytic condensation polymerization of polydialkylcyclosilazanes [RR'SiNH]_n (n=3,4; R=CH₃, C₂H₅; R'=C₂H₅, C₄H₉, C₆H₁₃, C₉H₁₉) in the presence of small amounts of nucleophilic reagents, to give compounds of the general type R₅R₆'Si₆N₃(NH)₂ and oligomers. The reactivities of polydialkylsilazanes decrease with increase in aliphatic group chain length.     

Synthesis and structure of the new binuclear complex η5-C5H5(CO)2Fe-η1-C5H4(CO)2Fe-CH3

Conclusions The new binuclear complex ⁵-C₅H₅(CO)₂Fe-¹-C₅H₄(CO)₂Fe-CH₃ was synthesized. Its structure was established by x-ray crystallographic analysis.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 437–440, February, 1986.     

Structure of organophosphorus compounds

Journal of Structural Chemistry -     

(Z)-3-p-tolylsulfinylacrylonitrile as a chiral dienophile: diels-alder reactions with furan and acyclic dienes

The behavior of (Z)-3-p-tolylsulfinylacrylonitrile (1) as a chiral dienophile has been evaluated from its reactions with furan and acyclic dienes. Electrostatic interactions of the cyano group with the sulfinyl one restrict the conformational mobility around the C-S bond, thus controlling the pi-facial selectivity, which is almost complete in all cases, the approach of the diene from the less-hindered face of the dienophile (that bearing the lone electron pair) in the predominant rotamer being the favored one. The regioselectivity is also completely controlled by the cyano group. Additionally, the reactivity of compound 1 as well as its endo-selectivity are both higher than those observed for the corresponding (Z)-3-sulfinylacrylates, thus proving the potential of sulfinylnitriles as chiral dienophiles.     

Some physical properties of polyorganosiloxanes. I. Linear polyorganosiloxanes

Some physical properties of linear polydimethylsiloxanes have been studied. The states and transitions in polydimethylsiloxanes have been investigated by using the method of dynamic heat capacity and a thermomechanic method in the temperature range from ?150 to +200°C. The temperature dependence of primary and secondary crystallization has been studied by optical, calorimetric, and x-ray methods.     

Gauge Nambu-Jona-Lasinio model as a low-energy approximation of QCD

For the Nambu-Jona-Lasinio model in the regime of dynamical symmetry breaking we formulate principles for selecting 4-fermion models as a low-energy approximation of QCD. On their basis, by means of an effective potential, we consider the possibility of their intrinsic stabilization at a finite cutoff momentum . In the framework of the approach, we investigate the influence of the gluon condensate on the parameters of the model and the effective lagrangian in the low-energy region.St Petersburg State University. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 93, No. 1, pp. 67–86, October, 1992.