Electronic structure of Co4(CO)12

The electronic structure of the Co₄(CO)₁₂ cluster has been studied by the extended semiempirical INDO method. The MO diagrams, atomic valences, and bond multiplicities are analyzed for the T_d and C_3v conformations of Co₄(CO)₁₂. Assignment of the electronic spectrum is suggested; the electronic structure of the lowest electronic-excited states is considered.St. Petersburg State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 34, No. 6, pp. 20–30, November–December, 1993.Translated by L. Smolina     

Limits of isomorphous substitution of molecules in normal paraffins as a function of temperature

The limits of isomorphous substitutions and the symmetry of synthetic binary solid solutions of paraffins C_nH_2n+2 with n=17–24 have been studied by X-ray diffraction and thermal X-ray diffraction. Principles of isomorphous substitutions of paraffin molecules are suggested which take into consideration the length (n), the symmetry (parity of n), and the intensity of thermal rotational motion of component molecules.St. Petersburg State University. Translated fromZhurnal Strukturnoi Khimii Vol. 34, No. 4, pp. 117–127, July–August, 1993.Translated by T. Yudanova     

Synthesis of substituted 2,5-diazabicyclo[2.2.1]heptanes

A new method is proposed for the synthesis of substitituted 2,5-diazabicyclo[2.2.1]heptanes from 1-(tert-butoxycarbonyl)-4-tosyloxy-2-(tosyloxymethyl)pyrrolidine.¹H NMR spectroscopy indicated multiple conformations of 2-(tert-butoxycarbonyl)-2,5-diazabicyclo[2.2.1]heptanes in solution.St. Petersburg State University, 198904 St. Petersburg, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 501–503, April, 2000.     

Acidity function scale for H2SO4 solutions in phenol-acetone solvents with low water content at 25°C

The indicator method was employed to measure the acidity function H ₀ ^S of H₂SO₄ solutions in solvents consisting of an equimolar mixture of phenol and acetone with 0.8% water (from 3.6·10^–4 to 2.6·10^–2 M H₂SO₄) and 2.5% water (from 4.3·10^–4 to 0.32 M H₂SO₄) and of phenol and acetone in a molar ratio of 1:1.5 with 0.67% water (from 1.63·10^–4 to 7.77·10^–2 M H₂SO₄) and 2.09% water (from 4.49·10^–4 to 0.35 M H₂SO₄) at 25°C. The indicators employed were 4- and 2-nitroaniline.Deceased.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. Lenneftekhim Scientific-Commercial Association, St. Petersburg. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 72–78, January, 1992.     

Free radical copolymerization of 1-vinyl naphthalene with styrene,methyl methacrylate,and acrylonitrile

Investigations on free radical copolymerization of 1-vinyl naphthalene (1-VNph, monomerM ₂) with styrene (St), methyl methacrylate (MMA) and acrylonitrile (AN) (monomersm ₁) in bulk at 60°C with AIBN as initiator are presented. Relative reactivity ratios were calculated by the Kelen-Tüdös method yielding:r _st=0.70 ±0.23 andr _1–VNph=2.02 ±0.40 for system St/1-VNph;r _MMA=0.32 ±0.10 andr _1–VNph=0.57 ±0.07 for system MMA/1-VNph andr _AN=0.11 ±0.03 andr _1–VNph=0.45 ±0.09 for system AN/1-VNph.Q, e values for 1-VNph according to Alfrey, Price scheme were calculated toQ _1–VNph=1.02,e ₁–VNph=–0.62.     

Donor-acceptor complexes of heteroaromatic N-oxides. A review

Petrozavodsk State University, 185640 Petrozavodsk and St. Petersburg State University, 198904 St. Petersburg. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 760–773, June, 1995. Original article submitted December 24, 1994.     

Reaction of 5-hydroxy-3,3,5-trimethylisoxazolidine with acrylic acid esters

The reaction of 5-hydroxy-3,3,5-trimethylisoxazolidine with methyl, ethyl, and tert-butyl acrylates, proceeds as Michael addition, and produces previously, unknown 5-hydroxy-3,3,5-trimethylisoxazolidine-2-propionic acid esters. The structures of the obtained products are proved by¹H and¹³C NMR spectroscopy and by their subsequent transformation into 5-hydroxy-3,3,5-trimethylisoxazolidine-2-propionic acid.Institute of High-Molecular Compounds, Russian Academy of Sciences, St. Petersburg 199004, Russia; St. Petersburg State University, St. Petersburg 198904, Russia Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 945–947, July, 1999.     

Thermal Analysis of Poly(AN—co—St) and Poly(AN—St—MMA)

Poly(AN—co—St) (PAS) and poly(AN—St—MMA)(PASM) were synthetized by emulsion polymerisation. The glass transition temperatures (T_g) of the copolymers and the relationship between T_g and the components of the copolymers were investigated by differential scanning calorimetry. The results show that T_g for the AN—St bipolymers has apeak value in the range 115–118°C at a content of 50 mass% St. When methyl methacrylate was added, the T_g of the terpolymer was decreased by about 2–6°C.The thermostability and the activation energy E of degradation were determined by thermogravimetric analysis.This revised version was published online in November 2005 with corrections to the Cover Date.     

Methods for the synthesis of mono- and polynuclear NH-tetrazoles. (Review)

Data on methods for the synthesis of monocyclic and polynuclear NH-unsubstituted tetrazoles are reviewed.Dedicated to Prof. H. Elguero on the occasion of his 65th birthday.St. Petersburg State Technological Institute (Technical University), St. Petersburg 198013, Russia; Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 867–884, July, 2000.     

Synthesis and structures of pyridoannelated 1,2,3,4-tetrazine 1,3-dioxides

Treatment of 2- and 4-amino-3-(tert-butyl-NNO-azoxy)pyridines with nitrating agents (N₂O₅or NO₂BF₄) afforded the first representatives of pyridoannelated 1,2,3,4-tetrazine di-N-oxides, viz., pyrido[2,3-e][1,2,3,4]tetrazine 1,3-dioxide (9), 7-nitropyrido[2,3-e][1,2,3,4]tetrazine 1,3-dioxide (10), and pyrido[3,4-e][1,2,3,4]tetrazine 2,4-dioxide (11). These compounds were studied by ¹H, ¹³C, and ¹⁴N NMR spectroscopy. The 1:1 complex of compound 10 with benzene was studied by X-ray diffraction analysis.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2471–2477, November, 2004.     

Radiation-induced copolymerization of styrene/n-butyl acrylate in the presence of ultra-fine powdered styrene–butadiene rubber

Styrene (St)/n-butyl acrylate (BA) copolymers were prepared by two-stage polymerization: St/BA was pre-polymerized to a viscous state by bulk polymerization with initiation by benzoyl peroxide (BPO) followed by ⁶⁰Co γ-ray radiation curing. The resultant copolymers had higher molecular weight and narrower molecular weight distribution than conventional methods. After incorporation of ultra-fine powdered styrene–butadiene rubber (UFSBR) with a particle size of 100 nm in the monomer, the glass transition temperature (T_g) of St–BA copolymer increased at low rubber content. Both the St–BA copolymer and the St–BA copolymer/UFSBR composites had good transparency at BA content below 40%.     

The molecular complex of 4-(N-pyridinium)pyridine-N-oxide chloride with tetracyanoethylene in the synthesis of substituted pyridine N-oxides

The structure of the complex of 4-(N-pyridinium)pyridine-N-oxide chloride with tetracyanoethylene was studied by¹³C NMR spectroscopy. The results of the investigation, suggesting the use of this complex in the synthesis of substituted pyridine derivatives, were conformed experimentally by its reaction with oxygen and with nitrogen-containing nucleophiles.Petrozavodsk State University, Petrozavodsk, 185640. St. Petersburg State University, St. Petersburg, 198904. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 184–186, February, 1995. Original article submitted December 24, 1994.     

Comparative study of the structure of microlayering water-dioxane and water-dimethylsulfoxide solutions

The infrared absorption spectra of water in the water-dioxane and water-dimethylsulfoxide systems have been investigated in a wide range of concentrations. Absorption bands of differen: forms of water present in solution have been identified. The state of internal water in aqueous microregions in both systems is characterized by increased stability. It is proposed that the specific state of the internal water of microregions is the motive force of the microlayering process hindering its ransition into ordinary macrolayering. Consecutive microlayering stages at varying concentrations of the nonelectrolyte are considered. The behavior of protein molecules in different microlayering solverts has been studied.St. Petersburg State University. Translated fromZhurnal Struktumoi Khimii, Vol. 34, No. 4, pp. 83–88, July–August, 1993.Translated by L. Smolina     

Composition and structure of the novel complex Rh(CO)·(Ph2PNH2)3

Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Institute of Applied Chemistry, St. Petersburg. Kazan Chemical Engineering Institute. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 6, pp. 140–145, November–December, 1992.     

Investigation of the catalytic activity of metal complexes fixed on a solid support. 10. Selective hydrogenation of allylbenzene in the presence of heterogeneous Pt-Sn-citrate complexes

New heterogeneous catalysts based on the complexes of platinum with tin(II) citrate were prepared. The catalysts exhibit high selectivity in the hydrogenation of allylbenzene to propylbenzene without increasing the rate of isomerization of the C=C bond. The activity of the complexes depends on the conditions and decreases with increase in the Sn:Pt ratio.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. St. Petersburg Technological Institute. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1287–1290, June, 1992.     

State of the Tb(III) and Nd(III) ions in concentrated solutions of electrolytes of various types

An investigation of the state of terbium and neodymium ions in solutions of various supporting electrolytes was conducted using an analysis of the electronic absorption spectra of Nd(II) and the fluorescence spectra of Tb(III). The supporting electrolytes selected were the salts LiSCN, LiCl, MgCl₂, NaCl, and CsCl, the concentration of which was varied within wide limits. The neodymium and terbium chloride concentrations were kept constant in all the solutions and equal to 0.015 and 0.03 M, respectively. To eliminate the influence of hydrolysis on the experimental results, all the solutions were acidified with hydrochloric acid (0.1 M).St. Petersburg University. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 2, pp. 105–111, March–April, 1993.     

Synthesis of ethers and esters of 1,4-di-N-oxide of 2,3-bis(hydroxymethyl)quinoxalm under conditions of interfacial catalysis

Esters and ethers of the 1,4-di-N-oxide of 2,3-bis(hydroxymethyl)quinoyaline have been obtained under conditions of interfacial catalysis in a chloroform-water system. The catalytic activities of tetrabutylammonium bromide and cetyltriethylammonium bromide have been compared in the synthesis of the acetate, benzoate, and 4-nitrobenzoate of the 1,4-di-N-oxide of 2,3-bis(hydroxymethyl)quinoxaline.St. Petersburg State Technological Institute, St. Petersburg 198013. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 816–820, June, 1994. Original article submitted June 29, 1994.     

Adamantylazoles. Acid-catalyzed adamantylation of 1,2,4-triazoles

The reaction of 1-adamantanol with 1,2,4-triazole in sulfuric acid forms 1-adamantyl derivatives. In boiling chloroform containing traces of sulfuric acid, a mixture of isomeric N-adamantyl-1, 2, 4-triazoles is obtained. It is shown that 1-adamantyl carbocation is formed at a sulfuric acid concentration above 70%.St. Petersburg State Technological Institute, St. Petersburg 198013. N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913. Translated from Khimiya Geterotsklicheskii Soedinenii, No. 8, pp. 1078–1087, August, 1996. Original article submitted June 7, 1996.     

Reactive-field theory for molecules in the surface layer of a liquid

Analytic formulas are derived for the solvation energy of molecules adsorbed in the surface layer of a liquid. These are analogs of the Born and Onsager formulas for the bulk phase. Deriving the solvation energy involves decomposing the molecular characteristics, which is done by quantum-chemical calculation.St. Petersburg University. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 2, pp. 3–10, March–April, 1993.     

Synthesis and study of the biological activity of fragments of salmon calcitonin II

A number of fragments of salmon calcitonin II possessing analgesic activity of the nonopioid type have been synthesized.Institute of High-Molecular-Mass Compounds, Russian Academy of Sciences. Institute of Experimental Medicine, Russian Academy of Medical Sciences, St. Petersburg. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 126–132, January–February, 1993.