Electrochemical reduction of 1,1-dihalo-2,2-disubstituted cyclopropanes

The electrochemical reduction of 1,1-dihalo-2-R-2-methylcyclopropanes was studied by polarography and preparative electrolysis. A mixture of stereoisomeric monoboro- and monochlorocyclopropanes was obtained with preparative yield of 60–70% in preparative electroreduction in methanol against a background of 0.1 M LiClO₄. In the case of bromine derivatives of cyclopropanes (except when R = CN) an effect was found on the part of the current density on the ratio of cis and trans isomers, which was interpreted as a change, in dependence on current density, of the contributions of the reactions of reduction of the starting compounds (S_N2 mechanism) and ionic pairs (S_N1 mechanism). The effect of the solvent (CHCl₃, DMF, DMSO, MeOH) and background salt (LiClO₄, Et₄NBr) on the ratio of stereoisomers is in agreement with this interpretation.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Science Center, Russian Academy of Sciences, Kazan. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 2023–2032, September, 1992.     

Influence of the conditions of manufacture of nanomeric zirconium dioxide,stabilized with yttrium oxide,on its catalytic properties in the oxidation of CO

The morphological and catalytic properties of samples of nanomeric zirconium dioxide, stabilized with yttrium oxide, manufactured via the effect of a UHF field during the process of drying precipitated zirconium hydroxide and calcination at temperatures from 300 to 1000 °C, were studied. It was shown that the highest activity in the oxidation of CO occurred with 40 nm particles of zirconium dioxide prepared at 1000 °C. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 2, pp. 96–101, March–April, 2007.     

Influence of oxygen on catalytic properties of supported palladium catalysts in CO hydrogenation

It has been established that the addition of oxygen to synthesis gas has a positive effect of the activity and selectivity of supported palladium catalysts in methanol synthesis. The degree of the effect of oxygen depends on the chemical nature of the support and the conditions of catalysis, preceding the addition of oxygen to the reaction mixture. The probable causes for the influence of oxygen on the catalytic properties of palladium, supported on oxide supports, have been discussed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 5, pp. 557–563, September–October, 1989.     

Synthesis and crystal structure of divaleratobis(nicotinamide)copper(II)

A copper(II) valerate complex with nicotinamide (L) [CuL₂(C₄H₉COO)₂] (I) has been synthesized and studied by IR spectroscopy and thermogravimetry. The crystal structure has been determined. The crystals of 1 are monoclinic, a = 11.297(1) Å, b = 6.666(1) Å, c = 16.873(2) Å, b = 108.50(1)°, V = 1204.9(3) ų, Z = 2, space group P2₁/c. The structural units of the crystal of I are centrosymmetric tetragonal bipyramidal (4+2) complex molecules. The equatorial positions of the bipyramid are occupied by trans-arranged pairs of O (Cu-O, 1.973 Å) and N (Cu-N, 2.006 Å) atoms, and the axial positions are occupied by the second O atoms of the valerate anions located at longer distances (Cu-O, 2.506 Å). The supramolecular associates formed in the crystal are layers of hydrogen-bonded complexes. The disordered hydrocarbon “tails” of the valerate groups point toward the interlayer space.     

Coordination compounds of Co(II), Ni(II), and Cu(II) valerates and benzoates with semicarbazide

Complexes of Co(II), Ni(II), and Cu(II) valerates and benzoates with semicarbazide were prepared. The compounds were characterized by chemical analysis, X-ray phase analysis, IR spectroscopy, diffuse reflection spectroscopy, and thermal gravimetric analysis.     

Synthesis in the phenothiazine series

Quaternary salts of imidazo[4,5,1-k,l]phenothiazine were reduced with potassium borohydride to 1,2-dihydro-2-methylimidazo[4,5,1-k,l]phenothiazine, which was converted to 1,2 dihydro-2-methylimidazo[4,5,1-k,l]phenothiazine-1-thione and 1-methylamino-10-formylphenothiazine. The latter was hydrolyzed to 1-methylaminophenothiazine, which was also obtained by reduction of methyl phenothiazine-1-carbamate. The PMR and IR spectra of some of the derivatives are discussed.See [1] for communication XXXV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 372–374, March, 1974.     

Electron correlation effects on the shape of the Kohn–Sham molecular orbital

Even systems in which strong electron correlation effects are present, such as the large near-degeneracy correlation in a dissociating electron pair bond exemplified by stretched H₂, are represented in the Kohn–Sham (KS) model of non-interacting electrons by a determinantal wavefunction built from the KS molecular orbitals. As a contribution to the discussion on the status and meaning of the KS orbitals we investigate, for the prototype system of H₂ at large bond distance, and also for a one-dimensional molecular model, how the electron correlation effects show up in the shape of the KS σ _g orbital. KS orbitals φ^HL and φ^FCI obtained from the correlated Heitler-London and full configuration interaction wavefunctions are compared to the orbital φ^LCAO, the traditional linear combination of atomic orbitals (LCAO) form of the (approximate) Hartree-Fock orbital. Electron correlation manifests itself in an essentially non-LCAO structure of the KS orbitals φ^HL and φ^FCI around the bond midpoint, which shows up particularly clearly in the Laplacian of the KS orbital. There are corresponding features in the kinetic energy density t _s of the KS system (a well around the bond midpoint) and in the one-electron KS potential v _s (a peak). The KS features are lacking in the Hartree-Fock orbital, in a minimal LCAO approximation as well as in the exact one. Received: 11 December 1996 / Accepted: 10 January 1997     

Structure of the neutral metal complex Pt(dddt)2

A neutral metal complex, [Pt(dddt)₂]° (1), has been obtained by oxidation of the [Pt(dddt)₂]^– anion with excess (Bu₄N)AuBr₄ in nitrobenzene. Crystallographic data for 1a=17.854(9) Å,b=18.409(9) Å,c=4.717(5) Å, =68.83(2)°, space group P2₁/n,Z=4,d _calc=2.55 g/cm³. In1 two independent centrosymmetric [Pt(dddt)₂]° molecules are packed in stacks that form layers parallel to the (110) plane. The molecules of1 in the layers have shortened S...S contacts 3.491(9) Å, and 3.594(10) Å. The average bond lengths Pt-S 2.242(7) Å, S-C 1.71(2) Å and C=C 1.40(3) Å, together with the square-planar coordination of Pt in PtS₄, suggest considerable conjugation in the metal cycles.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1207–1209, July, 1993.     

Thermal stability and crystal structure of potassium fluoride monoperoxosolvate KF·H2O2

Potassium fluoride peroxosolvate KF-H₂O₂ was obtained upon action of a 30% aqueous solution of hydrogen peroxide on solid potassium fluoride dihydrate. As compared to other peroxosolvates, KF-H₂O₂ is characterized by the highest thermal stability: the decomposition rate constantk ₁, at 120°C is 1.4 10^–3 min^–1, the enthalpy of H₂O₂ addition to KF is 8.1 kcal/ mol. The correlation between the high stability of KF-H₂O₂ and the absence of catalytic properties of KF towards H₂O₂, and the formation of strong intermolecular O-H...F and intramolecular O-H...O hydrogen bonds in the crystal is discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 38–44, January, 1993.     

X-ray structural analysis of a novel organic metal (BEDT-TTF)4[Hg2Cl6]·PhCl

X-ray structural analysis has revealed that reaction of (BEDT-TTF)[HgCl₃]^– with PhCl leads to the formation of a cation-radical salt (BEDT-TTF)₄[Hg₂Cl₆]· PhCl, which exhibits a laminar crystal structure. The cationic layer is characterized by a grid or lattice network of contracted S...S intermolecular distances (3.396(4)–3.647(5) Å), which unite the BEDT-TTF cations in ribbons or bands, parallel to the [014] direction, and which also bind the ribbons together in a direction close to the [010] axis. The presence of this type of lattice network explains the metallic nature of the conductivity of this salt (BEDT-TTF)₄Hg₂Cl₆]·PhCl in the temperature range 300.0–1.5 K, and is the basis of assigning this salt to a new class of organic, two-dimensional conductors. The [Hg₂Cl₆]^2– anions and PhCl solvent molecules are united via secondary Hg...Cl 3.176(5) Å and Cl...Cl 3.480(6) Å interaction forces to form centrosymmetric tetramers [Hg₂Cl₆PhCl]₂ ^4–, stretched out along the [014] axis direction.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2062–2070, September, 1991.The authors wish to acknowledge R. N. Lyubovskaya for supplying the crystals and for helpful discussion of the results.