A. D. Vasiliev

Cell growth and accumulation of polyhydroxyalkanoates from CO2 and H2 of a hydrogen-oxidizing bacterium, Cupriavidus eutrophus B-10646.

Synthesis of polyhydroxyalkanoates (PHAs) by a new strain of Cupriavidus - Cupriavidus eutrophus B-10646 - was investigated under autotrophic growth conditions. Under chemostat, at the specific flow rate D=0.1h(-1), on sole carbon substrate (CO2), with nitrogen, sulfur, phosphorus, potassium, and manganese used as growth limiting elements, the highest poly(3-hydroxybutyrate) [P(3HB)] yields were obtained under nitrogen deficiency. In batch autotrophic culture, in the fermenter with oxygen mass transfer coefficient 0.460 h(-1), P(3HB) yields reached 85% of dry cell weight (DCW) and DCW reached 50 g/l. Concentrations of supplementary PHA precursor substrates (valerate, hexanoate, γ-butyrolactone) and culture conditions were varied to produce, for the first time under autotrophic growth conditions, PHA ter- and tetra-polymers with widely varying major fractions of 3-hydroxybutyrate, 4-hydroxybutyrate, 3-hydroxyvalerate, and 3-hydroxyhexanoate monomer units. Investigation of the high-purity PHA specimens showed significant differences in their physicochemical and physicomechanical properties.

Powder diffraction crystal structure analysis using derivative difference minimization : example of the potassium salt of 1-(tetrazol-5-yl)-2-nitroguanidine

The crystal structure of the potassium salt of 1-(tetrazol-5-yl)-2-nitroguanidine [K(C2H3N8O2)] was solved and refined from X-ray powder diffraction data by applying the derivative difference minimization (DDM) method. The compound is of interest as an energetic substance. The structure model was found from a Patterson search. The reflection intensities for the Patterson synthesis were derived from the powder profile by applying a newly developed DDM-based profile decomposition procedure. The use of the DDM method allowed successful location and unconstrained refinement of all the atomic positions, including those of three independent H atoms. The advantages of DDM in terms of the precision and reproducibility of the structural parameters are discussed in comparison to Rietveld refinement results. The failure to refine the H-atom positions by the Rietveld method was attributed to systematic errors associated with the background modelling, which are avoided by DDM.

Spin-glass magnetic ordering in CoMgGaO2BO3 ludwigite

Single crystal, needle shaped samples of diamagnetically diluted cobalt ludwigite CoMgGaO2BO3 have been grown by the flux method. X-ray diffraction and both dc and ac magnetic measurements are described. The unit cell volume changes significantly with dilution, from 328.31 A3 for the parent compound Co3O2BO3 to 345.46 A3 for CoMgGaO2BO3. The magnetic transition temperature is considerably lower for the latter compound (25 K against 43 K for Co2O2BO3). The dc magnetization temperature dependences are split between the field cooled and zero-field cooled regimes and the ac magnetic susceptibility temperature curves are frequency dependent, which indicates possible spin-glass freezing in the magnetic system.

1,2-dinitroguanidine.

The title compound, CH(3)N(5)O(4), is almost planar, and the conformation is fixed by two intramolecular N-H...O hydrogen bonds. Owing to the delocalization of pi-electron density over the whole molecule, there is through-conjugation, with the C-N, N-N and N-O bond lengths having values intermediate between those typical for the corresponding single and double bonds.

Crystal and Molecular Structure of Monoammonium Salt of 5‐nitroaminotetrazole

X‐ray structural investigation of the monoammonium salt of 5‐nitroaminotetrazole was performed. The crystals are orthorhombic: a = 10.077(1)Å, b = 17.009(1)Å, c = 6.6472(6)Å, V = 1139.33(17)Å3, space group Pbca, Z =8, ρcalc = 1.715 g/cm3. Monodeprotonation of 5‐nitroaminotetrazole during formation of the salt occurs at the N(4) nitrogen atom of the heterocycle. The anion has an almost flat structure; the bond lengths suggest delocalization of π‐electron density in the molecule. The negative charge is distributed among three nitrogen atoms and two oxygen atoms of the anion. Changes in the geometrical parameters of 5‐nitroaminotetrazole on monodeprotonation are considered.

Synthesis and Crystal Structure of Nitrosoruthenium Triammino Complex [RuNO(NH3)3Cl(H2O)]Cl2

This paper reports on a procedure for the synthesis of the compound [RuNO(NH3)3Cl(H2O)]Cl2. The complex was studied by IR spectroscopy and X-ray phase and X-ray diffraction analyses. Crystal data for RuCl3N4O2H11: a = 13.151(2), b = 6.852(1), c = 10.361(1) Å, V = 933.6(2) Å2, space group Pna21, Z = 4, dcalc = 2.181 g/cm3, dexp = 2.178 g/cm3. The structure consists of the [RuNO(NH3)3Cl(H2O)]2+ complex cations and Cl– anions. The compound crystallizes as small orange red isometric orthorhombic crystals well soluble in water and insoluble in concentrated hydrochloric acid and organic solvents and is stable when stored in air.

Polymorphism of KNaNbOF5 crystals

X-ray crystallography is used to analyze the concomitant polymorphism of KNaNbOF5 crystals. The second β-modification of the compound, crystallizing in the tetragonal crystal system is found for the first time: space group P4/nmm, a = 5.9352(2) Å, c =8.5487(5) Å, V = 301.14(2) Å3, Z = 2, R1 = 0.0095. Parameters of the orthorhombic noncentrosymmetric structure of the α-phase, previously described by Poeppelmeier et al. (J. Am. Chem. Soc., 129, 13963–13969 (2007)), are refined and a comparative analysis of both structures is performed. The structures are characterized by the complete ordering of oxygen and fluorine atoms, the Nb-O distance in the α-phase (1.738(1) Å) being noticeably longer than that in the β-phase (1.709(2) Å). In β-KNaNbOF5, alternating NbOF5 and NaOF5 octahedra share vertices, while in α-KNaNbOF5, they share both vertices and edges. The existence of the non-polar centrosymmetric β-modification of KNaNbOF5 cancels the assumption of the substantial contribution of potassium cations to the polar structure of α-KNaNbOF5.

Crystal and molecular structure of the complex of 2-(1-silatranylmethylthio)-4,5-benzo-1,3-thiazole with CoCl2 and MeCN

The crystal and molecular structure of the complex of 2-(1-silatranylmethylthio)-4,5-benzo-1,3-thiazole with CoCl2 and MeCN (I) is determined by single crystal X-ray diffraction. The geometry of the silatranylmethyl moiety in complex I is compared to the geometry of 1-(2′-benzthiazolylthiomethyl) silatrane. Molecular packing in the crystal is analyzed.

Orthorhombic aluminium oxyfluoride, AlOF.

Crystals of the title compound were extracted from the bulk of grown SrAlF(5) crystals as unexpected inclusions that were identified as the long sought after aluminium oxyfluoride. The structure of AlOF is built up from tetrahedral and octahedral polyhedra. Each tetrahedron is bisected by a mirror plane, with the Al atom and two vertex anions in the plane. All tetrahedral vertices are positions of competing oxide and fluoride ions and are shared with octahedra. These shared vertices belong to two octahedral edges which join the octahedra to form infinite zigzag chains. The chains are strung along twofold screw axes that run parallel to the unit-cell b axis. The remaining two octahedral vertices are occupied only by fluoride ions. A small deficiency in the occupation of the octahedral Al position was suggested by the refinement. However, the stoichiometry of the compound is AlOF within experimental uncertainty. The Al-F(O) distances are separated into three groups with average values of 1.652 (3) (tetrahedra), 1.800 (2) (octahedra) and 1.894 (2) A (octahedra). This structure differs widely from the reported tetragonal phase Al(1-x)O(1-3x)F(1+3x) (x = 0.0886) [Kutoglu (1992). Z. Kristallogr. 199, 197-201], which consists solely of octahedral structural units.

Structure and magnetism of copper-substituted cobalt ludwigite Co3O2BO3

Single crystals of Co3O2BO3 with partial (4%) substitution of Co by Cu ions were synthesized by the flux technique. X-ray diffraction and magnetic studies were carried out. The x-ray diffraction measurements show clearly that Cu preferentially occupies only one of the four nonequivalent crystallographic positions, the one with the smallest electric field gradient. The ferrimagnetic ordering near TN = 43 K and the high magnetic hardness in this magnetic phase are similar to those of Co3O2BO3. Copper substitution causes a small reduction in the effective magnetic moment.