Structure of a thionucleoside: 5'-deoxy-5',6-epithio-5,6-dihydro-2',3'-O-isopropylidene-3-methyluridine

C13HlsN205 S, M r = 314.35, orthorhombic, P212121 with a = 39.526 (4), b = 6.607 (2), c = 5.661 (2) A, Z = 4, V = 1478.36 A 3, D c = 1.412 Mg m -3, Cu Ka radiation. Final R = 0.073 for 1154 observed counter reflections. The sulphur atom is in a pseudo-equatorial position with respect to the dihydrouracil ring. The sugar pucker is predominantly O(l')-exo unlike the C(3')-exo,C(4')-endo observed for 2',3'-O-isopropylideneuridine (ISPU). The fivemembered dioxolane ring has C(7) displaced by 0.497 (7)A from the best plane through atoms 0(2'), C(2'), C(3'), 0(3'), in contrast to ISPU where 0(3') shows the maximum deviation.

Zeeman effect of chlorine nuclear quadrupole resonance and hydrogen bonding in 2,6-, 2,5- and 3,5-dichlorophenols

The Zeeman effect of chlorine nuclear quadrupole resonance in polycrystalline samples of 2,6-, 2,5 and 3,5-dichlorophenol has been investigated at room temperature in order to study the effect of hydrogen bonding on the electric field gradient asymmetry parameter n. While the two n.q.r. lines in 3,5-dichlorophenol gave an asymmetry parameter of 10%, those in 2,6- and 2,5-dichlorophenol gave different values of n for the two chlorines. The chlorine atom which is ortho to the OH group and involved in hydrogen bonding (i.e., corresponding to the low frequency line) gave an asymmetry parameter of 0.21 in 2,6-dichlorophenol and 0.17 in 2,5-dichlorophenol while the other chlorine (i.e., corresponding to the high frequency line) gave a lower value of 0.12 in 2,6-dichlorophenol and 0.11 in 2,5-dichlorophenol. These values of n are discussed in terms of hydrogen bonding and bond parameters.

4,6,8,10,16-Penta- and 4,6,8,10,16,18-hexamethyldocosanes from the cane beetle Antitrogus parvulus - Cuticular hydrocarbons with unprecedented structure and stereochemistry

The major cuticular hydrocarbons from the cane beetle species Antitrogus parvulus were deduced to be 4,6,8,10,16,18-hexa- and 4,6,8,10,16- pentamethyldocosanes 2 and 3, respectively. Isomers of 2,4,6,8-tetramethylundecanal 27, 36, and 37, derived from 2,4,6-trimethylphenol, were coupled with the phosphoranes 28 and 29 to furnish alkenes and, by reduction, diastereomers of 2 and 3. Chromatographic and spectroscopic comparisons confirmed 2 as either 6a or 6b and 3 as either 34a or 34b.

ESR Studies of Phase Transitions in Double Propionates: Dicalcium Barium Propionate Ca2Ba(C2H5COO)6

Single crystal [(111) and (100) planes], and powder ESR of Mn2+ (substituting for Ca2+) in Ca2Ba(C2H5COO)6 in the temperature range 220°C to -160°C shows (i) a doubling of both the physically and chemically inequivalent sites, and a change in the magnitude (150 G at -6°C to 170 G at -8°C) as well as the orientation of the D tensor across the -6°C transition and (ii) an inflection point in the D vs T plot across the -75°C transition. The oxygen octahedra around the Ca2+ sites are inferred to undergo alternate rotations, showing the participation of the carboxyl oxygens in the -6°C transition. A relation of the type D=D0(1+αT+βT2) seems to fit the D variation satisfactorily.

Structure of 7-methyl-1(2)a,1(6)a,3(4)a-trihomocubane-1(6)a,3(4)a-dione,star-c12h12o2- a case of enantiomeric and rotational disorder

M r = 188.22, monoclinic, P21/n, a = 6.219 (2), b= 10.508 (2), c=7.339 (1)A, t= 107.64 (2) °, V= 457 ,/k 3, Z = 2, D m - - 1.360 (3), D x = 1.366 (2)Mgm -3, ~,(MoKa) = 0.7107/~, #= 0.053 mm -I, F(000) = 200, T= 293 K. Final R = 5.8% for 614 significant reflections. The molecule, which does not possess a centre of symmetry, occupies a crystallographic centre of symmetry because of the statistical enantiomeric and rotational disorder. Latticeenergy calculations, based on van der Waals attractive and repulsive potentials, clearly show minima at the observed disordered positions.

Stabilization of the Alleged 'Bishomoaromatic' Bicyclo[3.2.l]octa-2,6-dienyl Anion by Counterion Interactions and by Hyperconjugation

Hyperconjugation and inductive effects, rather than homoaromaticity, are responsible for the stabilization of the title anion in the gas phase; interaction of the double bond with the Li+ gegenion in the endo geometry contributes additionally in solution.

Synthesis, characterization and X-ray structure of hexahydrazinium diuranyl pentaoxalate dihydrate, (N2H5)6(UO2)2(C2O4)5·2H2O

A new hydrazinium uranyl oxalate complex (N2H5)6[(UO2)2(C2O4)5]·2H2O has been prepared and characterized by chemical analysis, infrared, visible spectra and TG-DTA. The single crystal X-ray structure of the complex shows the presence of discrete N2H5+ cations, water molecules and [(UO2)2(C2O4)5]6− anions. In the anion, the linear uranyl groups are coordinated by two chelating bidentate oxalates and one bridging oxalate which lies on the center of symmetry between the two uranyl groups. The coordination polyhedron around each uranium atom is approximately a pentagonal bipyramid.

Temperature dependence of 35Cl NQR in 2,6-dichloropyridine

Chlorine NQR in 2,6-dichloropyridine has been investigated in the temperature range 77 K to room temperature and a single resonance line has been observed throughout. Using this data, torsional frequencies of the molecule have been evaluated on the basis of both the Bayer theory and the modified Bayer theory incorporating Tatsuzaki correction.

Achievements in forest tree improvement in Australia and New Zealand 6: Genetic improvement and conservation of Araucaria cunninghamii in Queensland

Araucaria cunninghamii (hoop pine) typically occurs as an emergent tree over subtropical and tropical rainforests, in a discontinuous distribution that extends from West Irian Jaya at about 0°30'S, through the highlands of Indonesian New Guinea and Papua New Guinea, along the east coast of Australia from 11°39'S in Queensland to 30°35'S in northern New South Wales. Plantations established in Queensland since the 1920s now total about 44000 ha, and constitute the primary source for the continuing supply of hoop pine quality timber and pulpwood, with a sustainable harvest exceeding 440 000 m3 y-1. Establishment of these managed plantations allowed logging of all native forests of Araucaria species (hoop pine and bunya pine, A. bidwillii) on state-owned lands to cease in the late 1980s, and the preservation of large areas of araucarian forest types within a system of state-owned and managed reserves. The successful plantation program with this species has been strongly supported by genetic improvement activities since the late 1940s - through knowledge of provenance variation and reproductive biology, the provision of reliable sources of improved seed, and the capture of substantial genetic gains in traits of economic importance (for example growth, stem straightness, internode length and spiral grain). As such, hoop pine is one of the few tropical tree species that, for more than half a century, has been the subject of continuous genetic improvement. The history of commercialisation and genetic improvement of hoop pine provides an excellent example of the dual economic and conservation benefits that may be obtained in tropical tree species through the integration of gene conservation and genetic improvement with commercial plantation development. This paper outlines the natural distribution and reproductive biology of hoop pine, describes the major achievements of the genetic improvement program in Queensland over the past 50+ y, summarises current understanding of the genetic variation and control of key selection traits, and outlines the means by which genetic diversity in the species is being conserved.

4-(4-Methoxyphenyl)-1-phenylpyridine-2,6(1H,3H)-dione

In the title compound, C18H15NO3, the pyridine-2,6-dione ring adopts an envelope conformation. The phenyl ring lies approximately perpendicular to the mean plane of the pyridine-2,6-dione ring [dihedral angle =81.5 (1)degrees], while the methoxyphenyl ring is tilted to the same plane by a dihedral angle of 34.8 (1)degrees. Intermolecular C-H center dot center dot center dot O interactions link the molecules into chains along [100].

An infrared spectroscopic study of the incommensurate transitions and related phase changes in K2Pb[Cu(NO2)6] and [N(CH3)4]2MX4 (M = Mn, Co, Cu or Zn and X = Cl or Br)

K2Pb[Cu(NO2)6] and [N(CH3)4]2MX4 (M = Mn, Co, Cu or Zn and X = Cl or Br) undergo phase transitions which involve incommensurate phases. The transitions have been investigated by examining the changes in the NO2 and CH3 vibration bands in the i.r. spectra. Splitting and broadening of some of the bands across the incommensurate transitions are discussed in the context of geometrical restrictions in the incommensurate phases. The phase transitions have also been characterized using differential scanning calorimetry.

Evaluation Of Diffusion-Coefficient And Ionic Mobility In (Nh4)4fe(Cn)6.1.5 H2o

The diffusion coefficient, D, and the ionic mobility, μ, in the protonic conductor ammonium ferrocyanide hydrate have been determined by the isothermal transient ionic current method. D is also determined from the time dependence of the build up of potential across the samples and theretical expressions describing this build up in terms of double exponential dependence on time are obtained. The values obtained are D=3.875×10−11m2s−1 and μ=1.65×10−9 m2V−1s−1.

Structure of (6S,13bR)-1,2,3,5,6,13b-hexahydro-6-isopropyl-8H-pyrrolo[1',2':1,2]pyrazino[3,4,-b]quinazoline-5,8-dione

C17H19N302, monoclinic, P21, a = 5.382 (1), b = 17.534(4), c = 8.198(1)/L ,8 = 100.46(1) °, Z= 2, d,, = 1.323, dc= 1.299 Mg m-3, F(000) = 316, /~(Cu .Ka) = 0.618 mm -1. R = 0.052 for 1284 significant reflections. The proline-containing cispeptide unit which forms part of a six-membered ring deviates from perfect planarity. The torsion angle about the peptide bond is 3.0 (5) ° and the peptide bond length is 1.313 (5)A. The conformation of the proline ring is Cs-Cf~-endo. The crystal structure is stabilized by C-H... O interactions.

High-Pressure Nmr And Compressibility Evidence For A Phase-Transition In The Protonic Conductor (NH4)4Fe(CN)6.1.5H2o

1H NMR at high hydrostatic pressures and compressibility studies show that the protonic conductor (NH4)4Fe(CN)6·1.5H2O undergoes a phase transition around 0.45 GPa. The transition is characterized by a large hysteresis. From the NMR studies, an activation volume of 6% is obtained below the phase transition, indicating the dominance of Frenkel defects.