Effect of crystal packing on the structures of polymeric metallocenes

The pressure dependencies of the crystal structures of the polymeric metallocenes lithium cyclopentadienide (LiCp) and potassium cyclopentadienide (KCp) have been determined by synchrotron X-ray powder diffraction. The decrease of the volume of LiCp by 34% up to a pressure of p = 12.2 GPa and of KCp by 23% at p = 5.3 GPa as well as the bulk moduli of K = 7.7 GPa for LiCp and 4.9 GPa for KCp indicate a high compressibility for these compounds. The crystal structures of KCp have been determined up to p = 3.9 GPa. An increase of the bend angle is found from 45 degrees at p = 0 GPa up to 51 degrees at p = 3.9 GPa. This variation is completely explained by a model invoking attractive K+ Cp- interaction and repulsive nonbonded carbon-carbon interactions. It is proposed that the bend angle in the polymeric alkali metal metallocenes is the result of the optimization of the crystal packing.     

The Crystal Structure of Disodium Phosphonate,Na2HPO3

Anhydrous disodium phosphonate, Na₂HPO₃, was prepared by dehydration of its pentahydrate. The crystal structure of Na₂HPO₃ was solved from high resolution X‐ray powder diffraction data (P2₁/n; Z = 4; a = 9.6987(1), b = 6.9795(1), c = 5.0561(1) Å, β = 92.37(1)°; V = 341.97(1) ų). The crystal structure consists of two types of sodium‐oxygen polyhedra, which are connected via common edges and vertices forming layers perpendicular to [100]. These Na(1)‐ and Na(2)‐layers are interlinked via common edges, forming in a 3D‐framework. The resulting topology is providing oxygen arrangements that please the coordinative requirement of phosphorus(III).     

Three-dimensional blow-up solutions of the Navier-Stokes equations

In this paper we extend the plane blow-up results of Grundy& McLaughlin (1997) to the three-dimensional Navier-Stokes equations.Using a solution structure originally due to Lin we first providenumerical evidence for the existence of blow-up solutions on- < x, z < , 0 y 1 with boundary conditions on y = 0and y = 1 involving derivatives of the velocity components.The formulation enables us to consider plane and radial flowas special cases. Various features of the computations are isolatedand are used to construct a formal asymptotic solution closeto blow-up. We show that the numerical and asymptotic analysesprovide a mutually consistent global picture which supportsthe conclusion that, for the family of problems we considerhere, blow-up in fact can take place in three dimensions butat an inverse linear rate rather than the faster inverse squareof the plane case.     

Long-term retention of ice-nucleating active Pseudomonas fluorescens by overwintering colorado potato beetles

Ice nucleating-active Pseudomonas fluorescens F264C was fed to Colorado potato beetles to determine bacterial retentioin in the beetle gut and its effect on the cold hardiness of this insect pest. The bacrterium was present in beetles recovered after overwintering in the field, seven months after their exposure to P. fluorescens. Retention was evident not only in the detection of the P. fluorescens ice nucleating gene, inaW, in bacterial cultures from beetle guts but also in the elevated supercooling points of some treated beetles.     

Sodium dithiophosphate(V): Crystal structure, sodium ionic conductivity and dismutation

Na₃PO₂S₂ was synthesized from the corresponding undecahydrate by freeze–drying. It dismutates at temperatures above 350 °C into Na₃PO₃S and Na₃POS₃. The crystal structure of Na₃PO₂S₂ was determined from X-ray powder diffraction data, and refined using the Rietveld technique (Pbca, a=17.5359(2) Å, b=11.3044(1) Å, c=5.8656(1) Å, R_F²=8.45%, R_p=4.80%, R_wp=6.79%). The baricenters of the PO₂S₂-tetrahedra are arranged in the sense of a hexagonal close packing. One of the P---O bonds of these tetrahedra is oriented parallel to the crystallographic c-axis with the POS₂-groups in an eclipsed mutual orientation. The crystal structure of Na₃PO₂S₂ displays a close relationship to the ones of Ca₃CrN₃ and Na₃POS₃. Above 330 °C, Na₃PO₂S₂ can be regarded as a fast ionic conductor (with σ>10⁻⁵ S cm⁻¹).     

Solvent-free methylthiomethyllithium [LiCH2SMe]infinity: solid state structure and thermal decomposition

Solvent-free [LiCH2SMe]infinity forms a layer structure consisting of four- (Li2C2), five- (Li2CS2), and six-membered (Li2C2S2) rings in the solid state; the compound violently explodes upon heating to T=160+/-5 degrees C under an argon atmosphere.