STUDIES ON ORGANOLANTHANIDE COMPLEXES .40. SYNTHESIS AND X-RAY STRUCTURE OF BIS (2-METHOXYETHYLCYCLOPENTADIENYL) YTTRIUM AND YTTERBIUM TETRAHYDROBORATES

New bis (2-methoxyethylcyclopentadienyl) yttrium and ytterbium tetrahydroborates (Ln = Y, 1; Yb, 2) have been synthesized in good yield by the reaction of bis (2-methoxyethylcyclopentadienyl) lanthanide chlorides (Ln = Y, Yb) with sodium borohydride in THF at room temperature. The title complexes were characterized by elemental analyses, MS, H-1 NMR and IR spectra. The crystal structures of 1 and 2 have been determined by X-ray diffraction. 1 crystallizes from THF-n-Hexane in space group Pna2(1) with unit cell parametert: a = 1.2390(3), b = 1.1339(2), c = 1.1919 (2) nm and V = 1.6745(6) nm3 with z = 4 for D(c) = 1.39 g.cm-3.The structure was solved by direct method and refined to final R = 0.061 (for 1730 observed reflections). The Space group of 2 is Pna2(1) with unit cell parameters: a = 1.2399(6), b = 1.1371(5), c = 1.1897(2) nm and V = 1.6773(1) nm3 with z = 4 for D(c) = 1.72 g.cm-3, R = 0.038 (for 2157 observed reflections). The X ray structures and IR reveal the bidentate yttrium and ytterbium tetrahydroborate complexes with the intramolecular coordination bonds between lanthanide metal and ligand oxygen atoms.

SYNTHESIS AND CHARACTERIZATION OF BINUCLEAR ORGANOLANTHANIDE COMPLEXES INVOLVING CYCLOPENTADIENYL AND N-PROPYLOXIDE LIGANDS - X-RAY CRYSTAL-STRUCTURE OF [(C5H5)2YB(MU-OCH2CH2CH3)]2

By the reaction of Cp3Ln (Cp = C5H5; Ln = Dy, Ho, Yb) with equimolar n-propyl alcohol in THF (tetrahydrofuran) at room temperature three new binuclear organolanthanide complexes, [CP2Ln(mu-OCH2CH2CH3)]2 (Ln = Dy, Ho, Yb), have been synthesized, as shown by X-ray single-crystal structure analysis for the complex [Cp2Yb(mu-OCH2CH2CH3)]2. All the complexes were characterized by elemental analysis, IR and MS spectra. The Yb2O2 unit is planar, and the ytterbium atom is coordinated by two Cp ring centroids and two oxygen atoms of two n-propyloxide ligands to form a distorted tetrahedral geometry. The average Yb-C (Cp) bond distance is 2.589(17) angstrom. The average Yb-O distance is 2.199(5) angstrom. The Yb-Yb separation [3.521(1) angstrom] indicates that no metal-metal interaction is present.

SYNTHESIS, THERMAL-STABILITY AND X-RAY CRYSTAL-STRUCTURE OF THE BIS(CYCLOPENTADIENYL)YTTERBIUM NAPHTHOXIDE DERIVATIVE (C5H5)2YB(OC10H7)(THF)

Cp3Yb (Cp = C5H5) reacts with a-naphthol (HNP) in THF to form Cp2Yb(NP)(THF) (1), which crystallizes in the space group P2(1)/n with unit cell dimensions a = 8.084(2), b = 15.996(6), c = 15.973(7) angstrom, beta = 98.95(3), V = 2040.3 angstrom and D(calc.) = 1.69 g cm-3 for Z = 4. Least-squares refinement based on 2242 observed reflections converged to a final R value of 0.081. The average Yb-C(Cp) distance is 2.60(2) angstrom and Yb-O(THF) and Yb-O(NP) distances are 2.30(1) and 2.06(1) angstrom, respectively. The title compound loses the coordinated THF molecule readily by heating under vacuum to give dimeric [Cp2Yb(NP)]2 (2), which undergoes disproportionation to give Cp3Yb and Yb(NP)3 on heating above 230-degrees-C.

STRUCTURE-ANALYSIS OF MOLTEN CACL2-KCL SYSTEM BY X-RAY-DIFFRACTION

Radial distribution function of CaCl2-KCl (1:2 mol) melt was measured by X-ray scattering of high temperature liquid. The nearest neighbour distances of Ca2+-Cl-, K+-Cl- and Cl--Cl- ionic pairs are 0.278, 0.306 and 0.380 nm, respectively, Discussion on the relation between structure and physicochemical properties in the melt was simply done in this paper.

SYNTHESIS AND X-RAY CRYSTAL-STRUCTURE OF [EU(ETA-6-C6ME6)(ALCL4)2]4 - THE 1ST CYCLOTETRAMERIC LANTHANIDE(II) COMPLEX WITH A NEUTRAL PI-LIGAND

The reaction of EuCl3, AlCl3 and C6Me6 in toluene gives the Eu(II) complex [Eu(eta-6-C6Me6)(AlCl4)2]4; X-ray crystal determination shows the molecule to be a cyclotetramer, in which the four Eu(C6Me6)AlCl4 units are connected via four groups of eta-2-AlCl4.

SYNTHESIS AND X-RAY CRYSTAL-STRUCTURE OF SM(C8H8)(2,4-C7H11).THF

SmCl3 reacts with K2C8H8 to yield the complex Sm(C8H8)Cl.2thf, which reacts with K(2,4-C7H11) (2,4-C7H11 = 2,4-dimethylcyclopentadienyl) to form Sm(C8H8)(2,4-C7H11).thf; the X-ray crystal structure of Sm(C8H8)(2,4-C7H11).thf shows that the 2,4-dimethylcyclopentadienyl has a 'U' conformation.

FACTOR-ANALYSIS APPLIED TO X-RAY-DIFFRACTION DIAGRAMS OF POLYMER BLENDS

The feasibility of applying the method of factor analysis to X-ray diffraction diagrams of binary blends of polypropylene and ethylene-propylene-diene terpolymer (PP/EPDM) was examined. The result of mathematical treatment was satisfactory. The number of scattering species and their concentrations in six kinds of PP/EPDM blends were determined. The separation of the spectral peaks of each species in the blends, contributing spectral intensities, was carried out.

CRYSTALLINITY OF UNIFORM OLIGO(OXYETHYLENE) MONO-N-ALKYL ETHERS STUDIED BY X-RAY-DIFFRACTION AND DIFFERENTIAL SCANNING CALORIMETRY

The crystallinity of two series of uniform oligo(oxyethylene) mono-n-alkyl ethers has been investigated: alpha-alkyl,omega-hydroxyoligo(oxyethylene)s, H(CH2)n(OCH2CH2)mOH, and alpha-alkyl,omega-methoxyoligo(oxyethylene)s, H(CH2)n(OCH2CH2)mOCH3. The hydroxy-ended oligomers formed bilayer crystals, and the methoxy-ended oligomers formed monolayer crystals. The helical oxyethylene blocks were oriented normal to the layer-crystal end-group plane, whilst the trans-planar alkyl blocks were generally tilted at an angle delta = 60-degrees. The melting temperature and enthalpy of fusion were higher for hydroxy-ended oligomers than for corresponding methoxy-ended oligomers.

SYNTHESIS AND X-RAY CRYSTAL-STRUCTURE OF A MONOPENTAMETHYLCYCLOPENTADIENYL DERIVATIVE OF GADOLINIUM (NA(MU-2-THF)[(C5ME5)GD(THF)]2(MU-2-CL)3(MU-3-CL)2)2.6THF

The reaction of GdCl3 with 1 equiv of NaC5Me5 generates a neutral complex C5Me5GdCl2(THF)3 and a novel complex {Na(mu-2-THF)[(C5Me5)Gd(THF)]2(mu-2-Cl)3(mu-3-Cl)2}2.6THF whixh recrystallizes from THF in triclinic, the space group P1BAR with unit cell dimentions of a 12.183(4), b 13.638(6), c 17.883(7) angstrom, alpha-110.38(3), beta-94.04(3), gamma-99.44(3)-degrees, V 2721.20 angstrom-3 and D(calc) 1.43 g cm-3 for Z = 1. Least-squares refinement of 2170 observed reflections led to a final R value of 0.047. The title complex consists of two Na(mu-2-THF)[(C5Me5)Gd(THF)]2(mu-3-Cl)3(mu-3-Cl)2 units bridged together via two mu-2-THF to Na coordination. Each Gd ion is surrounded by one C5Me5 ligand, two mu-3-Cl, two mu-2-Cl and one THF in a distorted octahedral arrangement with average Gd-C(ring) 2.686(33), Gd-mu-2-Cl 2.724(7), Gd-mu-3-Cl 2.832(8) and Gd-O 2.407(11) angstrom. The sodium ion coordinates to two bridging THF, two mu-2-Cl and two mu-3-Cl to form a distorted octahedron with average Na-mu-2-O, Na-mu-2-Cl and Na-mu-3-Cl of 2.411(21), 2.807(15) and 2.845(12) angstrom, respectively.

The complete mitochondrial genomes of the whistling duck (Dendrocygna javanica) and black swan (Cygnus atratus): dating evolutionary divergence in Galloanserae

Galloanserae is an ancient and diverse avian group, for which comprehensive molecular evidence relevant to phylogenetic analysis in the context of molecular chronology is lacking. In this study, we present two additional mitochondrial genome sequences of Galloanserae (the whistling duck, Dendrocygna javanica, and the black swan, Cygnus atratus) to broaden the scope of molecular phylogenetic reconstruction. The lengths of the whistling duck's and black swan's mitochondrial genomes are 16,753 and 16,748 bases, respectively. Phylogenetic analyses suggest that Dendrocygna is more likely to be in a basal position of the branch consisting of Anatinae and Anserinae, an affiliation that does not conform to its traditional classification. Bayesian approaches were employed to provide a rough timescale for Galloanserae evolution. In general, a narrow range of 95% confidence intervals gave younger estimates than those based on limited genes and estimated that at least two lineages originated before the Coniacian epoch around 90 MYA, well before the Cretaceous-Tertiary boundary. In addition, these results, which were compatible with estimates from fossil evidence, also imply that the origin of numerous genera in Anseriformes took place in the late Oligocene to early Miocene. Taken together, the results presented here provide a working framework for future research on Galloanserae evolution, and they underline the utility of whole mitochondrial genome sequences for the resolution of deep divergence.

Improvement of different source function expressions in SWAN model for the Bohai Sea

The simulating wave nearshore (SWAN) wave model has been widely used in coastal areas, lakes and estuaries. However, we found a poor agreement between modeling results and measurements in analyzing the chosen four typical cases when we used the default parameters of the source function formulas of the SWAN to make wave simulation for the Bohai Sea. Also, it was found that at the same wind process the simulated results of two wind generation expressions (Komen, Janssen) demonstrated a large difference. Further study showed that the proportionality coefficient alpha in linear growth term of wave growth source function plays an unperceived role in the process of wave development. Based on experiments and analysis, we thought that the coefficient alpha should change rather than be a constant. Therefore, the coefficient alpha changing with the variation of friction velocity U (*) was introduced into the linear growth term of wave growth source function. Four weather processes were adopted to validate the improvement in the linear growth term. The results from the improved coefficient alpha agree much better with the measurements than those from the default constant coefficient alpha. Furthermore, the large differences of results between Komen wind generation expression and Janssen wind generation expression were eliminated. We also experimented with the four weather processes to test the new white-capping mechanisms based on the cumulative steepness method. It was found that the parameters of the new white-capping mechanisms are not suitable for the Bohai Sea, but Alkyon's white-capping mechanisms can be applicable to the Bohai Sea after amendments, demonstrating that this improvement of parameter alpha can improve the simulated results of the Bohai Sea.

In situ high temperature X-ray diffraction studies of mixed ionic and electronic conducting perovskite-type membranes

Phase structure and stability of three typical mixed ionic and electronic conducting perovskite-type membranes, SrCo0.8Fe0.2O3-delta (SCF), Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) and BaCo0.4Fe0.4Zr0.2O3-delta (BCFZ) were studied by in situ high temperature X-ray diffraction at temperatures from 303 to 1273 K and under different atmospheres (air, 2% O-2 in Ar and pure Ar) at 1173 K. By analyzing their lattice parameters the thermal expansion coefficients (TECs) of BSCF, SCF and BCZF are obtained to be 11.5 x 10(-6) K-1, 17.9 x 10(-6) K-1 and 10.3 x 10(-6) K-1, respectively. A relationship between phase stability and TEC was proposed: the higher is the TEC, the lower is the operation stability of the perovskite materials. (C) 2005 Elsevier B.V. All rights reserved.