Search results for "X-Ray"
showing 10 items of 4234 documents
Cyclometallation reactions in complexes of the type Rh(oq)(CO)[P(o-BrC6F4)Ph2]. The molecular structure of F4)Ph2] (oq = 8-hydroxyquinolinate)
1984
Cyclometallation occurs when a solution of the complex Rh(oq)(CO)(PCBr), (PCBr = 2-bromo-3,4,5,6-tetrafluorophenyldiphenylphosphine; oq = 8-hydroxyquinolinate) in toluene is refluxed, giving Rh(oq)2(PC) (PC = P(C6F4)(C6H5)2) and a dimeric compound, not yet completely characterized, formulated as Rh2Br(oq)(PCBr)2. Rh(oq)2(PC) was characterized by elemental analysis, by conductance measurements, and by 19F, 31P NMR and infrared spectroscopy. Its molecular structure was determined by single-crystal X-ray methods and refined by standard procedures to final agreement factors R and Rw of 0.067 and 0.060 for 5346 observed data. Lattice constants are 15.8494(6), 14.7188(5), 14.6675(5) A and β 96.93…
Crystal and molecular structure of the tris(1,10-phenanthroline)potassium salt of μ-hydridobis[pentacarbonylchromium(0)]
1984
Abstract The crystal and molecular structure of [K(phen)3][Cr2(CO)10(μ-H)] has been determined by X-ray diffraction. The compound crystallizes in the space group P 1 with a 11.884(4), b 13.968(4), c 15.612(6) A, α 112.6(1), β 99.7(1) and γ 106.2(1)° and Z = 2. The structure was refined to R = 0.066 and RW = 0.067 for 3692 counter data with I ⩾ 3σ(I). The complex anion [Cr2(CO)10(μ-H)] adopts a bent Cr-H-Cr configuration with the equatorial carbonyl groups of the two independent Cr(CO)5 moieties in an eclipsed configuration. The Cr⋯Cr distance is 3.394(3) A and the two CrH bonds are 1.74(7) and 1.71(7) A. The CrHCr bond angle is 159(3)°. In the dimeric complex cation [K(phen)3]2, located …
Synthesis and characterization of mono- and binuclear copper(II) complexes with 2,2′:6′,2″-terpyridine (terpy) and carboxylates: X-ray crystal struct…
1987
Abstract Perchlorate and hexafluorophosphate salts of monomeric [Cu(terpy)(OOCH)(OH2)]+ and dimeric [Cu(terpy)(OOCR)]22+ cations (terpy = 2,2′:6′,2″-terpyridine, R = CH3 or C2H5) have been synthesized and characterized by IR, electronic and ESR spectra, and analytical data. Spectroscopic results indicate a five-coordinate, close-to-square pyramidal geometry around the copper(II) ion. The half-field absorption in the ΔMs = 2 region of powdered X-band ESR spectra has been observed for the dimeric species. The crystal structure of [Cu(terpy)(OOCH)(OH2)](ClO4) has been determined by X-ray diffraction methods. The compound crystallizes in the space group P21/c with unit-cell dimensions: a = 7.34…
Synthesis of ruthenium(II) compounds with ortho-oxypyridinate ligands (hp). Crystal structure characterization of [Ru(η6-p-CH3C6H4CH(CH3)2)Cl(hp)]
1988
Abstract The reaction of [Ru(η6-p-cymene)Cl2]2 (p-cymene = p-CH3C6H4CH(CH3)2) with Nahp in THF yields [Ru(η6]-p-cymene)Cl(hp)] (1). The crystal structure of (1) has been determined by X-ray methods. (1) crystallizes in the space group Pbca, with a = 16.629(2), b = 10.201(3), c = 17.752(2) A. The compound contains one coordinated arene group, one chlorine and one hp group in a chelating coordination mode. The reaction of (1) with Aghp yields [Ru(η6-p-cymene)(hp)2] (2). The 13C NMR spectrum at - 70°C is consistent with a structure Ru(η6-p-cymene)(η2-hp)(η1-hp). At room temperature a rapid interconvertion between the two hp ligands occurs according to the observed 1H and 13C NMR spectra.
Crystal structure and electronic properties of bis(mepirizole) copper(II) perchlorate. Correlation between the electronic spectrum and CuN4 chromopho…
1985
The crystal structure of the title compound has been determined from single-crystal x-ray diffraction data. The crystals are tetragonal, space group P42212, withz=2 in a unit cell of dimensionsa=b=9.575(2),c=16.135(5) A. The structure was solved by the usual Patterson and Fourier techniques, and was refined by least-squares analysis to an R value of 0.057 for 545 observed reflexions. Two mepirizole molecules are arranged in a flattened tetrahedral manner (average Cu-N, 1.974 A) around Cu, and coordinated through N atoms. The dihedral angle between N-Cu-N planes of the two ligands is 53.6+°. This geometry seems to result from steric interaction between the ligands. The e.s.r. spectrum is axi…
Layer-by-layer deposited multilayer assemblies of polyelectrolytes and proteins: from ultrathin films to protein arrays
2008
We have recently introduced a new method of creating ultrathin films of polyelectrolytes based on the electrostatic attraction between opposite charges. Multilayer assemblies are adsorbed in a layer-by-layer fashion from aqueous solutions of the polymers. The total film thickness can easily be adjusted by varying the ionic strength of the solution. Here, we report on the temperature stability and the water content of the multilayer assemblies. Furthermore, we have extended our concept to the incorporation of protein layers into films of synthetic polyelectrolytes. The well established system biotin/streptavidin was used to construct such multilayers, also by biospecific recognition. Adsorpt…
Surface-Functionalized Latex Particles as Controlling Agents for the Mineralization of Zinc Oxide in Aqueous Medium
2005
Polystyrene latex particles modified at the surface with different hydrophilic functional groups were prepared by miniemulsion polymerization and used as controlling agents in the crystallization of zinc oxide from aqueous medium. The effects of the chemical nature of the surface functionalization and the latex concentration on the crystal growth, morphology, and crystalline structure of the resulting zinc oxide were analyzed. Micro- and submicrosized crystals with a broad variety of morphologies depending on the functionalization were obtained. Among the different latexes studied, the acrylic-acid-derived particles were shown to be a convenient system for further quantitative investigation…
ChemInform Abstract: tris-Pentasulfidorhodates(III). X-Ray Structure of (NH4)3(Rh(S5)3)(H2O)2.
1987
Abstract The crystal structure of the racemic dihydrated ammonium salt of the tris -pentasulfidorhodate(III) anion is compared with those of salts of the tris -pentasulfidoplatinate(IV) ion.
Tris-pentasulfidorhodates(III). X-ray structure of (NH4)3[Rh(S5)3](H2O)2
1987
Abstract The crystal structure of the racemic dihydrated ammonium salt of the tris -pentasulfidorhodate(III) anion is compared with those of salts of the tris -pentasulfidoplatinate(IV) ion.
Conformation of tert-butoxycarbonylglycyl-dehydroalanyl-glycine methyl ester in the crystalline state and calculated in the gas phase.
2006
tert-Butoxycarbonylglycyl-dehydroalanyl-glycine methyl ester (systematic name: methyl {2-[(tert-butoxycarbonylamino)acetamido]prop-2-enamido}acetate) (Boc0-Gly1-ΔAla2-Gly3-OMe), C13H21N3O6, has been structurally characterized by single-crystal X-ray diffraction and by density functional theory (DFT) calculations at the B3LYP/6–311+G** level. The peptide chain in both the solid-state and calculated structures adopts neither β nor γ turns. All amino acid residues in the tripeptide sequence are linked trans to each other. The bond lengths and valence angles of the amino acid units in the crystal structure and gas phase are comparable. However, the conformation of the third glycyl residue (…