Reaction Of Yttrium Research Articles

Structural characteristics and ablative behavior of YF3 modified C/C-ZrC-SiC composites and their preparation by molten salt assisted reactive melt infiltration

In order to further improve the ablative resistance of C/C-ZrC-SiC composites, YF3 modified C/C-ZrC-SiC composites were prepared by molten salt assisted reactive melt infiltration, and the infiltration mechanism and ablative behavior of the composites were discussed. After fluorination, diffusion, adsorption and reaction of yttrium in ionic melt generated by K2ZrF6, YF3 was generated inside C/C-ZrC-SiC composites, which effectively seals the existing pores and cracks in C/C-ZrC-SiC material. YF3 modified C/C-ZrC-SiC composites can form yttrium oxide stabilized zirconia during the ablation process, and improve the ablation stability of the oxide layer compared with C/C-ZrC-SiC composites, the mass ablation rate and linear ablation rate of YF3 modified C/C-ZrC-SiC composites are reduced by 42.61% and 90.14% respectively.

Fluorine extraction from organofluorine molecules to make fluorinated clusters in yttrium MOFs.

A new rare earth based two-dimensional coordination network and a three-dimensional metal-organic framework (MOF) have been synthesized using bicinchoninic acid (BCA) and yttrium(iii) ions. Yttrium dimer nodes are formed in the absence of a modulator, resulting in a 2D layered coordination network (Y-BCA-2D). The presence of fluorinating agents, e.g., 2-fluorobenzoic acid (2-FBA), 2,6-difluorobenzoic acid (2,6-DFBA), and perfluorohexanoic acid (PFHxA) result in μ3-F bridged metal hexaclusters (Y6F8) that form a three-dimensional MOF (Y-BCA-3D). It was found that Y3+ can break highly stable C-F bonds in aromatic and aliphatic fluorinated compounds. Single-crystal X-ray diffraction (SC-XRD) shows the presence of fluorine in the metal cluster which was confirmed by energy dispersive X-ray spectroscopy (EDS). High resolution X-ray photoelectron spectroscopy (XPS) and 19F Nuclear Magnetic Resonance (NMR) also verify the presence of metal-fluorine bonds in the cluster. The Y-BCA-3D MOF selectively adsorbs CO2 but not N2.

Tetrahalocatecholate Rare Earth Complexes: Dinuclear Motifs with Intramolecular RE···XC(Ar) Interactions

The reaction of yttrium or cerium nitrate and tetrachloro- or tetrabromocatecholate (X4Cat2- with X = Cl or Br) has afforded the compounds: (Et3NH)2[{Y(Cl4Cat)(H2O)2}2(-Cl4Cat)2]‧2MeOH‧2H2O (1-Cl)...

Spectrophotometric Assay of Yttrium(III) with Alizarin Red S in the Presence of etyltrimethylammonium Bromide -Application to Water Samples

A simple, accurate and sensitive procedure for spectrophotometric determination of yttrium (III) in aqueous solution has been developed. The method is based on the reaction of yttrium (III) with alizarin red S (ARS) reagent in the presence of cetyltrimethylammonium bromide (CTAB) and triton-X-100 surfactants at pH 4.7 to form a red carmine complex which has maximum absorption at 520 nm. Beer's law is obeyed over the concentration range 2.5-75 µg yttrium (III) /20 ml, (i.e. ,0.125-3.73 ppm) with a determination coefficient of (0.9954) and molar absorptivity of 1.16×104 l.mol-1.cm-1. The limit of detection (LOD) and the limit of quantification (LOQ) are 0.1009 and 0.323 g.mL-1, respectively. Under optimum conditions, the stoichiometry of the reaction between yttrium (III), alizarin red S and CTAB is found to be 1:2:2, respectively. The recoveries are obtained in the range of 98.07 - 100.63% and the relative standard deviation is better than ±2.33%. The method has been successfully applied to the determination of yttrium(III) in natural waters

Spectrophotometric Determination of Yttrium with Pyrocatechol Violet Reagent – Application to Water

A simple and sensitive procedure for spectrophotometric determination of yttrium (III) in aqueous solution has been developed. The method is based on the reaction of yttrium with pyrocatechol violet at pH 7.6 to form a blue–violet complex which has maximum absorption at 595nm. Beer's law is obeyed over the concentration range 1-100 µg/25ml, (i.e., 0.04-4.0ppm) of yttrium with a molar absorptivity of 8.365×103 l.mol-1.cm-1. The accuracy (relative error) is (+0.33― -0.31%) and relative standard deviation is better than ±1.63%. The method has been successfully applied to the determination of yttrium in river and sea water .

Study on the complex-formation reaction of yttrium with para-methyl-chlorophosphonazo(CPApM)

Yttrium forms with CPApM a 1:2 α-complex instantaneously in acidic medium. At pH∼5 (buffer solution), the α-complex is transformed to a β-complex with an absorption peak at 755 nm after standing. The transformation reaction is a first-order reaction. The rate constant and the apparent activation energy were found to be 9.67 × 10−1 min−1 and 52.3 kJ·mol−1 respectively. The mechanism of the reaction shows that the β-complex (Y:CPApM=2:4) is formed by combining two molecules of α-complex with the liberation of one proton.

Reactions of Yttrium and Scandium Atoms with Acetylene: A Matrix Isolation Infrared Spectroscopic and Theoretical Study

Laser-ablated yttrium and scandium metal atoms have been codeposited at 4 K with acetylene in excess argon. Products, Y(C(2)H(2)), HYCCH, HScCCH(-), and HScScCCH(-), have been formed in the present experiments and characterized using infrared spectroscopy on the basis of the results of the isotopic shifts, mixed isotopic splitting patterns, stepwise annealing, the change of reagent concentration and laser energy, and the comparison with theoretical predictions. Density functional theory calculations have been performed on these molecules. The agreement between the experimental and calculated vibrational frequencies, relative absorption intensities, and isotopic shifts supports the identification of these molecules from the matrix infrared spectra. Plausible reaction mechanisms have been proposed to account for the formation of these molecules.

Infrared Spectra of Oxygen-Rich Yttrium and Lanthanum Dioxygen/Ozonide Complexes in Solid Argon

The reactions of yttrium and lanthanum atoms with O(2) have been reinvestigated using matrix isolation infrared spectroscopy and theoretical calculations. The ground-state yttrium and lanthanum atoms react with O(2) to produce the inserted yttrium and lanthanum dioxide molecules as the initial products. The yttrium dioxide molecule interacts spontaneously with additional O(2) molecules to form the oxygen-rich OY(eta(2)-O(3)) complex and possibly the (eta(2)-O(2))Y(eta(2)-O(3))(2) complexes upon sample annealing, which can be regarded as the side-on bonded yttrium monoxide ozonide complex and the superoxo yttrium bisozonide complex, respectively. Visible irradiation induces the isomerization of the OY(eta(2)-O(3)) complex to the superoxo yttrium peroxide Y(eta(2)-O(2))(2) isomer, in which both the superoxo and peroxo ligands are side-on bonded to the yttrium center. The lanthanum dioxide molecule reacts with additional O(2) molecules to form the lanthanum dioxide-dioxygen complex with planar C(2v) symmetry, which rearranges to the lanthanum monoxide ozonide complex, OLa(eta(2)-O(3)), under near-infrared excitation.

Matrix Isolation Infrared Spectroscopic and Density Functional Theory Studies on the Reactions of Yttrium and Lanthanum Hydrides with Dinitrogen

Laser-ablated yttrium and lanthanum hydrides have been codeposited at 4 K with dinitrogen in excess argon. Products, HY(N2), HYNN, H2YNN, HLaNN, and H2LaNN, have been formed in the present experiments and characterized by using infrared spectroscopy on the basis of the results of the isotopic shifts, mixed isotopic splitting patterns, stepwise annealing, and comparison with theoretical predictions. Density functional theory calculations have been performed on these molecules. The agreement between the experimental and calculated vibrational frequencies, relative absorption intensities, and isotopic shifts supports the identification of these molecules from the matrix infrared spectra. Plausible reaction mechanisms have been proposed for the formation of these molecules.

Infrared Spectroscopic and Density Functional Theory Studies on the Reactions of Yttrium and Lanthanum Atoms with Nitrous Oxide in Excess Argon

Reactions of laser-ablated Y and La atoms with N2O molecules in excess argon have been investigated using matrix-isolation infrared spectroscopy. Metal monoxide-dinitrogen complexes, OM(N2) (M = Y, La) and OYNN, have been formed during sample deposition and identified on the basis of isotopic shifts, mixed isotopic splitting patterns, and CCl4-doping experiments. The OYNN(+) and OLaNN(+) cation complexes appear during sample deposition and increase visibly upon broad-band irradiation (lambda > 250 nm) at the expense of the neutral metal monoxide-dinitrogen complexes. Density functional theory calculations have been performed on the products. The agreement between the experimental and calculated vibrational frequencies, relative absorption intensities, and isotopic shifts supports the identification of these species from the matrix infrared spectra. Furthermore, a plausible reaction mechanism for the formation of these products has been proposed.

Matrix Isolation Infrared Spectroscopic Studies and Density Functional Theory Calculations of the MNN, (MN)2 (M = Y and La), and Y3NN Molecules

The reactions of yttrium and lanthanum with dinitrogen were reinvestigated. Laser-ablated yttrium and lanthanum atoms were co-deposited at 4 K with dinitrogen in excess argon, and the low-temperature reactions of Y and La with N2 in solid argon were studied using infrared spectroscopy. The reaction products YNN, (YN)2, LaNN, and (LaN)2 were formed in the present experiments and characterized on the basis of 14N/15N isotopic shifts, mixed isotope splitting patterns, stepwise annealing, change of reagent concentration and laser energy, and comparison with theoretical predictions. Some assignments were made based on a previous report. Density functional theory calculations were performed on these systems to identify possible reaction products. The agreement between experimental and calculated vibrational frequencies, relative absorption intensities, and isotopic shifts of the MNN and (MN)2 (M = Y and La) molecules supports the identification of these molecules from the matrix infrared spectra. Plausible reaction mechanisms were proposed for the formation of these molecules along with tentative identification of the Y3NN molecule.

Matrix Isolation Infrared Spectroscopic and Density Functional Theory Studies on the Reactions of Yttrium and Lanthanum Hydrides with Carbon Monoxide

Laser-ablated yttrium and lanthanum hydrides have been co-deposited at 4 K with carbon monoxide in excess argon. Products, such as HYCO, (HY)2CO, HLaCO, HLa(CO)2, and H2LaCO, have been formed in the present experiments and characterized using infrared spectroscopy on the basis of the results of the isotopic shifts, mixed isotopic splitting patterns, stepwise annealing, the change of reagent concentration and laser energy, and the comparison with theoretical predictions. Density functional theory calculations have been performed on these molecules. The agreement between the experimental and calculated vibrational frequencies, relative absorption intensities, and isotopic shifts supports the identification of these molecules from the matrix infrared spectra. Plausible reaction mechanisms have been proposed to account for the formation of these molecules.

A computational study on the reaction of yttrium with ketene

The reaction of yttrium ( 2D) with ketene (H 2CCO) examined recently in crossed molecular beam experiments has been studied at B3LYP and CCSD (T) level. After the formations of different π-complexes with Y binding to C C O, C C and C O sites, respectively, several reaction channels are open. Two possible H-elimination pathways have been identified and they were found to correlate with singlet ground state and triplet excited state product, 1 YCHCO and 3 YCHCO, respectively. Three possible H 2-elimination pathways have been identified, and the calculation results indicate that the two concerted pathways can be competing processes at low energy, while the step-wise mechanism needs higher collision energy. The experimentally observed products YCCO were found to exist in two different forms (cyclic and linear). The calculated barrier of Y insertion into C C bond leading to the dominant product YCH 2 at low collision energy in CMB study is only 2 kcal/mol and the potential energy surface of this reaction is flat. In addition, the insertion of Y into C O bond was also identified, but this reaction is correlated to the product (vinylidene H 2CC) with excited state, agreeing with the fact that the formation of YO+H 2CC was not observed in experiment.

Solvation of Yttrium with Ammonia Revisited. Di-amide Formation in the Reaction of Yttrium with Ammonia

The reactivity of yttrium atoms toward ammonia is revisited using expanded density functional theory calculations. The new results reveal that absorption of NH3 on YNH is dissociative to form Y(NH2)2. The di-amide species can adsorb further NH3 molecules molecularly to form Y(NH2)2NH3 and Y(NH2)2(NH3)2. The calculations aimed to reveal the detail of the potential energy curves between the imide and the di-amide forms. The Y(NH2)2(NH3)x species are more stable than those of YNH(NH3)x by more than 20 kcal/mol.

Investigation of silicon diffusion into yttrium using x-ray photoelectron spectroscopy

The reactions of yttrium (Y) metal on silicon (Si) are investigated by x-ray photoelectron spectroscopy (XPS). Low-temperature annealing studies are performed to investigate the diffusion of Si. It is found that Si diffusion occurs even under low annealing temperatures of <300°C in an ultrahigh vacuum environment. This is attributed to the weakening of the Si–Si covalent bonds by metallic Y. XPS depth profiling of room-temperature-oxidized films revealed a possible oxygen-mediated pathway which allowed significant Si diffusion at room temperature for silicate formation.

Triamidotriazacyclononane complexes of group 3 metals. Synthesis and crystal structures.

Reaction of yttrium and lanthanide trichlorides (Ln = La, Eu, Yb) with 1 equiv of the trisodium salt of 1,4,7-tris(dimethylsilylaniline)-1,4,7-triazacyclononane (Na(3)[(SiMe(2)NPh)(3)-tacn](THF)(2)) gives good yields of the compounds [M[(SiMe(2)NPh)(3)-tacn]] (M = Y (1), Eu (3), Yb (4)) and [La[(SiMe(2)NPh)(3)-tacn](THF)] (2). Reduction of 3 with Na/Hg followed by recrystallization in the presence of diglyme yielded crystals of [Eu[(SiMe(2)NPh)(3)-tacn]][Na(diglyme)(2)] (5). Synthesis of the uranium(III) complex [U[(SiMe(2)NPh)(3)-tacn]] (6) is achieved by reaction of 1 equiv of Na(3)[(SiMe(2)NPh)(3)-tacn](THF)(2) with uranium triiodide. The U(IV) complexes, [U[(SiMe(2)NPh)(3)-tacn]X] (X = Cl (7); I (8)), were prepared via oxidation of 6 with benzyl chloride or I(2), but salt metathesis from UCl(4) provided a higher yield route for 7. The solid-state structures of 1-7 were determined by single-crystal X-ray diffraction. The ligand [(SiMe(2)NPh)(3)-tacn] generates a trigonal prismatic coordination environment for the metal center in the neutral complexes 1, 3, 4, and 6 and the ionic 5. In 2 the six nitrogen atoms of the ligand are in a trigonal prismatic configuration with the oxygen atom of the THF capping one of the triangular faces of the trigonal prism. In 7 the coordination geometry around the uranium atom is best described as bicapped trigonal bipyramidal.

Hydrofluoride Synthesis of Fluorides of Some Rare-Earth Elements

Thermal gravimetric, X-ray phase, IR spectroscopic, and chemical analyses were applied to study the reaction of yttrium and neodymium oxides with NH4HF2.

Reactions of Yttrium and Lanthanum Atoms with Nitrogen. Infrared Spectra of the Metal Nitrides and Dinitrogen Complexes in Solid Argon and Nitrogen

Laser-ablated Y and La atoms react with nitrogen to produce metal nitrides and dinitrogen complexes, whereas thermally evaporated Y and La atoms form only dinitrogen complexes. The ligated mononitride complexes (NN)xYN and (NN)xLaN at 771.6 and 761.7 cm-1 in solid nitrogen are identified from nitrogen-15 shifts. These complexes predict gas-phase fundamentals near 800 and 790 cm-1 respectively for YN and LaN. The (YN)2 and (LaN)2 molecules and dinitrogen complexes are also identified from nitrogen-15 shifts and result from the reaction of two metal atoms with a single dinitrogen molecule involving the Y(N2) and La(N2) intermediate species. The same saturated (YN)2(NN)x and (LaN)2(NN)x dinitrogen complexes are prepared on annealing solid argon containing 2% N2 and deposition in pure nitrogen. The growth of ligated (YN)2(NN)x and (LaN)2(NN)x on annealing suggests that this nitrogen fixation reaction involves little activation energy.

Synthesis, characterization and selected reactions of yttrium and yetterbium porphyrin complexes

Synthesis, characterization and selected reactions of yttrium and yetterbium porphyrin complexes

Gas-phase kinetics of neutral transition metal atoms: reactions of yttrium through molybdenum with alkanes and alkenes at 300 K

We survey the reactivity of ground-state, neutral transition metal atoms from the left-hand side of the 4d series (Y through Mo) with eight alkanes and alkenes. Effective bimolecular rate constants are measured in 0.5-0.8 Torr of He in a fast flow reactor at 300 K with laser-induced fluorescence detection. None of the four ground-state metal atoms reacts with linear alkanes. Mo reacts slowly and Y, Zr, and Nb react rapidly with alkenes. From the absence of a measureable pressure dependence of the rate constant over the limited He range of 0.5-0.8 Torr, we infer that bimolecular elimination chemistry occurs. We relate the pattern of reactivity to recent ab initio calculations of the geometry and binding energy of M-C 2 H 4 and H-M-C 2 H 3 for 4d-series transition metals