Chemical reactivities of the cation and anion of M@C82 (M = Y, La, and Ce)

The chemical reduction and oxidation of M@C82 (M = Y, La, and Ce) afford the corresponding anion and cation, respectively, which show unique and interesting chemical reactivities. It is found that the successful reversible gain or loss of electrons by ionization is useful for controlling the stability and reactivity of M@C82 toward both nucleophiles and electrophiles.     

ESR spectra of products of oxidation of endometallofullerenes M@C82 (M = Y,La, Ce,Gd)

The ESR spectra of the products of oxidation of solutions and powders of Y@C₈₂ and La@C₈₂ with fuming sulfuric acid were studied. Based on the oxidation conditions and the sequence of spectral patterns, the spectra were attributed to the radical cations M@C₈₂ ⁿ⁺ (n = 2, 4), dimers M³⁺ ₂@C₁₆₄ ⁺, and polyendometallofullerenes.     

The Unanticipated Dimerization of Ce@C2v(9)‐C82 upon Co‐crystallization with Ni(octaethylporphyrin) and Comparison with Monomeric M@C2v(9)‐C82 (M = La,Sc, and Y)

We report that Ce@C_2v(9)‐C₈₂ forms a centrosymmetric dimer when co‐crystallized with Ni(OEP) (OEP = octaethylporphyrin dianion). The crystal structure of {Ce@C_2v(9)‐C₈₂}₂?2[Ni(OEP)]?4 C₆H₆ shows that a new C?C bond with a bond length of 1.605(5) Å connects the two cages. The high spin density of the singly occupied molecular orbital (SOMO) on the cage and the pyramidalization of the cage are factors that favor dimerization. In contrast, the treatment of Ni(OEP) with M@C_2v(9)‐C₈₂ (M = La, Sc, and Y) results in crystallization of monomeric endohedral fullerenes. A systematic comparison of the X‐ray structures of M@C_2v(9)‐C₈₂ (M = Sc, Y, La, Ce, Gd, Yb, and Sm) reveals that the major metal site in each case is located at an off‐center position adjacent to a hexagonal ring along the C₂ axis of the C_2v(9)‐C₈₂ cage. DFT calculations at the M06‐2X level revealed that the positions of the metal centers in these metallofullerenes M@C_2v(9)‐C₈₂ (M = Sc, Y, and Ce), as determined by single‐crystal X‐ray structure studies, correspond to an energy minimum for each compound.     

Synthesis and structural characterization of monomeric heterobimetallic oxides with a GeII-O-M skeleton (M = Yb, Y)

The germanium hydroxide complexes LGe(mu-O)M(THF)Cp2 (M = Yb, 1; Y, 2; L = HC[C(Me)N(Ar)]2; Ar = 2,6-iPr2C6H3) were prepared by the reaction of LGeOH with Cp3M (M = Yb, Y) in THF at ambient temperature with the elimination of HCp. 1 and 2 are pale-yellow solids. Both compounds crystallize isotypically as monomers in a triclinic space group P (pseudo-merohedrally twinned, two independent molecules) and were found to be stable in the solid state and in solution at room temperature. The six-membered C3N2Ge rings in 1 and 2 display a boat conformation with the germanium and the gamma-C out-of-plane. The Ge-O-M skeleton exhibits a bent arrangement (angles 151-154 degrees ). The 1H NMR investigation of 2 confirmed that the solid-state structure is also found in solution.     

Mass-analyzed threshold ionization and structural isomers of M(3)O(4) (M = Sc, Y, and La)

M(3)O(4) (M = Sc, Y, and La) were produced in a pulsed laser-vaporization molecular beam source and studied by mass-analyzed threshold ionization (MATI) spectroscopy and electronic structure calculations. Adiabatic ionization energies (AIEs) of the neutral clusters and vibrational frequencies of the cations were measured accurately for the first time from the MATI spectra. Five possible structural isomers of M(3)O(4) were considered in the calculations and spectral analysis. A cage-like structure in C(3v) point group was identified as the most stable one. The structure is formed by fusing three M(2)O(2) fragments together, each sharing two O-M bonds with others. The ground electronic state of the neutral clusters is (2)A(1) with the unpaired electron being largely a metal-based s character. Ionization of the (2)A(1) state yields a (1)A(1) ion state in a similar geometry to the neutral cluster. The AIEs of the clusters are 4.4556 (6), 4.0586(6), and 3.4750(6) eV for M = Sc, Y, and La, respectively. The observed vibrational modes of the cations include metal-oxygen stretching, metal triangle breathing, and oxygen-metal-oxygen rocking in the frequency range of 200-800 cm(-1).     

Reactions of laser-ablated La and Y atoms with CO: matrix infrared spectra and DFT calculations of the M(CO)x and MCO+ (M = La, Y; x = 1-4) molecules

Reactions of laser-ablated lanthanum and yttrium atoms with carbon monoxide molecules in solid neon have been investigated using matrix-isolation infrared spectroscopy. The M(CO)x and MCO+ (M = La, Y; x = 1-4) molecules have been formed and identified on the basis of isotopic shifts, mixed isotopic splitting patterns, and CCl4-doping experiments. Density functional theory calculations have been performed on these lanthanum and yttrium carbonyls. The agreement between the experimental and calculated vibrational frequencies, relative absorption intensities, and isotopic shifts substantiates the identification of these carbonyls from the matrix infrared spectrum. The present study reveals that the C-O stretching vibrational frequencies of MCO+ decrease from Sc to La, which indicates an increasing in metal d orbital --> CO pi* back-donation in this series.     

New binary systems Mg-M-O (M=Y, La, Ce): Synthesis and physico-chemical characterization

New binary oxide Mg-M-O (M=Y, La, Ce) systems are obtained by co-precipitation and characterized by adsorption methods, X-ray diffraction method (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy of adsorbed probe molecules (CO and CDCl₃). It is shown that Mg-Y-O systems after calcination at 450-750 °C represent the physical mixtures of MgO and Y₂O₃, while the components of Mg-La(Ce)-O systems interact to form La₂MgO_x and (Ce,Mg)O₂ solid solutions, respectively. From XPS data, the surface of the binary systems is enriched with lanthanide ions. Addition of ≈5 mol% M₂O₃ to MgO results in an increase in concentrations of strong and weak Lewis acidic sites, the content of the latter being much higher and changing in the series: MgO<Mg-Ce-O<Mg-La-O<Mg-Y-O. At the same time basic sites become stronger in the binary systems but their total content decreases in comparison to that in individual MgO. Mg-M-O samples containing ≈5 mol% M₂O₃ are highly-dispersed and characterized by bimodal porous texture.     

Cation deficient layered Ruddlesden-Popper-related oxysulfides La2LnMS2O5 (Ln=La, Y; M=Nb, Ta)

The structures of the new oxysulfide Ruddlesden-Popper phases La2LnMS2O5 (Ln=La, Y; M=Nb, Ta) are reported together with an iodide-containing variant: La3-xNb1+xS2O5I2x (0相似文献   

Infrared spectra and density functional calculations for M(OH)(2,3) and HOMO molecules and M(OH)2+ cations (M = Y, La)

Reactions of laser-ablated Y and La atoms with H2O2 gives the M(OH)2 and M(OH)3 molecules and the HOMO dehydration product, and the cation M(OH)2+ in solid argon. Density functional calculations show that the dihydroxide molecules and cations are bent at the metal center, and the symmetric and antisymmetric O-H stretching modes are both observed in the infrared spectra. The trihydroxide molecules have calculated C(3h) structures characterized by strong antisymmetric O-H and M-O stretching modes. Mulliken charges increase for all product molecules going down the Group 3 family and increase as one, two, and three OH ligands are bonded to the metal center. Evidence is also presented for the Y(OH)4- anion.     

Synthesis and Thermal Decomposition Mechanism of Rare Earth （RE=La, Y, Gd） Salicylates

The rare earth (RE=La, Y, Gd) salicylates were synthesized by the rheological phase reaction method. The complexes were characterized by elemental analysis, infrared spectra (IR), X-ray powder diffraction (XRD) and thermal gravity analysis (TG). They can be represented by general formula RE(HSal)3 (RE=La, Y, Gd; HSal=C6Ha(OH)COO). The crystals of them are monoclinic and have layered structure. The mechanism of thermal decomposition of rare earth salicylates was studied by using TG, DTA, IR and gas chromatography-mass spectrometry (GC-MS). The thermal decomposition of the rare earth salicylates in nitrogen gas proceeded in three stages: firstly, they were decomposed to form RE2(Sal)3 (Sal=C6H4OCOO) and salicylic acid; then, RE2(Sal)3 were decomposed further to form RE2O(CO3)2 and some organic compounds; finally, RE2O(CO3)2 were decomposed to form rare earth metal oxides (RE2O3) and carbon dioxide. The organic compounds obtained from the second step of the reaction are mainly dibenzofuran, xanthenone, 6H-benzo[c]chromen-6-one, 6-phenyl-6H-benzo[c]chromene, and 1,3-diphenyl-1, 3-dihydro-2-benzofuran.     

多孔纳米Ce-M-O(M=Pr,La)粉末的微波诱导燃烧合成及其表征

使用Ce(NO₃)₃•6H₂O, Pr(NO₃)₃•6H₂O, La(NO₃)₃•6H₂O, 尿素为原料, 利用微波引诱燃烧法合成了多孔纳米Ce-M-O (M＝Pr, La)固溶体. 使用XRD, X光电子能谱仪(XPS), Raman光谱仪, 红外光谱仪(FT-IR), 透射电镜(TEM), 场发射扫描电镜(FE-SEM)等仪器对纳米粉体进行了表征. XRD分析显示Ce-M-O粉体的粒径在20～50 nm之间, 且所有样品均具有萤石结构. XPS证明在Ce-Pr-O固溶体中Pr以＋3和＋4两种形式存在. Raman光谱表明随着M^3＋的掺杂, 在CeO₂晶格中产生氧缺陷, 且缺陷浓度随掺杂量增加不断提高. 红外光谱证明Ce—O键的吸收峰在1400 cm^－1左右, 且由于M^3＋的掺杂在2346 cm^－1的吸收峰消失. TEM照片说明样品具有类盘状的网络纳米微晶结构. 扫描图像说明产物具有多孔的外貌特征, 且孔径分布在2～40 nm之间.     

Synthesis and characterization of bis-isonitrile complexes Cp2M(CNR)2 (M = Ti,Zr; R = 2,6-dimethylphenyl)

Bis-isonitrile complexes Cp₂M(CNR)₂ (M  Ti, Zr), where RNC is the sterically hindered 2,6-dimethylphenyl isonitrile, can be prepared in high yield by reduction of Cp₂MCl₂ with magnesium in THF solution in the presence of the isonitrile. ¹H NMR spectroscopy reveals that with the titanium complex dissociation of the isonitrile ligands takes place in solution.     

Two-dimensional hopping motion of encapsulated La atoms in silylated La(2)@C(80)

The (139)La NMR study of the exohedrally functionalized derivatives of La(2)@C(80) metallofullerene, La(2)@C(80)(Ar(2)Si)(2)CH(2) (: Ar = Mes, Mes = mesityl, : Ar = Dep, Dep = 2,6-diethylphenyl), reveal that the two La atoms hop between two sites along the equator of the C(80) cage.     

Electronic states and pseudo Jahn-Teller distortion of heavy metal-monobenzene complexes: M(C6H6) (M = Y, La, and Lu)

Monobenzene complexes of yttrium (Y), lanthanum (La), and lutetium (Lu), M(C(6)H(6)) (M = Y, La, and Lu), were prepared in a laser-vaporization supersonic molecular beam source and studied by pulsed-field ionization zero electron kinetic energy (ZEKE) spectroscopy and ab initio calculations. The calculations included the second-order perturbation, the coupled cluster with single, double, and perturbative triple excitation, and the complete active space self-consistent field methods. Adiabatic ionization energies and metal-benzene stretching frequencies of these complexes were measured for the first time from the ZEKE spectra. Electronic states of the neutral and ion complexes and benzene ring deformation were determined by combining the spectroscopic measurements with the theoretical calculations. The ionization energies of M(C(6)H(6)) are 5.0908 (6), 4.5651 (6), and 5.5106 (6) eV, and the metal-ligand stretching frequencies of [M(C(6)H(6))](+) are 328, 295, and 270 cm(-1) for M = Y, La, and Lu, respectively. The ground states of M(C(6)H(6)) and [M(C(6)H(6))](+) are (2)A(1) and (1)A(1), respectively, and their molecular structures are in C(2v) point group with a bent benzene ring. The deformation of the benzene ring upon metal coordination is caused by the pseudo Jahn-Teller interaction of (1(2)E(2)+1(2)A(1)+2(2)E(2)) e(2) at C(6v) symmetry. In addition, the study shows that spectroscopic behaviors of Y(C(6)H(6)) and La(C(6)H(6)) are similar to each other, but different from that of Lu(C(6)H(6)).     

La2M2O7(M=Ti,Zr)多晶粉末的低温水热合成及表征

低温水热合成是水热化学一个活跃的研究方向,在氧化物粉末的合成方面具有潜在的应用价值.La2M2O7(M=Ti,Zr)陶瓷材料的优良特性使其多晶粉末的合成倍受关注[1,2].     

New Y(La)-M-O Binary Systems (M = Ca,Sr, or Ba): Synthesis,Physicochemical Characterization,and Application As the Supports of Ruthenium Catalysts for Ammonia Synthesis

The effect of the nature of the alkaline-earth metal on the phase composition and specific surface area of new Y(La)-M-O binary oxide compositions (M = Ca, Sr, or Ba) prepared by coprecipitation was studied. These systems were found to contain mixed compounds (M₂Y₂O₅, MY₂O₄, and MLa₂O₄), which are different in thermal stability, in addition to individual La₂O₃ or Y₂O₃ phases. The Y(La)-M-O compositions calcined at 450°C were characterized by a more developed specific surface area, as compared with that of individual La₂O₃ or Y₂O₃. An increase in the calcination temperature to 650°C was accompanied by a decrease in the specific surface area of binary compositions. Catalysts prepared by supporting K₂[Ru₄(CO)₁₃] onto the Y(La)-M-O systems were active in ammonia synthesis at 250-400°C and atmospheric pressure. The most active of these catalysts, K₂[Ru₄(CO)₁₃]/Y-Ba-O, provided a higher yield of NH₃ at 250-300°C than analogous catalysts prepared with the use of well-known supports (Sibunit, CFC-1, and C/MgO).     

微波合成掺杂LiMxMn2O4(M=La,Nd,Y)的电化学性能

稀土;微波化学;微波合成掺杂LiMxMn2O4(M=La;Nd;Y)的电化学性能     

微波合成掺杂LiM_xMn_2O_4(M=La,Nd,Y)的电化学性能

以 L i2 CO3、Mn( NO3) 2 和 M( NO3) 3( M=L a,Nd,Y)为原材料 ,用溶胶 -凝胶方法和微波加热技术合成了纳米级尖晶石 L i Mx Mn2 O4 ( M=L a,Nd,Y)材料 ,XRD实验表明 ,微波合成的材料相纯度较高 ,充放电实验表明 ,在 L i Mn2 O4 中掺杂摩尔比为 0 .0 0 6的 L a、Nd和 Y可以提高其电化学比容量和充放电循环性能 .     

Synthesis and characterization of a silylated Brazilian clay mineral surface

Clay mineral containing kaolinite, illite and montmorillonite was organofunctionalized with silylating agents: (3-aminopropyl)triethoxysilane, 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane and (3-mercaptopropyl)trimethoxy-silane, to yield three hybrids labelled Clay1, Clay2 and Clay3, respectively. These solids were characterized using elemental analysis, thermogravimetry, X-ray diffractometry, infrared spectroscopy, scanning electron micrograph, and ²⁹Si and ²⁷Al solid state NMR. Immobilized quantities of the organic groups were 0.66 mmol g^?1, 0.48 mmol g^?1 and 0.88 mmol g^?1 for Clayx (x = 1–3), respectively. X-ray diffraction patterns confirmed the immobilization of silanes onto the surface without changes in the textural properties of the clay mineral as noted from the SEM images. Spectroscopic measurements were in agreement with the covalent bonding between the silanes and the hydroxyl groups deposited on the surface. The new hybrids were utilized as adsorbents of cobalt in aqueous solution, with retention values of 0.78 mmol g^?1, 1.1 mmol g^?1 and 0.70 mmol g^?1 for Clayx (x = 1–3), respectively.     

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.