OH(3) (-) and O(2)H(5) (-) double Rydberg anions: predictions and comparisons with NH(4) (-) and N(2)H(7) (-)

A low barrier in the reaction pathway between the double Rydberg isomer of OH(3) (-) and a hydride-water complex indicates that the former species is more difficult to isolate and characterize through anion photoelectron spectroscopy than the well known double Rydberg anion (DRA), tetrahedral NH(4) (-). Electron propagator calculations of vertical electron detachment energies (VEDEs) and isosurface plots of the electron localization function disclose that the transition state's electronic structure more closely resembles that of the DRA than that of the hydride-water complex. Possible stabilization of the OH(3) (-) DRA through hydrogen bonding or ion-dipole interactions is examined through calculations on O(2)H(5) (-) species. Three O(2)H(5) (-) minima with H(-)(H(2)O)(2), hydrogen-bridged, and DRA-molecule structures resemble previously discovered N(2)H(7) (-) species and have well separated VEDEs that may be observable in anion photoelectron spectra.     

Further Examples of the P-O-P Connection in Borophosphates: Synthesis and Characterization of Li(2) Cs(2) B(2) P(4) O(15) , LiK(2) BP(2) O(8) , and Li(3) M(2) BP(4) O(14) (M=K, Rb)

A new series of anhydrous mixed alkali-metal borophosphates-Li(2) Cs(2) B(2) P(4) O(15) (1), LiK(2) BP(2) O(8) (2), Li(3) K(2) BP(4) O(14) (3), and Li(3) Rb(2) BP(4) O(14) (4)-have been successfully synthesized by using the conventional solid-state reaction method. Compound 1 contains a novel fundamental building unit (FBU), [B(4) P(8) O(30) ], with B/P=1:2. Compound 2 contains an FBU of [B(2) P(4) O(16) ] with B/P=1:2. Compounds 3 and 4 are isotypic, and they have a [B(P(2) O(7) )(2) ] unit as their FBU. In all four compounds, their FBUs are connected through corner sharing to generate layered anionic partial structures, and then further linked with metallic polyhedra to form three-dimensional (3D) frameworks. Most interestingly, three of the four compounds contain direct P-O-P connections in their structures, which is extremely rare among borophosphates. Thermal analyses, IR spectroscopy, and UV/Vis/near-IR diffuse reflectance spectroscopy have also been performed on the four title compounds.     

Acidites et complexes des acides (alkyl-et aminoalkyl-) phosphoniques-IV: acides aminoalkylphosphoniques R(1)R(2)N(CH(2))(n)CR(3)R(4)PO(3)H(2)

The acids under study differed from one another in length of the carbon chain [N + H(3)(CH(2))(n)PO(3)H(-) for n = 1, 2, 3], substitution on the nitrogen atom [R(1)R(2)N + HCH(2)PO(3)H(-) for R(1) = H; R(2) = Me, Et and R(1) = R(2)= Me, Et] or extent of branching on the carbon atom adjacent to functional groups [N + H(3)CR(3)R(4)PO(3)H(-) for R(3) = H; R(4) = Me, Et, nPr, iPr, nBu and R(3) = R(4) = Me]. Acidity constants and overall stability constants of complexes formed with Ca(II), Mg(II), Co(II), Ni(II), Cu(II), Zn(II) were obtained with the multiparametric refinement programs MUPROT and MUCOMP, applied to potentiometric data, obtained at 25 degrees , in a 0.1M potassium nitrate medium. In the most general case, the existing species are MHA(+), MA, M(OH)A(-), MH(2)A(2), MHA(-)(2) and MA(2-)(2), where A(2-) stands for the fully ionized ligand; preliminary examination of results points out some predominant microscopic forms.     

Surface X-ray scattering of stepped surfaces of platinum in an electrochemical environment: Pt(331) = 3(111)-(111) and Pt(511) = 3(100)-(111)

Real surface structures of the high-index planes of Pt with three atomic rows of terraces (Pt(331) = 3(111)-(111) and Pt(511) = 3(100)-(111)) have been determined in 0.1 M HClO(4) at 0.1 and 0.5 V(RHE) with the use of surface X-ray scattering (SXS). The surfaces with two atomic rows of terraces, Pt(110) = 2(111)-(111) and Pt(311) = 2(100)-(111) = 2(111)-(100), are reconstructed to a (1 × 2) structure according to previous studies. However, the surfaces with three atomic rows of terraces have pseudo-(1 × 1) structures. The interlayer spacing between the first and the second layers, d(12), is expanded 13% on Pt(331) compared to that of the bulk, whereas it is contracted 37% on Pt(511). The surface structures do not depend on the applied potential on either surface.     

Oxidation of bis(4-toluenesulphonyl-L-serinato)copper(II) to bis(formylglycine)copper(II)

Summary Oxidation of L-serine occurs on degradation of bis(L-serinato)copper(II) and at the same time copper is reduced.     

Bismuth(V) iron(III) tris(phosphate) oxide

Bi^V_0.4Fe₃^IIIO(PO₄)₃ crystallizes with two Fe atoms (one on an inversion centre and one on a mirror plane) displaying octahedral geometry and a third Fe atom (on a mirror plane) with trigonal bipyramidal coordination. Fe atoms are seen in oxy­gen‐bridged chains. Bi^V atoms are found in the interstitial sites between these chains. Bi shows sevenfold coordination, with Bi—O distances between 2.357 (7) and 2.529 (6) Å.     

Osmium Complexes of 1,4,7-Triazacyclononane (tacn) and 1,4,7-Trimethyl-1,4,7-triazacyclononane (Me(3)tacn) and the X-ray Crystal Structure of [(Me(3)tacn)Os(eta(6)-C(6)H(5)BPh(3))]BPh(4).CH(3)CN

The complexes of osmium with tacn (1,4,7-triazacyclononane) and Me(3)tacn (1,4,7-trimethyl-1,4,7-triazacyclononane), [LOs (eta(6)-C(6)H(6))](PF(6))(2) (L = tacn) and LOsCl(3) (L = tacn, Me(3)tacn), have been prepared by substitution of L on [Os(eta(6)-C(6)H(6))Cl(2)](2) or [Os(2)Cl(8)](2)(-), respectively. Reaction of LOsCl(3) with neat triflic acid leads to partial replacement of chloride and formation of the binuclear Os(III)-Os(III) complexes [LOs(&mgr;-Cl(3))OsL](PF(6))(3) (L = tacn, Me(3)tacn). The binuclear nature was established by NMR spectroscopy and elemental analysis and, for L = tacn, a partially refined X-ray crystal structure which shows the Os-Os separation to be 2.667 ?, indicative of significant metal-metal bonding. Reduction of [LOs(&mgr;-Cl(3))OsL](3+) over zinc amalgam in either aqueous or non-aqueous solution yields the intensely colored Os(II)-Os(III) mixed-valence ions [LOs(&mgr;-Cl(3))OsL](2+). Electrochemical measurements on [LOs(&mgr;-Cl(3))OsL](3+) in CH(3)CN reveal the reversible formation of the mixed valence ions. These are further reduced at lower potential to the Os(II)-Os(II) binuclear species, reversibly for L = Me(3)tacn. (Me(3)tacn)OsCl(3) is oxidized by persulfate ion to give [(Me(3)tacn)OsCl(3)](+); zinc amalgam reduction in an aqueous solution at high concentration produces the binuclear complex [(Me(3)tacn)Os(&mgr;-Cl(3))Os(Me(3)tacn)](3+) or, at low concentration, a solution containing an air sensitive osmium(II) species. Addition of BPh(4)(-) results in the eta(6)-arene zwitterion [(Me(3)tacn)Os(eta(6)-C(6)H(5)BPh(3))](+), which was characterized by X-ray diffraction on the BPh(4)(-) salt. The compound crystallizes in the triclinic space group P1 with a = 11.829(2) ?, b = 12.480(3) ?, c = 17.155(4) ?, alpha = 84.42(2) degrees, beta = 83.52(2) degrees, gamma = 71.45(2) degrees, V = 2380(2) ?(3), Z = 2, and R = 7.62%, and R(w) = 7.39%.     

Exploratory synthesis in molten salts: role of flux basicity in the stabilization of the complex thiogermanates Cs(4)Pb(4)Ge(5)S(16), K(2)PbGe(2)S(6), and K(4)Sn(3)Ge(3)S(14)

The influence of the Lewis basicity of alkali polysulfide fluxes (A(2)S(x)) (A = alkali) as a function of x on the respective reactivities of Pb and Sn with Ge was studied and found to be strong. Cs(4)Pb(4)Ge(5)S(16), K(2)PbGe(2)S(6), and K(4)Sn(3)Ge(3)S(14) could be prepared only under low basicity with S/A(2)S ratios of > or =11. These compounds display complex frameworks and are semiconductors. Cs(4)Pb(4)Ge(5)S(16) is luminescent with red emission.     

NMR Characterization of the Na(3)AlP(3)O(9)N and Na(2)Mg(2)P(3)O(9)N Nitridophosphates: Location of the (NaAl)/Mg(2) Substitution

We report a solid state nuclear magnetic resonance study of (23)Na, (27)Al, and (31)P in two crystalline nitridophosphate phases, Na(3)AlP(3)O(9)N and Na(2)Mg(2)P(3)O(9)N, including two-dimensional multiple-quantum magic angle spinning (MQ-MAS) experiments on (23)Na to separate overlapping lines. The previously described single-crystal structure of Na(3)AlP(3)O(9)N gives crystallographic examples of Al(OP)(6) and P(O[Al,Na])(2)(ONa)(N[P,Na]) environments and three different environments of sodium: two Na(O)(6) and one Na(O)(6)(N). From these observations we characterize the modification of the local environment of phosphorus and show that Mg only substitutes Na in the Na2 site of the Na(2)Mg(2)P(3)O(9)N structure.     

Adsorption of zinc(II) and copper(II) to Shirasu (pyroclastic flow)

A fundamental study on the adsorption of metal elements on Shirasu, a pyroclastic flow deposit distributed in southern Kyushu, Japan, has been conducted. The adsorption experiment was carried out by a batch method, and by using Zn(II) and Cu(II) under several conditions; the effects of the initial concentration of metal ions, grain size, and pH were investigated. At smaller grain sizes, the amount of Zn(II) and Cu(II) adsorbed increased. At higher pH values, the amount of Zn(II) and Cu(II) adsorbed increased. Plots of the adsorption isotherm indicated that the adsorption of Zn(II) and Cu(II) on Shirasu followed the Langmuir isotherm model, and the Langmuir isotherm constants, W(0) and b, were obtained. W(0) at pH 5.0 was approximately two-times larger than that at pH 3.0. This may reflect an increase in the number of anionic binding sites on the surface of Shirasu with an increase in the pH. The b value for Zn hardly changed with an increase in the pH, and for Cu the value decreased with an increase in the pH. These observations suggest that anionic binding sites have a low stability constant, since the apparent stability constant, b, is obtained as the average of stability constant of all sites on the Shirasu surface.     

Reaction of (chloromethyl)phosphonic(-phosphinic) iso(thio)cyanates with alcohols and (α-hydroxyalkyl)phosphonates

Alcohols and α-hydroxyphosphonates undergo the addition to (chloromethyl)phosphonic(-phosphinic) iso(thio)cyanates, yielding phosphorylated (thio)urethanes. The latter undergo cyclization to form, depending on their structure, saturated or unsaturated five-membered P,N,O,S-containing heterocycles.     

First-principles study of the (001) surface of cubic SrHfO(3) and SrTiO(3)

We have performed first-principles calculations on the (001) surface of cubic SrHfO(3) and SrTiO(3) with SrO and BO(2) (B = Ti or Hf) terminations. Surface structure, partial density of states, band structure, and surface energy have been obtained. For the BO(2)-terminated surface, the largest relaxation appears on the second-layer atoms but not on the first-layer ones. The analysis of the structure relaxation parameters reveals that the rumpling of the (001) surface for SrHfO(3) with SrO termination is stronger than that for SrTiO(3). For the HfO(2)-terminated surface of SrHfO(3), the surface state appears near the M point of its band structure.     

Solid state NMR characterization of individual compounds and solid solutions formed in Sc(2)O(3)--V(2)O(5)--Nb(2)O(5)--Ta(2)O(5) system

In this study, (51)V, (45)Sc and (93)Nb MAS NMR combined with satellite transition spectroscopy analysis were used to characterize the complex solid mixtures: VNb(9(1-x))Ta(9x)O(25), ScNb((1-x))Ta(x)O(4) and ScNb(2(1-x))Ta(2x)VO(9) (x = 0, 0.3, 0.5, 0.7, 1.0). This led us to describe the structures of Sc and V sites. The conclusions were based on accurate values for (51)V quadrupole coupling and chemical shift tensors obtained with (51)V MAS NMR/SATRAS for VNb(9)O(25), VTa(9)O(25) and ScVO(4). The (45)Sc NMR parameters have been obtained for Sc(2)O(3), ScVO(4), ScNbO(4) and ScTaO(4). On the basis of (45)Sc NMR and data available from literature, the ranges of the (45)Sc chemical shift have been established for ScO(6) and ScO(8). The gradual change of the (45)Sc and (51)V NMR parameters with x confirms the formation of solid solutions in the process of synthesis of VNb(9(1-x))Ta(9x)O(25) and ScNb((1-x))Ta(x)O(4), in contrast to ScNb(2(1-x))Ta(2x)VO(9). The cation sublattice of ScNb((1-x))Ta(x)O(4) is found to be in octahedral coordination. The V sites in VNb(9(1-x))Ta(9x)O(25) are present in the form of slightly distorted tetrahedra. The (93)Nb NMR parameters have been obtained for VNb(9)O(25).     

(1-x)La_(0.67)Ca_(0.33)MnO_3/xCuO复合体系与La_(0.67)Ca_(0.33)Mn_(1-x)Cu_xO_3电输运行为比较

用不同实验方法制备了名义组分为(1-x)La_(0.67)Ca_(0.33)MnO_3/xCuO(LCMO/CuO)和La_(0.67)Ca_(0.33)Mn_(1-x)Cu_xO_3(LCMCO)两组样品,在宽的温度范围内研究了样品的电输运行为随Cu含量x的变化关系,发现这两组样品表现出不同的行为.对于LCMCO,随x的增加,金属-绝缘体转变温度T_p迅速降低,当x=5.5%,样品表现出绝缘体导电行为;而LCMO/CuO复合样品,当x≤6%时,随x增加,Tp逐渐下降,x≥6%时,T_p不再继续降低,所有样品几乎表现出相同的电输运行为.另外,这两组样品均表现出较好的低场磁电阻效应(LFMR),在0.3 T下样品的最大磁电阻分别达到了～76%和88%.基于样品结构以及制备过程的分析,我们认为LFMR效应的增强主要是因为颗粒边界上形成的Cu相关自旋无序层引起的.     

Synthesis of (pentacarbonyl)tungstate(−1) and (pentacarbonyl)molybdate(−1) dinucleotides

New methods for preparation of metallo dinucleotides with transition metals directly bonded to phosphorus are presented. (Pentacarbonyl)tungstate(−1) and (pentacarbonyl)molybdate(−1) dimers are prepared by the reaction of dinucleotide-H-phosphonate with M(CO)₅(THF) (M = W, Mo). These syntheses can be completed in solution or on solid-phase.     

A first-principles study of (R)- and (S)-PPA Molecules on Cu(111)

The adsorption of (R)- and (S)-2-phenylpropionamide (PPA, C(9)H(11)ON) molecules on a Cu(111) surface has been investigated using the density functional method with supercell models. The adsorption orientations of both (R)- and (S)-PPA molecules on the surface are the same: the phenyl rings are approximately parallel to the Cu(111) surface and positioned in the hollow sites, the amino and methyl groups occupy two-bridge sites, and the carbonyl occupies the top site. After the adsorption, the bond lengths in the two enantiomers are almost unchanged, but the changes for two dihedral angles show differences, especially for (R)-PPA molecule. The first angles between the (N,C9,C7) plane and the (C9,C7,C6) plane are 19.4 and 0.7 degrees for (R)- and (S)-PPA molecules, respectively, and the second angles between the (C8,C7,C6) plane and the (C7,C6,C5) plane are 74.8 and 0.4 degrees for (R)- and (S)-PPA molecules, respectively. The adsorption energies of (R)- and (S)-PPA molecules are calculated to be -34 and -26 kJ mol(-1), respectively. The simulated scanning tunneling microscopy (STM) images of (R)- and (S)-PPA molecules on the Cu(111) surface display different features and are coincident with the experimental ones. The interaction between the adsorption molecule and the metal surface is found to be responsible for the discrimination of (R)- and (S)-PPA molecules on the surface.     

Interaction of bis(ethylene)tin(bis(salicylidene)ethylenediamine) with DNA.

The fluorescence spectral characteristics and interaction of bis(ethylene)tin(bis(salicylidene)ethylenediamine) [Et2Sn(salen)] with DNA are described. The polarity of the solvent has a strong effect on the fluorescence characteristics of Et2Sn(salen). Et2Sn(salen) bound to DNA showed a marked decrease in the fluorescence intensity with a bathochromic shift of the excitation and emission peaks. A hypochromism in the UV absorption spectra was also observed. KI quenching and competitive binding to DNA between Et2Sn(salen) and ethidium bromide (EB) were studied in connection with other experimental observations to show that the interactive model between Et2Sn(salen) and DNA is an intercalative one. The pH and salt effect on the fluorescence properties was also investigated. The intrinsic binding constant was estimated to be 1.071 x 10(5) mol L(-1) in base pairs and the binding site number is 1.98, respectively. A linear relationship between F/F0 and the concentration of calf thymus DNA covers 5.1 x 10(-6) - 2.41 x 10(-4) mol L(-1), which can be utilized for determining traces of calf thymus DNA with a detection limit of 1.1 x 10(-7) mol L(-1) in base pairs.     

Preparation and characterization of bis(acetonitrile)bis(acetylacetonato)technetium(III)

A new chemical species of bis(acetonitrile)bis(acetylacetonato)technetium(III), [Tc(acac)₂(CH₃CN)₂]⁺, has been prepared by the reaction of tris(acetylacetonato)technetium(III) with acetonitrile in the presence of a strong acid, perchloric or hydrochloric acid. The reaction kinetics were followed by observing spectral change of Tc(acac)₃ in the UV-visible region. The complex has been characterized by combination of elemental analyses, IR and UV-visible spectrophotometry, ion-exchange chromatography, and paper electrophoresis. Applicability of this substance to synthesize mixed-ligand technetium(III) complexes was discussed based on the solubility of this complex and the ease of substitution of the acetonitrile ligand.     

Photoelectron spectroscopy and density functional theory study of TiAlO(y) (-) (y=1-3) and TiAl(2)O(y) (-) (y=2-3) clusters

Small titanium-aluminum oxide clusters, TiAlO(y) (-) (y=1-3) and TiAl(2)O(y) (-) (y=2-3), were studied by using anion photoelectron spectroscopy. The adiabatic detachment energies of TiAlO(y) (-) (y=1-3) were estimated to be 1.11±0.05, 1.70±0.08, and 2.47±0.08eV based on their photoelectron spectra; those of TiAl(2)O(2) (-) and TiAl(2)O(3) (-) were estimated to be 1.17±0.08 and 2.2±0.1eV, respectively. The structures of these clusters were determined by comparison of density functional calculations with the experimental results. The structure of TiAlO(-) is nearly linear with the O atom in the middle. That of TiAlO(2) (-) is a kite-shaped structure. TiAlO(3) (-) has a kite-shaped TiAlO(2) unit with the third O atom attaching to the Ti atom. TiAl(2)O(2) (-) has two nearly degenerate Al-O-Ti-O-Al chain structures that can be considered as cis and trans forms. TiAl(2)O(3) (-) has two low-lying isomers, kite structure and book structure. The structures of these clusters indicate that the Ti atom tends to bind to more O atoms.