(Li/Ag)CoO2: a new intergrowth cobalt oxide composed of rock salt and delafossite layers

A new ordered (Li/Ag)CoO(2) layered compound with an unusual oxygen packing combining rock salt and delafossite layers is obtained during the (Li(+), Na(+))/Ag(+) ionic exchange from the OP4-(Li/Na)CoO(2) precursor. This compound is actually an intermediate step to the final D4-AgCoO(2) delafossite and can be isolated thanks to the kinetics difference between the Li(+)/Ag(+) and Na(+)/Ag(+) exchange processes. It crystallizes in the P6(3)/mmc space group with cell parameters a(hex.) = 2.848(3) ? and c(hex.) = 21.607(7) ?. The details of the structure as well as its thermal stability and transport properties are presented and discussed.     

Synthesis and crystal structure of Ae(2)LiInGe(2) (Ae = Ca, Sr): new Zintl phases with a layered silicate-like network

Two new Zintl phases Ae(2)LiInGe(2) (Ae = Ca 1; Sr 2) were obtained from stoichiometric reactions of the pure elements in sealed Nb tubing at 1000-1050 degrees C. The isomorphous polar intermetallic phases crystallize in the orthorhombic space group Pnma, with cell constants of a = 7.2512(7), b = 4.4380(5), and c = 16.902(1) A for compound 1, and a = 7.5033(8), b = 4.6194(5), and c = 17.473(2) A for compound 2. The crystal structure can be derived from the vertex-sharing of InGe(4/2) tetrahedral units that form "corrugated" sheets normal to the crystallographic c-axis. Calcium and lithium atoms act as "spacers" that effectively separate the anionic [InGe(2)](5-) layers. The layered anionic substructure is similar to those exhibited by layered metal oxides, sulfides, and silicates. The connectivity of the tetrahedral building unit, [InGe(4/2)](5-), is analogous and isoelectronic to the silicate [SiO(4/2)] unit.     

Synthesis, structure and properties of a new Zintl phase: SrLiSb

A new ternary antimonide SrLiSb has been synthesized and characterized using single-crystal X-ray studies. It is found to crystallize in the anti-PbCl₂ structure type with orthorhombic cell (centrosymmetric S.G., Pnma; , , ) and is isostructural to its calcium analogue (CaLiSb). However, BaLiSb has been reported to crystallize in the hexagonal space group P6₃/mmc. As in the Ca and Ba analogues, antimony is present as isolated Sb³⁻ ions making SrLiSb electron precise and hence is expected to behave as a classical Zintl compound. The magnetic susceptibility measurements show the diamagnetic nature and the conductivity is temperature independent, both verifying the classical Zintl nature of SrLiSb.     

Novel corrugated In9 anionic layer in Li2Y5In9: square pyramidal In5 clusters interconnected by unusual butterfly In4 clusters

The new ternary polar intermetallic phase, Li2Y5In9, was obtained by high-temperature solid-state reactions of the corresponding elements inwelded Ta tubes. Its crystal structure was established by a single-crystal X-ray diffraction study. Li2Y5In9 crystallizes in the tetragonal space group P4/nmm (No. 129) with cell parameters of a = b = 10.1242(4), c = 15.1091(10) A and Z = 4. The structure of Li2Y5In9 features a two-dimensional corrugated anionic In9 layer composed of two types of square pyramidal In5 units and butterfly In4 units. There are two types of square pyramidal In5 units: one with normal In-In bonds and another one with greatly elongated In-In separations within its In4 square. Packing of these 2D In9 layers resulted in cavities and tunnels that are occupied by Y and Li atoms. Extended-Hückel tight-binding calculations indicate that Li2Y5In9 is metallic.     

KNa(3)In(9): a Zintl network phase built of layered indium icosahedra and zigzag chains. Synthesis,structure, bonding,and properties

This phase was discovered following direct fusion of the elements in welded Nb tubes at 550 degrees C and equilibration at 300 degrees C for 1 week. Single-crystal X-ray diffraction analysis reveals that KNa(3)In(9) crystallizes in an orthorhombic system (Cmca, Z = 8, a = 9.960(1) A, b =16.564(2) A, c = 17.530(2) A, 23 degrees C). The structure contains a three-dimensional indium network built of layers of empty In(12) icosahedra that are each 12-bonded and interconnected by 4-bonded indium atoms that also form zigzag chains. All cations bridge between cluster faces or edges, and their mixed sizes appear critical to the stability of this particular structure, which does not occur in either binary system. Both empirical electron counting and EHTB band structure calculations on the macroanion indicate that the bonding in this structure is closed-shell, whereas resistivity and magnetic susceptibility measures show that the compound is a moderately poor metal.     

Synthesis and characterization of transition-metal Zintl phases: Cs24Nb2In12As18 and Cs13Nb2In6As10 with isolated complex anions

The title compounds were prepared by direct reaction of the corresponding elements at high temperature. Their structures were determined by single-crystal X-ray diffraction (Cs24Nb2In12As18, triclinic, P1, Z=1, a=9.519(4), b=9.540(5), and c=25.16(1) A, alpha=86.87(4), beta=87.20(4), and gamma=63.81(4) degrees; Cs13Nb2In6As10, triclinic, P1, Z=1, a=9.5564(5), b=9.6288(5), and c=13.9071(7) A, alpha=83.7911(8), beta=80.2973(8), and gamma=64.9796(8) degrees). Cs24Nb2In12As18 and Cs13Nb2In6As10 contain isolated anions of [Nb2In12As18](24-) and [Nb2In6As10](13-), respectively. Each anion includes two cubane-like units made of one niobium, three indium, and four arsenic corners where a fifth arsenic atom completes the tetrahedral coordination at niobium, [(NbAs)In3As4]. In Cs13Nb2In6As10 these two units are connected via a direct In-In bond between two indium vertexes of the cubanes. In Cs24Nb2In12As18, on the other hand, the same two units are linked by a dimer made of semicubanes of [In3As4], i.e., a cubane with one missing vertex. Magnetic measurements show that Cs24Nb2In12As18 is diamagnetic, i.e., a d0 transition-metal Zintl phase, while Cs13Nb2In6As10 exhibits a Curie-Weiss behavior that corresponds to one unpaired electron.     

Synthesis and structure of Ag(6)[(UO(2))(3)O(MoO(4))(5)]: a novel sheet of triuranyl clusters and MoO(4) tetrahedra

The new uranyl molybdate Ag(6)[(UO(2))(3)O(MoO(4))(5)] (1) with an unprecedented uranyl molybdate sheet has been synthesized at 650 degrees C. The structure (monoclinic, C2/c, a = 16.4508(14) A, b = 11.3236(14) A, c = 12.4718(13) A, beta = 100.014(4)(o), V = 2337.4(4) A(3), Z = 4) contains [(UO(2))(3)O(MoO(4))(5)] sheets composed of triuranyl [(UO(2))(3)O] clusters that are connected by MoO(4) tetrahedra. The topology of the uranyl molybdate sheet in 1 represents a major departure from sheets observed in other uranyl compounds. Of the approximately 120 known inorganic uranyl compounds containing sheets of polyhedra, 1 is the only structure that contains trimers of uranyl pentagonal bipyramids that are connected only by the sharing of vertexes with other polyhedra. The sheets are parallel to (001) and are linked by Ag cations.     

New tetragonal structure type for A2Ca10S(9 (A = Li, Mg). Electronic variability around a Zintl phase

The phases LiMgCa(10)Sb(9) (1), Mg(2)Ca(10)Sb(9) (2), and Li(1.38(2))Ca(10.62)Sb(9) (3) have been synthesized by high-temperature solid-state means and characterized by single-crystal means and property measurements. These occur in space group P4(2)/mnm, Z = 4, with a = 11.8658(5), 11.8438(6), 11.9053(7) Angstroms and c = 17.181(2), 17.297(2), 17.152(2) Angstroms, respectively. The two types of A atoms occupy characteristic sites in a Ca-Sb network that contains a 5:2 proportion of (formal) Sb(3-) and Sb(2)(4-) anions and can be described in terms of two slab types stacked along [001]. Bonding appears to be strong in these salts with generally normal distances and high coordination numbers except for the 4-bonded atoms in a C(2)(v) position for the second type of A that is occupied by Li, Mg or Ca(0.62(2))Li(0.38), respectively. The three compounds are, respectively, an ideal electron-precise Zintl phase, one e(-)-rich and 0.40(4) e(-)-short per formula unit. The LiMgCa(10)Sb(9) compound is correspondingly diamagnetic and presumably a semiconductor.     

A novel one-dimensional organic-inorganic polymer: synthesis and crystal structure of[{Ca(DMF)_5}_2SiMo_(12)O_(40)]_n

A novel polyoxometalate-based organic-inorganic polymer [{Ca(DMF)5}2SiMo12O40]n has been synthesized and characterized by elemental analysis, IR, UV and X-ray single-crystal structural analysis. The title compound crystallizes in a monocline lattice, P21/n, with a =1.3379(3), b = 1.9796(4), c = 1.4574(3) nm, β = 92.24(3)°, V = 3.8568(13) nm3, Z = 2, R1 = 0.083 and Rw = 0.2065. The result of crystal structure analysis indicates that Ca2+ is surrounded by seven coordination oxygen atoms with pentagonal bipyramidal geometry and bridged with terminal oxygen atom of polyanion in the structure. The compound contains an unprecedented one-dimensional linear chain built by alternate polyanions and cationic units through Mo-Od-Ca-O-Ca links in crystal. The IR spectra and X-ray crystallography analysis exhibit that there is a strong interaction between the polyanion and organic group in solid state. The electronic spectra (λ = 200-500 nm) for the title compound dissolved in the mixed solvent of acetonitrile and     

Binding energies of small lithium clusters (Li(n)) and hydrogenated lithium clusters (Li(n)H)

Large coupled cluster computations utilizing the Dunning weighted correlation-consistent polarized core-valence (cc-pwCVXZ) hierarchy of basis sets have been conducted, resulting in a panoply of internally consistent geometries and atomization energies for small Li(n) and Li(n)H (n=1-4) clusters. In contrast to previous ab initio results, we predict a monotonic increase in atomization energies per atom with increasing cluster size for lithium clusters, in accordance with the historical Knudsen-effusion measurements of Wu. For hydrogenated lithium clusters, our results support previous theoretical work concerning the relatively low atomization energy per atom for Li(2)H compared to LiH and Li(3)H. The CCSD(T)/cc-pwCVQZ atomization energies for LiH, Li(2)H, Li(3)H, and the most stable isomer of Li(4)H, including zero-point energy corrections, are 55.7, 79.6, 113.0, and 130.6 kcal/mol, respectively. The latter results are not consistent with the most recent experiments of Wu.     

A novel mixed-metal borate with large [B12O18(OH)6]6- motif: Synthesis,structure and property

A new mixed-metal polyborate, Na₅Li[B₁₂O₁₈(OH)₆]·2H₂O (1), has been synthesized using solvothermal method and characterized by IR spectroscopy, thermogravimetric analysis, UV–Vis spectroscopy, powder and single-crystal X-ray diffraction, respectively. It crystallizes in the trigonal space group R-3c (No. 167) with unit cell parameters of a = b = 9.6767(6) Å, c = 36.358(5) Å, and Z = 6. Its structure features unprecedented 3D framework constructed from novel honeycomb-shaped inorganic Na-O sheets with unique 12-MR sodium rings and supramolecular polyborate 2D layers of lithium-centered [B₁₂O₁₈(OH)₆]^6-. UV–Vis spectral characterization indicates that compound 1 is a wide-band-gap semiconductor.     

Negative magnetoresistance in a magnetic semiconducting Zintl phase: Eu(3)In(2)P(4)

A new rare earth metal Zintl phase, Eu(3)In(2)P(4), was synthesized by utilizing a metal flux method. The compound crystallizes in the orthorhombic space group Pnnm with the cell parameters a = 16.097(3) A, b = 6.6992(13) A, c = 4.2712(9) A, and Z = 2 (T = 90(2) K, R1 = 0.0159, wR2 = 0.0418 for all data). It is isostructural to Sr(3)In(2)P(4). The structure consists of tetrahedral dimers, [In(2)P(2)P(4/2)](6-), that form a one-dimensional chain along the c axis. Three europium atoms interact via a Eu-Eu distance of 3.7401(6) A to form a straight line triplet. Single-crystal magnetic measurements show anisotropy at 30 K and a magnetic transition at 14.5 K. High-temperature data give a positive Weiss constant, which suggests ferromagnetism, while the shape of susceptibility curves (chi vs T) suggests antiferromagnetism. Heat capacity shows a magnetic transition at 14.5 K that is suppressed with field. This compound is a semiconductor according to the temperature-dependent resistivity measurements with a room-temperature resistivity of 0.005(1) Omega m and E(g) = 0.452(4) eV. It shows negative magnetoresistance below the magnetic ordering temperature. The maximum magnetoresistance (Deltarho/rho(H)) is 30% at 2 K with H = 5 T.     

In situ neutron diffraction study of Li insertion in Li4Ti5O12

Developing an efficient in situ electrochemical cell for neutron diffraction of electrode materials for Li-ion batteries remains a major technical challenge. We recently published the results of the first experiment carried out with such a cell developed by our group. In order to improve the quality of data we optimized the preparation of the electrode, introduced a gradient in the carbon content, and controlled the porosity. Li₄Ti₅O₁₂ was used as a model material to demonstrate the advantages of the new approach. 10 diffractograms were recorded in situ during the first electrochemical cycle and then refined to obtain the evolution of unit cell parameters, oxygen position, and of the quantitative ratio between Li₄Ti₅O₁₂ and Li₇Ti₅O₁₂.     

Synthesis,structure and properties of three novel transition-metal-containing tantalum-phosphate clusters

Peroxide ligation of aqueous metal–oxo clusters provides rich speciation and structural diversity. Here, three novel transition-metal derivatives of polyoxometalate anions, [Ni₂(H₂O)₁₀{P₄Ta₆(O₂)₆O₂₄}]^6– (1a), [Zn(H₂O)₄{P₄Ta₆(O₂)₆O₂₄}]^8– (2a) and [Cd(H₂O)₄{P₄Ta₆(O₂)₆O₂₄}]^8– (3a), have been successfully synthesized by adopting a one-pot reaction strategy. All of these hexatantalates are built from a new-type phosphorus-incorporated hexatantalates. We investigated the solution behaviors, and the peak assignments of the MS spectra indicated some degree of stability of them in water. Furthermore, the proton-conducting ability of compound 1a was also explored and it has shown well conductivity at high relative humidities, with conductivity achieved 1.22 × 10^–3 S/cm (85 °C, 90%RH).     

Synthesis and characterization of the largest isolated clusters of tin, [Sn12](12-), in (AE)Na10Sn12 (AE = Ca or Sr)

Reported are two isostructural Zintl compounds, CaNa(10)Sn(12) and SrNa(10)Sn(12), with mixed alkali and alkaline-earth cations and isolated clusters of Sn(12)(12-) with the shape of giant truncated tetrahedra. The compounds were synthesized by heating the corresponding mixtures of elements at 950 degrees C. The structures were solved and refined from single-crystal X-ray diffraction data in the cubic space group I43m (No. 217), where Z = 2 with a = 11.1847(6) and 11.2176(4) A for CaNa(10)Sn(12) and SrNa(10)Sn(12), respectively. Both compounds are diamagnetic and therefore electronically balanced.     

Resolving the different silicon clusters in Li12Si7 by 29Si and (6,7)Li solid-state NMR spectroscopy

Structural signatures: The analysis of Si-Si and Si-Li connectivities by solid-state NMR spectroscopy allows the different types of silicon clusters to be discriminated in the model lithium silicide compound Li(12)Si(7) (see picture, Si clusters red and blue, Li ions gray). The results provide new NMR spectroscopic strategies with which to differentiate and study the structures formed in silicon-based electrode materials.     

Double-icosahedral Li clusters in a new binary compound Ba(19)Li(44): a reinvestigation of the Ba-Li phase diagram

The binary Ba-Li system was reinvestigated for compositions with less than 80 at. % Li. A new compound, Ba(19)Li(44), stable up to 126 degrees C, was found and structurally characterized. According to single-crystal X-ray diffraction data, the compound crystallizes in a new structure type with a tetragonal unit cell, space group I42d, a = 16.3911(5) Angstrom, c = 32.712(1) Angstrom, Z = 4, and V = 8788.7(5) Angstrom(3). It can be described as a complicated variant of the chalcopyrite structure. Typical for Li-rich phases, Ba(19)Li(44) contains icosahedron-based polytetrahedral clusters.     

Li4Ti5Ol2的合成及对Li+的离子交换动力学

用溶胶-凝胶法合成出Li4Ti5Ol2, 对其进行了酸改性, 制得锂离子筛IE-H. 测定了IE-H对Li+、Na+的饱和交换容量和pH滴定曲线等离子交换性能, 并对其进行了X射线衍射分析, 同时采用中断接触法判断该离子交换反应的控制机理, 用缩核模型描述离子筛IE-H交换Li+的动力学. 结果表明, 合成出的Li4Ti5Ol2和锂离子筛IE-H均为尖晶石结构; 用不同浓度HNO3溶液处理Li4Ti5Ol2时, Li+的抽出率为19.6%-81.5%, Ti4+的抽出率在4.2%以下; 锂离子筛IE-H 对Li+的饱和交换容量较高, 达到5.95 mmol·g-1, 离子筛IE-H交换Li+的控制步骤是颗粒扩散控制(PDC), 得到了25 ℃, Li+浓度为20.0 mmol·L-1和5.0 mmol·L-1时锂离子筛交换Li+的动力学方程和颗粒扩散系数.     

手性4-膦酸二酯基-3-卤-2(5H)-呋喃酮的合成与结构

手性呋喃酮1a-1b与亚磷酸三酯2a-2b通过串联的不对称Michael加成/分子内Michalis-Arbazov重排反应,得到了含磷官能团的新手性化合物,5-(S)-(l-孟氧基)-4-膦酸二酯基-3-卤素-2(5H)-呋喃酮4a-4d。该反应具有条件温和,产率高(86%-95%),光学纯度单一(d.e.≥98%)的特点。通过元素分析,IR,UV,^1HNMR,^1^3CNMR,MS,[α]~D^2^0波谱分析数据以及X射线四圆衍射数据确定了它们的化学结构和绝对构型。     

Synthesis,structural characterization,and electronic structure of the novel Zintl phase Ba2ZnP2

The novel Zintl phase dibarium zinc diphosphide (Ba₂ZnP₂) was synthesized for the first time. This was accomplished using the Pb flux technique, which allowed for the growth of crystals of adequate size for structural determination via single‐crystal X‐ray diffraction methods. The Ba₂ZnP₂ compound was determined to crystallize in a body‐centered orthorhombic space group, Ibam (No. 72). Formally, this crystallographic arrangement belongs to the K₂SiP₂ structure type. Therefore, the structure can be best described as infinite [ZnP₂]^4? polyanionic chains with divalent Ba²⁺ cations located between the chains. All valence electrons are partitioned, which conforms to the Zintl–Klemm concept and suggests that Ba₂ZnP₂ is a valence‐precise composition. The electronic band structure of this new compound, computed with the aid of the TB–LMTO–ASA code, shows that Ba₂ZnP₂ is an intrinsic semiconductor with a band gap of ca 0.6 eV.