(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.     

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.     

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.     

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.     

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.     

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.     

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.     

(Dibenzo-18-crown-6)potassium tetrachloroferrate(III): Synthesis and crystal structure

A new complex [K(Db18C6)]⁺[FeCl₄]^? (I) is synthesized and its structure is studied by X-ray diffraction analysis. The crystals are triclinic: space group P \(\bar 1\), a = 17.998, b = 18.670, c = 19.590 Å, α = 106.61°, β = 104.55°, γ = 113.87°, Z = 8. The structure is solved by a direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.057 by 13 670 independent reflections (CAD-4 automated diffractometer, λMoK _α). All the four independent complex cations [K(Db18C6)]⁺ are host-guest, and in each complex cation the K⁺ cation is localized in the cavity of the Db18C6 crown ligand. The coordination polyhedron of K⁺ (coordination number nine) is a distorted hexagonal bipyramid with the base of all six O atoms of the Db18C6 ligand, the axial vertex at the Cl atom of the [FeCl₄]^? anion, and another bifurcated axial vertex at two Cl atoms of another [FeCL₄]^? anion. All the four independent [FeCL₄]^? anions are orientationally disordered and have somewhat distorted tetrahedral structure. In crystal I, the alternating complex cations [K(Db18C6)]⁺ and [FeCL₄]^? anions form infinite polymer chains by the K-Cl bonds.     

(18-Crown-6)(hydrogennitrato)potassium: Synthesis and crystal structure

A new complex, [K(18-crown-6)(NO₃)(HNO₃)] (I), is synthesized, and its crystal structure is studied using X-ray diffraction analysis: space group P \(\bar 1\), a = 8.253 Å, b = 9.277 Å, c = 13.903 Å, α = 95.89°, β = 104.30°, γ = 91.89°, Z = 2. The triclinic structure of compound I was solved by a direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.059 for all 3573 independent reflections (CAD4 automated diffractometer, γMoK _α radiation). The structure of compound I contains two independent halves of two centrosymmetric complex molecules with different coordination modes of the K⁺ cations. Two NO ₃ ^? and HNO₃ ligands are randomly disordered relative to the symmetry center and are presented by two average independent H_0.5N ₃ ^1/2? , ligands, which are also orientationally disordered.     

Synthesis, structure, and bonding of open-shell Sr3In5: an unusual electron deficiency in an indium network, beyond the Zintl boundary.

The new title compound has been synthesized and characterized by physical property measurements and electronic structure calculations. The results ratify the highly uncommon deficiency of one electron that has been long speculated for its Ca3Ga5-type structure on the basis of the simple Zintl electron counting formalism. In the Sr3In5 structure (Cmcm), 4- and 2-bonded indium atoms in a 4:1 ratio form a three-dimensional classical network that encapsulates strontium atoms in its narrow channels. The electrical conductivity of the compound shows typical metallic behavior. The detailed electronic structure analysis suggests that the electron hole is mainly localized on a nonbonding p-orbital on the 2-bonded indium atoms, and that these orbitals, stacked in a sigma-type way along avector (4.97 A), interact only weakly with each other to form highly one-dimensional bands.     

Synthesis of a novel copper(II) complex and its crystal structure

One novel chiral copper(II) complex was successfully synthesized from the reaction of chiral 1,3-thiazolidine-2-thione ligand with CuCl₂ in dichloromethane in the presence of Et₃N and DMAP at room temperature. Its unique crystal structure was unambiguously disclosed by X-ray analysis. The crystal is tetragonal, space group I4(1), space group a=15.0875(11), b=15.0875(11), c=19.362(3) Å, =90, β=90, γ=90°, V=4407.4(8) ų, Z=8, ρ_calc=1.639 mg cm⁻³.     

Undulating layers in a new rhodate network: structure of Bi(1.4)CuORh5O10

A new rhodate, Bi(1.4)CuRh(5)O(11), with an hitherto unknown channel structure containing undulating layers of RhO(6) octahedra sharing corners and edges has been discovered and its structure refined from single crystal X-ray diffraction data. The channels contain Bi(3+), Cu(2+), and some O strongly bound to Cu. The Cu coordination is distorted square planar. Mixed Rh(3+)/Rh(4+) valency leads to significant electrical conductivity.     

Search for lowest-energy structure of Zintl dianion Si(12)(2-), Ge(12)(2-), and Sn(12)(2-)

We perform an unbiased search for the lowest-energy structures of Zintl dianions (Si(12)(2-), Ge(12)(2-), and Sn(12)(2-)), by using the basin-hopping (BH) global optimization method combined with density functional theory geometric optimization. High-level ab initio calculation at the coupled-cluster level is used to determine relative stabilities and energy ranking among competitive low-lying isomers of the dianions obtained from the BH search. For Si(12)(2-), all BH searches (based on independent initial structures) lead to the same lowest-energy structure Si(12a)(2-), a tricapped trigonal prism (TTP) with C(s) group symmetry. Coupled-cluster calculation, however, suggests that another TTP isomer of Si(12c)(2-) is nearly isoenergetic with Si(12a)(2-). For Sn(12)(2-), all BH searches lead to the icosahedral structure I(h)-Sn(12a)(2-), i.e., the stannaspherene. For Ge(12)(2-), however, most BH searches lead to the TTP-containing Ge(12b)(2-), while a few BH searches lead to the empty-cage icosahedral structure I(h)-Ge(12a)(2-) (named as germaniaspherene). High-level ab initio calculation indicates that I(h)-Ge(12a)(2-) and TTP-containing Ge(12b)(2-) are almost isoenergetic and, thus, both may be considered as candidates for the lowest-energy structure at 0 K. Ge(12a)(2-) has a much larger energy gap (2.04 eV) between highest occupied molecular orbital and lowest unoccupied molecular orbital than Ge(12b)(2-) (1.29 eV), while Ge(12b)(2-) has a lower free energy than I(h)-Ge(12a)(2-) at elevated temperature (>980 K). The TTP-containing Si(12a)(2-) and Ge(12b)(2-) exhibit large negative nuclear independent chemical shift (NICS) value (approximately -44) at the center of TTP, indicating aromatic character. In contrast, germaniaspherene I(h)-Ge(12a)(2-) and stannaspherene I(h)-Sn(12a)(2-) exhibit modest positive NICS values, approximately 12 and 3, respectively, at the center of the empty cage, indicating weakly antiaromatic character.     

Electronic structure and thermochemical properties of small neutral and cationic lithium clusters and boron-doped lithium clusters: Li(n)(0/+) and Li(n)B(0/+) (n = 1-8)

The stability, electronic structure, and thermochemical properties of the pure Li(n) and boron-doped Li(n)B (n = 1-8) clusters in both neutral and cationic states are studied using electronic structure methods. The global equilibrium structures are established, and their heats of formation are evaluated using the G3B3 and CCSD(T)/CBS methods based on the density functional theory geometries. Theoretical adiabatic ionization energies (IE(a)) for the Li(n) clusters are in good agreement with experiment: Li(2) (G3B3, 5.21 eV; CCSD(T), 5.14 eV; expt, 5.1127 ± 0.0003 eV), Li(3) (4.16, 4.11, 4.08 ± 0.10), Li(4) (4.76, 4.68, 4.70 ± 0.05), Li(5) (4.11, 4.06, 4.02 ± 0.10), Li(6) (4.46, 4.32, 4.20 ± 0.10), Li(7) (4.07, 3.99, 3.94 ± 0.10), and Li(8) (4.49, 4.31, 4.16 ± 0.10). The Li(4) experimental IE(a) has been revised on the basis of the Franck-Condon simulations. Species Li(5)B, Li(6)B(+), Li(7)B, and Li(8)B(+) exhibit high stability as compared to their neighbors, which can be understood by considering the magic numbers of the phenomenological shell model (PSM).