New Layered Polyborates Cs(2)M(2)B(10)O(17) (M = Na, K)

The polyborates Cs(2)M(2)B(10)O(17) (M = Na, K) have been prepared and their structures determined by single-crystal X-ray diffraction methods. They crystallize in the monoclinic space group C2/c (Z = 8) with unit-cell parameters a = 21.643(3) ?, b = 6.558(2) ?, c = 11.072(2) ?, beta = 105.43(1) degrees, V = 1514.8(6) ?(3) for the Na compound and a = 22.547(9) ?, b = 6.614(2) ?, c = 11.288(4) ?, beta = 103.25 degrees, V = 1638.3(8) ?(3) for the K analogue. The new structural type contains a 2-dimensional borate matrix that is built from a complete condensation of the ring system B(5)O(11). The Cs atoms reside within the borate matrix, and the Na (K) atoms are placed between the thick Cs borate sheets.     

A Novel Complex of Na（I）-Nitronyl Nitroxide [Na（NIT- 1＇-MeBzIm）3]ClO4： Synthesis and Crystal Structure

A novel complex [Na（NIT-1＇-MeBzIm）3]ClO4 （NIT-1＇-MeBzIm = 2-{2＇-[（1＇- methyl）benzimidazolyl]}-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide） has been prepared and structurally characterized by elemental analysis, IR spectra and X-ray diffraction methods. The title complex crystallizes in trigonal, space group P3 and Z = 2. Crystal data： C45H57ClN12NaO10, Mr = 984.47, a = 13.9411（8）, b = 13.9411（8）, c = 14.8622（16） A, γ= 120°, V= 2501.5（3） A^3, Dc = 1.307 g/cm^3, μ（MoKα） = 0.152 mm^-1, F（000） = 1038, R = 0.0637 and wR = 0.1813 for 1957 observed reflections with I 〉 2σ（I）. X-ray analysis reveals that the Na（I） ion is six-coordinated with three NIT-1＇-MeBzlm radicals. As we know, three radicals coordinating to the Na（I） ion in the main group by a chelate way is the first example. The Na（I） ion resides in a distorted octahedron with a facial configuration. Meanwhile, the intermolecular weak interactions result in a 2-D double layer conformation where the uncoordinated perchlorate anions are inserted in the packing space and take part in the H-bond interactions, and each complex is connected with six neighboring complexes and three perchlorate anions.     

Heavy-metal aromatic rings: cyclopentadienyl anion analogues Sn5(6-) and Pb5(6-) in the Zintl Phases Na8BaPb6, Na8BaSn6, and Na8EuSn6

The title compounds were prepared by direct reactions of the corresponding elements at high temperature. They are isostructural with each other (monoclinic, P2(1)/m, Z = 2; Na(8)BaPb(6), a = 13.116(4), b = 5.351(1), and c = 16.166(5) A, beta = 108.07(2) degrees; Na(8)BaSn(6), a = 12.897(4), b = 5.362(1), and c = 16.826(5) A, beta = 108.19(2) degrees; Na(8)EuSn(6), a = 12.912(2), b = 5.220(1), and c = 15.721(2) A, beta = 108.09(1) degrees ) and contain isolated, flat, and aromatic pentagonal rings of Sn(5)(6)(-) and Pb(5)(6)(-) as well as isolated anions of Sn(4)(-) and Pb(4)(-). According to four-probe conductivity measurements, the tin compounds, Na(8)BaSn(6) and Na(8)EuSn(6), are semiconducting with band gaps of 0.11 and 0.09 eV, respectively, and are therefore electronically balanced. Magnetic measurements show that Na(8)BaSn(6) is diamagnetic while Na(8)EuSn(6) is paramagnetic and undergoes two transitions at low temperatures.     

Theoretical study of Na(4p2P) + Na(3s2S) and Cd(5p3P0) + Na(3s2S) collisions and their role in the energy transfer between Cd.* and Na

We have computed the cross sections for the energy transfer process Cd(5p³P₀) + Na(3s²S) → Cd(5s¹S) + Na(4p²P) and for the state changing collision Na(4p²P) + Na(3s²S) → Na(3d²D) + Na(3s²S), based on theoretical interaction potentials for the NaCd and Na2 systems, respectively. Our calculations shed light on the interpretation of experiments with laser excited Na+Cd vapour mixtures [1]. It turns out that Cd(5p³P₀), in rapid equilibrium with the doorway state Cd(5p³P₁), efficiently transfers energy to Na, populating the 4p²P state. The collisions with ground state Na cause a very fast conversion of the 4p³P₁ to the 3d²D state, from which the strongest emission is observed.     

N-对R苯基氮杂15冠5八钼多酸钠超分子配合物的合成与结构

为研究大环化合物对客体分子的选择性, 合成了通式为[NaL(Et2O)]2Na2Mo8O26的三种新型N-对R苯基氮杂15冠5八钼多酸钠超分子配合物(其中L分别为: N-苯基氮杂15冠5、N-对氯苯基氮杂15冠5和N-对甲苯基氮杂15冠5), 进行了元素分析, 红外光谱与核磁共振等结构参数的表征, 对R基为CH3的标题配合物作了X射线四圆衍射测定, 该晶体属单斜晶系, 空间群为P21/a,a=1.4590(4)nm, b=1.3817(3)nm, c=1.7639(5)nm, β=112.67(2)°, V=3.281(1)nm^3, Mr=2021.3, Dc=2.11g/cm^3,μ=2.37mm^-^1, F(000)=2048, R=0.045和Rw=0.057, 与[Na.(DB18C6)(CH3OH)M6O19和[Na(DB24C8)]2M6O19进行比较,结果表明: 大环化合物不仅对客体金属离子有分子识别性, 而且对与之抗衡的多酸阴离子也具有影响。     

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.     

Na3PbII[B(O3POH)4]: an alkali-metal lead borophosphate with heterocubane-like units Na3PbO4

Na 3Pb (II)[B(O 3POH) 4] was synthesized under hydrothermal conditions. The crystal structure determination from single-crystal X-ray diffraction data ( I4 1/ a, Z = 4, a = 6.9182(8) A, c = 27.309 (3) A, V = 1307.0(3) A (3)) revealed the presence of [B(O 3POH) 4] (5-) oligomers and heterocubane-like units Na 3PbO 4 with mixed-occupied metal cation sites.     

Ionization induced relaxation in solvation structure: a comparison between Na(H2O)n and Na(NH3)n

The constant ionization potential for hydrated sodium clusters Na(H2O)n just beyond n=4, as observed in photoionization experiments, has long been a puzzle in violation of the well-known (n+1)(-1/3) rule that governs the gradual transition in properties from clusters to the bulk. Based on first principles calculations, a link is identified between this puzzle and an important process in solution: the reorganization of the solvation structure after the removal of a charged particle. Na(H2O)n is a prototypical system with a solvated electron coexisting with a solvated sodium ion, and the cluster structure is determined by a balance among three factors: solute-solvent (Na+-H2O), solvent-solvent (H2O-H2O), and electron-solvent (OH{e}HO) interactions. Upon the removal of an electron by photoionization, extensive structural reorganization is induced to reorient OH{e}HO features in the neutral Na(H2O)n for better Na+-H2O and H2O-H2O interactions in the cationic Na+(H2O)n. The large amount of energy released, often reaching 1 eV or more, indicates that experimentally measured ion signals actually come from autoionization via vertical excitation to high Rydberg states below the vertical ionization potential, which induces extensive structural reorganization and the loss of a few solvent molecules. It provides a coherent explanation for all the peculiar features in the ionization experiments, not only for Na(H2O)n but also for Li(H2O)n and Cs(H2O)n. In addition, the contrast between Na(H2O)n and Na(NH3)n experiments is accounted for by the much smaller relaxation energy for Na(NH3)n, for which the structures and energetics are also elucidated.     

Reactions of M[CH(SiMe3)2] (M = Na or K) with PhCN, and related chemistry

A number of metal complexes containing one of the following ligands: the 1-azaallyl [N(R)C(Ph)C(H)R]- ([triple bond]L-), the 1,3-diazaallyl([triple bond]LL'-) and the isomeric beta-diketiminate [{N(R)C(Ph)]}2CH]- ( identical with LL-) have been prepared (R = SiMe(3)). These are the crystalline compounds H(LL) (2), Na(LL) (3), [Na(LL)(thf)2] (4), Na(L) (6), [Na(mu-LL')]8 (7), [K(mu-L)(eta6-C6H6)]2 (8), [K(mu-LL')(thf)]2 (9), [K(thf)2(mu-LL)](infinity) (10) and [Ni(LL')2] (11). A new synthesis of Na[C(H)R2] (1) involved Hg[C(H)R2]2 and Na/Hg as reagents. The beta-diketimine 2 was obtained from Li(LL) and cyclopentadiene. Under different conditions compounds 3, 6 and 7 were isolated from 1 and benzonitrile, and compounds 8, 9 and 10 from K[C(H)R2] and PhCN. Complex 11 was derived from [Li(LL')]2 and [NiBr(2)(dme)]. The solution obtained from 1 + 2 PhCN in Et2O at ambient temperature was a mixture (5) of 3 (predominantly) and 7. The 1-azaallyl complex 8 has the ligand bound to the metal as the enamide, and this is also probably (NMR) the case for 6. The molecular structures of the crystalline complexes 7, 8 and 11 are presented; that of 10 was published earlier. Compound 7, a cyclooctamer, is particularly interesting, in that each LL'- ligand is bridging via one of its N atoms to two neighbouring sodium ions and is not only N,N'- but also (eta2-C[=]C)-chelating to one of them.     

Single crystal X-ray structure study of the Li(2-x)Na(x)Ni[PO4]F system

The new compounds Li(2-x)Na(x)Ni[PO(4)]F (x = 0.7, 1, and 2) have been synthesized by a solid state reaction route. Their crystal structures were determined from single-crystal X-ray diffraction data. Li(1.3)Na(0.7)Ni[PO(4)]F crystallizes with the orthorhombic Li(2)Ni[PO(4)]F structure, space group Pnma, a = 10.7874(3), b = 6.2196(5), c = 11.1780(4) ? and Z = 8, LiNaNi[PO(4)]F crystallizes with a monoclinic pseudomerohedrally twinned structure, space group P2(1)/c, a = 6.772(4), b = 11.154(6), c = 5.021(3) ?, β = 90° and Z = 4, and Na(2)Ni[PO(4)]F crystallizes with a monoclinic twinned structure, space group P2(1)/c, a = 13.4581(8), b = 5.1991(3), c = 13.6978(16) ?, β = 120.58(1)° and Z = 8. For x = 0.7 and 1, the structures contain NiFO(3) chains made up of edge-sharing NiO(4)F(2) octahedra, whereas for x = 2 the chains are formed of dimer units (face-sharing octahedra) sharing corners. These chains are interlinked by PO(4) tetrahedra forming a 3D framework for x = 0.7 and different Ni[PO(4)]F layers for x = 1 and 2. A sodium/lithium disorder over three atomic positions is observed in Li(1.3)Na(0.7)Ni[PO(4)]F structure, whereas the alkali metal atoms are well ordered in between the layers in the LiNaNi[PO(4)]F and Na(2)Ni[PO(4)]F structures, which makes both compounds of great interest as potential positive electrodes for sodium cells.     

Ca(1)(-)(x)Na(2)(x)Al(2)B(2)O(7): a structure with tunable density of Na(+) vacancies

A series of samples with the composition Ca(1)(-)(x)Na(2)(x)Al(2)B(2)O(7) (0 < x < or = 1) was investigated and a hexagonal structure with unusually large range of homogeneity (at least from x = 0.01 to 0.95) was revealed. The hexagonal phase consists of [Al(2)B(2)O(7)](infinity)(2)(-) lamellae stacked along the c axis, as in CaAl(2)B(2)O(7) and Na(2)Al(2)B(2)O(7). Nevertheless, the configuration and stacking sequence of the [Al(2)B(2)O(7)](infinity)(2)(-) lamellae are different in these three structures. In the hexagonal structure of Ca(1)(-)(x)()Na(2)(x)()Al(2)B(2)O(7), Ca and half Na cations (Na1) statistically occupy the same crystallographic site which is located between the [Al(2)B(2)O(7)](infinity)(2)(-) lamellae, the other half Na cations (Na2) distribute in the planes bisecting the [Al(2)B(2)O(7)](infinity)(2)(-) lamellae. Depending on the composition, the site occupation factor of Na2 site can vary in the same range as x, leading to a tunable density of Na(+) vacancies in the structure. The AlO(4) tetrahedra and BO(3) triangles in the structure tilt in appropriate ways to improve the bond valence sum of Na2 cations which are not sufficiently bonded to the anions.     

Plasma-assisted synthesis and properties of Na(3)N

Dark-blue sodium nitride, Na(3)N, was prepared by the reaction of metallic sodium or liquid Na-K alloy with plasma-activated nitrogen at low pressure. The compound crystallizes in the cubic anti-ReO(3)-type structure (space group Pm3m with a = 4.73301(6) Angstrom and Z = 1) according to powder and single-crystal X-ray diffraction data. Na(3)N decomposes above 104 degrees C into the elements, with DeltaH(f) estimated at +64(2) kJ/mol.     

Synthesis and Structure of [DB24C8)Na][Cd(SCN)3. Formation of a novel linear Cd...Cd...Cd chain with a mer-CdN3S3 coordination confirmation and new coiled [(DB24C8)Na]+ cation

We report herein a novel coordination solid, [(DB24C8)Na][Cd(SCN)3] (6) (DB24C8 denotes dibenzo-24-crown-8), which exhibits a new type of [Cd(SCN)3-]infinity chain with two unusual stereochemical characteristics: (1) a mer-CdN3S3 coordination and (2) a linear Cd chain with a Cd...Cd...Cd angle of 180 degrees. In addition, the [(DB24C8)Na]+ monocation adopts a new structural type-a coiled structure-for the combination of crown ether DB24C8 and alkali metal Na+. The title compound crystallizes in a monoclinic unit cell of C2/c space group symmetry with lattice parameters a = 16.110(8) A, b = 20.380(5) A, c = 11.01(1) A, beta = 119.87(3) degrees, and Z = 4. The arrangement of the [Cd(SCN)3-](infinity) chains in the crystal lattice in the title compound is approximately hexagonal, creating triangular channels which are filled with [(DB24C8)Na]+ monocations. It was previously reasoned by us that the coiled [(DB24C8)Na]+ monocation, which lacks inversion or mirror symmetries, should enhance the tendency for the formation of the noncentrosymmetric space group of the title crystal, making it a potential second-order nonlinear optical crystal. Interestingly, however, the title compound crystallizes in a centrosymmetric space group (C2/c) and gives rise to no second harmonic generation (SHG). Previously known [Cd(SCN)3-](infinity) chains adopt fac-CdN3S3 coordination and a zigzag Cd chain configuration with a Cd...Cd...Cd angle of 165 degrees. The zigzag chains can align in either parallel or antiparallel fashion, resulting in efficient or no SHG effects, respectively. The linear Cd.Cd.Cd chain configuration observed in the title compound, on the other hand, makes it indistinguishable between parallel and antiparallel alignments. It is concluded that, to ensure the formation of noncentrosymmetric space groups, it is necessary to employ optically pure chiral cations as spacers and/or controllers. Furthermore, to enhance the nonlinear optical responses, [Cd(SCN)3-]infinity chains with fac-CdN3S3 coordination and parallel alignments of the zigzag Cd chains should be used.     

First principles calculations of electronic structures and metal mobility of Na(x)Si(46) and Na(x)Si(34) clathrates

Energetics, geometry, electronic band structures, and charge transfer for Na(x)Si(46) and Na(x)Si(34) clathrates with different degrees of cavity filling by sodium, and the mobility of the Na atom inside the different cavities are studied using first principles density functional calculations within the generalized gradient approximation. The stabilization of the clathrate lattice and the cell volume variation upon the inclusion of Na (which appears to move easily in the larger cavities of Na(x)Si(34), thus justifying the experimental observations) are discussed in connection with the onset of the repulsion between Na and Si for distances shorter than approximately 3.4 A. For all degrees of filling of the different cavities examined we find that the electron population of the s orbitals in the partially ionized Na atoms increases with a decrease in the size of the cavity, and that the Na states contribute significantly to the density of states at the Fermi level and thus influence the properties of these compounds.     

Orientation of Na(3p) states excited in Na-He collisions

The orientation of Na(3p) states created in 3–13 keV Na(3s)-He collisions has been studied by the polarised photon-scattered particle coincidence technique at scattering angles corresponding to the impact-parameter range 1–2 a.u. In the standard geometry, at large impact parameters the excitation process exhibits a very high degree of orientation with about 90% of the Na(3p) states havingm ₁=?1. Strong reduction in this propensity is observed at impact parameters smaller than about 1.3 a.u., where a molecular curve crossing causes simultaneous He(n=2) excitation. In this region, also ionisation becomes important.     

17O solid-state NMR and first-principles calculations of sodium trimetaphosphate (Na3P3O9), tripolyphosphate (Na5P3O10), and pyrophosphate (Na4P2O7)

The assignment of high-field (18.8 T) (17)O MAS and 3QMAS spectra has been completed by use of first-principles calculations for three crystalline sodium phosphates, Na 3P 3O 9, Na 5P 3O 10, and Na 4P 2O 7. In Na 3P 3O 9, the calculated parameters, quadrupolar constant ( C Q), quadrupolar asymmetry (eta Q), and the isotropic chemical shift (delta cs) correspond to those deduced experimentally, and the calculation is mandatory to achieve a complete assignment. For the sodium tripolyphosphate Na 5P 3O 10, the situation is more complex because of the free rotation of the end-chain phosphate groups. The assignment obtained with ab initio calculations can however be confirmed by the (17)O{ (31)P} MAS-J-HMQC spectrum. Na 4P 2O 7 (17)O MAS and 3QMAS spectra show a complex pattern in agreement with the computed NMR parameters, which indicate that all of the oxygens exhibit very similar values. These results are related to structural data to better understand the influence of the oxygen environment on the NMR parameters. The findings are used to interpret those results observed on a binary sodium phosphate glass.     

Structural study of the Li(0.5)Na(0.5)MnFe2(PO4)3 and Li(0.75)Na(0.25)MnFe2(PO4)3 alluaudite phases and their electrochemical properties as positive electrodes in lithium batteries

The alluaudite lithiated phases Li(0.5)Na(0.5)MnFe(2)(PO(4))(3) and Li(0.75)Na(0.25)MnFe(2)(PO(4))(3) were prepared via a sol-gel synthesis, leading to powders with spongy characteristics. The Rietveld refinement of the X-ray and neutron diffraction data coupled with ab initio calculations allowed us for the first time to accurately localize the lithium ions in the alluaudite structure. Actually, the lithium ions are localized in the A(1) and A(1)' sites of the tunnel. M?ssbauer measurements showed the presence of some Fe(2+) that decreased with increasing Li content. Neutron diffraction revealed the presence of a partial Mn/Fe exchange between the two transition metal sites that shows clearly that the oxidation state of the element is fixed by the type of occupied site. The electrochemical properties of the two phases were studied as positive electrodes in lithium batteries in the 4.5-1.5 V potential window, but they exhibit smaller electrochemical reversible capacity compared with the non-lithiated NaMnFe(2)(PO(4))(3). The possibility of Na(+)/Li(+) ion deintercalation from (Na,Li)MnFe(2)(PO(4))(3) was also investigated by DFT+U calculations.     

Na*(3p)-Formation under grazing scattering of Na+-ions at an Al(111) surface

Excited Na*(3p)-atoms are observed in grazing surface-collision experiments with Na⁺-beams. Such atoms can be formed beyond a certain threshold velocity via resonant electron transfer between atomic and metallic conduction band levels due to motion of the atom relative to the surface of the metal (“kinematic resonance”). This mechanism is studied here theoretically employing two different techniques: the nonperturbative “Coupled Angular Mode” (CAM) method and the approximate “Transfer Hamiltonian” (TH) method. The calculated Na*(3p)-populations agree well with recent experimental results. Moreover, the complete density matrix of the Na*(3p)-subspace has been computed with the TH-method for ion-energies between 10 and 300 keV.