Syntheses, structures, and vibrational spectroscopy of the two-dimensional iodates Ln(IO3)3 and Ln(IO3)3(H2O) (LnYb, Lu)

The reaction of Lu³⁺ or Yb³⁺ and H₅IO₆ in aqueous media at 180 °C leads to the formation of Yb(IO₃)₃(H₂O) or Lu(IO₃)₃(H₂O), respectively, while the reaction of Yb metal with H₅IO₆ under similar reaction conditions gives rise to the anhydrous iodate, Yb(IO₃)₃. Under supercritical conditions Lu³⁺ reacts with HIO₃ and KIO₄ to yield the isostructural Lu(IO₃)₃. The structures have been determined by single-crystal X-ray diffraction. Crystallographic data are (MoKα, λ=0.71073 Å): Yb(IO₃)₃, monoclinic, space group P2₁/n, a=8.6664(9) Å, b=5.9904(6) Å, c=14.8826(15) Å, β=96.931(2)°, V=766.99(13), Z=4, R(F)=4.23% for 114 parameters with 1880 reflections with I>2σ(I); Lu(IO₃)₃, monoclinic, space group P2₁/n, a=8.6410(9), b=5.9961(6), c=14.8782(16) Å, β=97.028(2)°, V=765.08(14), Z=4, R(F)=2.65% for 119 parameters with 1756 reflections with I>2σ(I); Yb(IO₃)₃(H₂O), monoclinic, space group C2/c, a=27.2476(15), b=5.6296(3), c=12.0157(7) Å, β=98.636(1)°, V=1822.2(2), Z=8, R(F)=1.51% for 128 parameters with 2250 reflections with I>2σ(I); Lu(IO₃)₃(H₂O), monoclinic, space group C2/c, a=27.258(4), b=5.6251(7), c=12.0006(16) Å, β=98.704(2)°, V=1818.8(4), Z=8, R(F)=1.98% for 128 parameters with 2242 reflections with I>2σ(I). The f elements in all of the compounds are found in seven-coordinate environments and bridged with monodentate, bidentate, or tridentate iodate anions. Both Lu(IO₃)₃(H₂O) and Yb(IO₃)₃(H₂O) display distinctively different vibrational profiles from their respective anhydrous analogs. Hence, the Raman profile can be used as a complementary diagnostic tool to discern the different structural motifs of the compounds.     

Inverse Perovskites (Eu3O)E with E = Sn,In – Preparation,Crystal Structures and Physical Properties

The cubic inverse Perovskites (Eu₃O)In and (Eu₃O)Sn were prepared from the metals and Eu₂O₃ or SnO₂, respectively. For (Eu₃O)In the crystal structure analysis was performed on single crystal X‐ray diffraction data (space group , a = 512.79(3) pm, Z = 1, R_gt(F) = 0.022, wR(F²) = 0.044). The data indicated full occupancy on all sites and a fully ordered structure. According to magnetic susceptibility measurements and X‐ray absorption spectroscopic data at the Eu L_III edge both compounds contain europium in the 4f⁷ (Eu²⁺) electronic state. (Eu₃O)In orders ferromagnetically at 185(5) K, (Eu₃O)Sn shows antiferromagnetic order at 31.4(2) K. Both compounds behave as metallic conductors in electrical resistivity measurements. However, (Eu₃O)In may be classified a metal, while (Eu₃O)Sn is more likely a heavily doped degenerated semiconductor or semimetal according to the absolute values of the resistivity.     

Synthesis, crystal structure and mono-dimensional thallium ion conduction of TlFe0.22Al0.78As2O7

A new solid solution TlFe_0.22Al_0.78As₂O₇ has been synthesized by a solid-state reaction. The structure of the title compound has been determined from a single-crystal X-ray diffraction and refined to final values of the reliability factors: R(F²)=0.030 and wR(F²)=0.081 for 1343 independent reflections with I>2σ(I). It crystallizes in the triclinic space group P-1, with a=6.296(2) Å, b=6.397(2) Å, c=8.242(2) Å, α=96.74(2)°, β=103.78(2)°, γ=102.99(3)°, V=309.0(2) Å³ and Z=2. The structure can be described as a three-dimensional framework containing (Fe/Al)O₆ octahedra connected through As₂O₇ groups. The metallic units and diarsenate groups share oxygen corners to form a three-dimensional framework with interconnected tunnels parallel to the a, b and c directions, where Tl⁺ cations are located. The ionic conductivity measurements are performed on pellets of the polycrystalline powder. At 683 K, The conductivity value is 5.23×10⁻⁶ S cm⁻¹ and the ionic jump activation energy is 0.656 eV. The bond valence analysis reveals that the ionic conductivity is ensured by Tl⁺ along the [001] direction.     

Manipulating the Through‐Space Spin–Spin Interaction of Organic Radicals in the Confined Cavity of a Self‐Assembled Cage

We show a new approach to manipulating the through‐space spin–spin interaction by utilizing the confined cavity of a self‐assembled M₆L₄ coordination cage. The coordination cage readily encapsulates stable organic radicals in solution, which brings the spin centers of the radicals closer to each other. In sharp contrast to the fact that the radical in solution in the absence of the cage is in a doublet state, in the presence of the cage through‐space spin–spin interaction is induced through cage‐encapsulation effects in solution as well as in the solid state, resulting in the triplet state of the complex. These results were confirmed by ESR spectroscopy and X‐ray crystallography. The quantity of triplet species generated by encapsulation in the cage increases with increasing affinity of the radicals to the cage. We estimated the affinity between several types of guests and the cage in solution by cyclic voltammetry. We also demonstrate that the through‐space interaction of organic radicals within the self‐assembled coordination cage can be controlled by external stimuli such as heat or pH.     

Homo- and heterometallic [2x2] grid arrays containing RuII, OsII, and FeII subunits and their mononuclear RuII and OsII precursors: synthesis, absorption spectra, redox behavior, and luminescence properties

The absorption spectra, redox behavior, and luminescence properties (both at 77 K in rigid matrices and at room temperature in fluid solution) of a series of [2x2] molecular grids have been investigated. The latter were prepared either by means of sequential self-assembly, or by a stepwise protection/deprotection procedure, and are based on a ditopic hexadentate ligand 1 in which two terpyridine-like binding sites are fused together in a linear arrangement. The molecular grids studied include the homometallic species [[Fe(1)](4)](8+) (Fe(2)Fe(2)), and the heterometallic species [[Ru(1)](2)[Fe(1)](2)](8+) (Ru(2)Fe(2)) and [[Os(1)](2)[Fe(1)](2)](8+) (Os(2)Fe(2)). For comparison purposes, the properties of the mononuclear complexes [Ru(1)(2)](2+) (1-Ru) and [Os(1)(2)](2+) (1-Os) have been studied. All these compounds exhibit very intense absorption bands in the UV region (epsilon in the 10(5)-10(6) M(-1) cm(-1) range, attributed to spin-allowed ligand-centered (LC) transitions), as well as intense metal-to-ligand charge-transfer (MLCT) transitions (epsilon in the 10(4)-10(5) M(-1) cm(-1) range) that extend to the entire visible region. The mononuclear species 1-Ru and 1-Os exhibit relatively intense luminescence, both in acetonitrile at room temperature (tau=59 and 18 ns, respectively) and in butyronitrile rigid matrices at 77 K. In contrast, the tetranuclear molecular grids do not exhibit any luminescence, either at room temperature or at 77 K. This is attributed to fast intercomponent energy transfer from the Ru- or Os-based subunits to the low-lying metal-centered (MC) levels involving the Fe(II) centers, which leads to fast radiationless decay. The redox behavior of the compounds is characterized by several metal-centered oxidation and ligand-centered reduction processes, most of them reversible in nature (as many as twelve for Fe(2)Fe(2)). Detailed assignment of each redox process has been made, and it is apparent that these systems can be viewed as multilevel molecular electronic species capable of reversibly exchanging a number of electrons at accessible and predetermined potentials. Furthermore, it is shown that the electronic interaction between specific subunits depends on their location in the structure and on the oxidation states of the other components.     

Divalent transition metal phosphonates with new structure containing hydrogen-bonded layers of phosphonate anions

A series of divalent transition metal phosphonates containing hydrogen-bonded layers of phosphonate anions, namely [M(phen)₃]·C₆H₅PO₃·11H₂O [M=Co(1), Ni(2), Cu(3)] and [Cd(phen)₃]·C₆H₅PO₃H·Cl·7H₂O (4) have been synthesized, structurally characterized by single-crystal X-ray diffraction method. These compounds all crystallize in the triclinic system, space group P-1. The lattice parameters are a=12.1646(5), b=12.4155(6), c=15.4117(10) Å, α=78.216(2), β=79.735(3), γ=77.8380(3)°, V=2205.1(2) Å³, Z=2 for 1; a=12.097(2), b=12.606(3), c=15.742(3) Å, α=76.66(3), β=80.04(3), γ=77.75(3)°, V=2263.4(8) Å³, Z=2 for 2; a=12.058(2), b=12.518(3), c=15.781(3) Å, α=77.77(3), β=80.02(3), γ=77.91(3)°, V=2255.5(8) Å³, Z=2 for 3 and a=12.47680(10), b=12.6693(2), c=16.1504(3) Å, α=82.600(1), β=71.122(1), γ=77.355(1)°, V=2352.37(6) Å³, Z=2 for 4. All structures are refined by full-matrix least-squares methods [for 1, R1=0.0602 using 6458 independent reflections with I>2σ(I); for 2, R1=0.0632 using 4657 independent reflections with I>2σ(I); for 3, R1=0.0634 using 6221 independent reflections with I>2σ(I); for 4, R1=0.0400 using 7930 independent reflections with I>2σ(I)]. In the crystal structures, the phenylphosphonate anions and water molecules are hydrogen-bonded to form layers, and there exist the cationic species [M(phen)₃]²⁺ between the adjacent layers of anions and water. Luminescence, thermal analysis as well as IR spectroscopic studies are also presented.     

Synthesis and NMR spectroscopic investigation of salts containing the novel [Au(CF3)nX4−n] (n=4-1, X=F, CN, Cl) anions

First examples for the syntheses of trifluoromethyl transition metal complexes by conversion of a cyano into a trifluoromethyl ligand are described. The fluorination of [][Au(CN)₄] with ClF in CH₂Cl₂ leads to the formation of a mixture of gold complexes of the type [AuF_xCl_y(CF₃)_4−x−y]⁻ (x=0-4, y=0-2). Ligand exchange reactions of [AuF_xCl_y(CF₃)_4−x−y]⁻ (x=0-4, y=0-2) with (CH₃)₃SiY (Y=Cl, CN) are performed resulting in anions of the type [AuY_x(CF₃)_4−x]⁻ (x=0-4). All products are characterised by - and NMR spectroscopy.     

Chemical Modification of Silica Gels

Highly porous pure and polyethyleneglycol (PEG)-doped silica gels have been prepared from tetraethyl orthosilicate (TEOS) in ethanol using NH₄OH base-catalysis. Addition of PEG to the SiO₂-system increases the average particle size and most frequent pore diameter of the resultant gels while their total surface area decreases. The viscosity of the sol increases with PEG concentration and passes through a maximum with increasing molecular weight at PEG 200. Results obtained indicate a definite interaction of the polymer with SiO₂ and that this interaction is not as a result of direct formation of Si– O– C linkage, but is more likely to be due to hydrogen bonding between the hydrated PEG and the Si– O– Si network. Structure-process correlations are considered.     

用近红外光谱仪快速测定调和汽油中芳烃、烯烃的含量

介绍了带有CCD检测器的近红光普仪在调和汽油分析中的应用，并与标准测定方法测定的数据对比，验证了近红外光谱法测定汽油性质的可靠性，同时表明该方法具有分析速度快，重现性好等特点。     

钆(Ⅲ)-钙试剂络合物吸附波研究

在含有 0 .1 0 mol/L KCl,p H=1 0 .2的 NH3- NH4 Cl缓冲溶液中 ,用线性扫描示波极谱法测得 Gd( ) - Cal- red络合物有一灵敏的导数波 ,峰电位在 - 0 .84V,峰电流与钆 ( )的浓度在 1 .0× 1 0 - 7～ 5 .0× 1 0 - 6 mol/L范围内呈线性关系 ,检出限达1 .0× 1 0 - 7mol/L ;另外 ,试剂本身在 - 0 .61 V有导数极谱波 ,该波的峰电流随钆( )的浓度增加而降低 ,也具有一定的线性关系