Syntheses and characterization of nine quaternary uranium chalcogenides among the compounds A2M3UQ6 (A = K, Rb, Cs; M = Pd, Pt; Q = S, Se)

Nine compounds from the series A(2)M(3)UQ(6) (A = K or Rb or Cs; M = Pd or Pt; Q = S or Se) were synthesized by reacting U, M, and Q in ACl or A(2)Q(x) fluxes. These compounds crystallize with eight formula units in the NaBa(2)Cu(3)O(6) structure type, in space group Fmmm of the orthorhombic system. The structure contains hexagons formed from six edge-sharing square-planar coordinated M atoms, which in turn edge-share with trigonal-prismatically coordinated U atoms, forming layers along (010). These layers are separated by A atoms. Electrical resistivity measurements along the [100] direction of Rb(2)Pd(3)US(6) show typical semiconductor behavior. Magnetic susceptibility measurements on Rb(2)Pd(3)US(6) display marked magnetic anisotropy and unusually low magnetic moments owing to crystalline electric field effects.     

Syntheses and structural characterization of new mixed-valent tellurium oxides, a4[te5(6+)te(3)4+]o23 (a=rb and k)

Two new isostructural mixed-valent tellurium oxides, A4[Te(5)6+Te3(4+)]O23 [A=Rb and K], have been synthesized by solid-state reactions and characterized by X-ray diffraction and infrared spectroscopy. Compound could be prepared by hydrothermal reaction as well. These compounds, as determined from the single-crystal X-ray structure of, consist of corrugated [Te6O23] layers, built from corner-connected TeO6 octahedra and TeO5 square pyramids. These layers are connected to one another by tetravalent telluriums, having square-pyramidal and disphenoid geometries. Both compounds crystallize in the orthorhombic space group Pna2(1) (33) with Z=4 and have the following unit cell parameters: For 1, a=19.793(4), b=14.664(4), and c=7.292(4) A. For 2, a=19.573(3), b=14.448(2), and c=7.273(8) A.     

Syntheses and structures of the arylaluminum chalcogenides (ArAlE)2 (Ar = 2-(NEt2CH2)-6-MeC6H3, E = Se; Ar = 2,6-(NEt2CH2)2C6H3, E = Se, Te)

Two intramolecular stabilized arylaluminum dihydrides, (2-(NEt2CH2)-6-MeC6H3)AlH2 (1) and (2,6-(NEt2CH2)2C6H3)AlH2 (2), were prepared by reducing the corresponding dichlorides with an excess of LiAlH4 in diethyl ether. Reactions of 1 and 2 with elemental selenium afforded the dimeric arylaluminum selenides [(2-(NEt2CH2)-6-MeC6H3)AlSe]2 (3) and [(2,6-(NEt2CH2)2C6H3)AlSe]2 (4). Reaction of 2 with metallic tellurium gave the dimeric arylaluminum telluride [(2,6-(NEt2CH2)2C6H3)AlTe]2 (5). The possible reaction pathway is discussed, and molecular structures determined by single-crystal X-ray analyses are presented for 3 and 5.     

Geometrical and electronic structures of Au(m)Ag(n) (2 < or = m + n < or = 8)

The structural and electronic properties of Au(m)Ag(n) binary clusters (2 < or = m + n < or = 8) have been investigated by density functional theory with relativistic effective core potentials. The results indicate that Au atoms tend to occupy the surface of Au(m)Ag(n) clusters (n > or = 2 and m > or = 2). As a result, segregation of small or big bimetallic clusters can be explained according to the atomic mass. The binding energies of the most stable Au(m)Ag(n) clusters increase with increasing m+n. The vertical ionization potentials of the most stable Au(m)Ag(n) clusters show odd-even oscillations with changing m+n. The possible dissociation channels of the clusters considered are also discussed.     

m -Terphenyl derivative of titanium(III): Cp2TiR (Cp=C5H5; R =2,6-(4-MeC6H4)2C6H3)

The title compound, Cp₂TiR (Cp=C₅H₅; R=2,6-(4-MeC₆H₄)₂C₆H₃), 1, was prepared by reaction of RLi with [Cp₂TiCl]₂. Compound 1 was characterized by elemental analysis, EPR, and single crystal X-ray crystallography. The title compound crystallizes in the monoclinic space group C2/c with the following unit cell dimensions: a=11.1466(7) Å, b=16.4429(11) Å, c=13.0786(8) Å; b=106.2040(10)^°;V=2301.9(3) ų. The EPR spectrum of 1 displays two signals, a high field signal at g=1.979 and a lower field signal at g=1.959. Significantly, 1 is a sterically encumbered m-terphenyl-stabilized trivalent titanocene paramagnetic complex and may be a practical one-electron reducing reagent.     

[C(AuPH3)m]n+ (m=4-6; n=0-2)成键性质和稳定性研究

用MP2/LanL2DZ方法优化C(AuPH3)4[1a(C4v); 1b(Td)], [C(AuPH3)5]+[2a(C3h); 2b(Cs)]以及[C(AuPH3)6}]2+[3a(C2h); 3b(C2v)]的结构, 得到的几何参数与实验值相符. MP2水平下的自然键轨道(Natural bond orbitals, NBO)分析表明, Au具有d(sp)杂化性质, 其中(sp)具有s-p混合的轨道性质; 沿C-Au辐射方向形成的σ键和切向Au-Au之间的弱吸引相互作用使得整个分子稳定. 化合物1a, 2和3具有2或3个二电子三中心键, 表明该类化合物具有与传统C化学不同的电子结构和立体化学构型.     

Aminotroponiminatogermaacid halides with a ge(e)x moiety (e = s, se; x = f, cl)

Fluorination of aminotroponiminate (ATI) ligand-stabilized germylene monochloride [(t-Bu)(2)ATI]GeCl (1) with CsF gave the aminotroponiminatogermylene monofluoride [(t-Bu)(2)ATI]GeF (2). Oxidative addition reaction of compound 2 with elemental sulfur and selenium led to isolation of the corresponding germathioacid fluoride [(t-Bu)(2)ATI]Ge(S)F (3) and germaselenoacid fluoride [(t-Bu)(2)ATI]Ge(Se)F (4), respectively. Similarly, reaction of aminotroponiminatogermylene monochloride [(i-Bu)(2)ATI]GeCl (9) with elemental sulfur and selenium gave the aminotroponiminatogermathioacid chloride [(i-Bu)(2)ATI]Ge(S)Cl (11) and aminotroponiminatogermaselenoacid chloride [(i-Bu)(2)ATI]Ge(Se)Cl (12), respectively. Compound 9 has been prepared through a multistep synthetic route starting from 2-(tosyloxy)tropone 5. All compounds (2-4 and 6-12) were characterized through the multinuclear NMR spectroscopy, and single-crystal X-ray diffraction studies were performed on compounds 2, 4, and 8-12. The germaselenoacid halide complexes 4 and 12 showed doublet (-142.37 ppm) and singlet (-213.13 ppm) resonances in their (77)Se NMR spectra, respectively. Germylene monohalide complexes 2 and 9 have a germanium center in distorted trigonal pyramidal geometry, whereas a distorted tetrahedral geometry is seen around the germanium center in germaacid halide complexes 4, 11, and 12. The length of the Ge═E bond in germathioacid chloride (11) and germaselenoacid halide (4 and 12) complexes is 2.065(1) and 2.194(av) ?, respectively. Theoretical studies (based on the DFT methods) on complexes 4, 11, and 12 reveal the nature of the Ge═E multiple bond in these germaacid halide complexes with computed Wiberg bond indices (WBI) being 1.480, 1.508, and 1.541, respectively.     

Synthesis and characterization of [PtIn6](GeO4)2O and its solid solution [PtIn6](GaO4)(2-x)(GeO4)xOx/2 (0 < or = x < or = 2): gradual color change of the solid solution from black (x = 0) to yellow (x = 2) as a consequence of quantum dot effect

A new phase [PtIn6](GeO4)2O, a filled variant of [PtIn6](GaO4)2, and the solid solution [PtIn6](GaO4)(2-x)(GeO4)xOx/2 (0 < or = x < or = 2) were prepared and characterized. Single-crystal structure refinements show that [PtIn6](GeO4)2O is isotypic with the mineral, sulfohalite Na6FCl(SO4)2, and crystallizes in the space group Fmm (Z = 4) with a = 1006.0(1) pm. The building units of [PtIn6](GeO4)2O are isolated [PtIn6]10+ octahedra and (GeO4)4- tetrahedra, and the isolated O2- ions occupy the centers of the In6 octahedra made up of six adjacent PtIn6 octahedra. The lattice parameter of the solid solution [PtIn6](GaO4)(2-x)(GeO4)xOx/2 (0 < or = x < or = 2) varies gradually from a = 1001.3(1) pm at x = 0 to a = 1006.0(1) pm at x = 2, and the color of the solid solution changes gradually from black (x = 0) to red (x = 1) to yellow (x = 2). The cause for the gradual color change was examined by performing density functional theory electronic structure calculations for the end members [PtIn6](GaO4)2 and [PtIn6](GeO4)2O. Our analysis indicates that an oxygen atom at the center of a In6 octahedron cuts the In 5p/In 5p bonding interactions between adjacent [PtIn6]10+ octahedra thereby raising the bottom of the conduction bands, and the resulting quantum dot effect is responsible for the color change.     

Ternary arsenides a(2)zn(5)as(4) (a = k, rb): zintl phases built from stellae quadrangulae

Stoichiometric reaction of the elements at high temperature yields the ternary arsenides K(2)Zn(5)As(4) (650 °C) and Rb(2)Zn(5)As(4) (600 °C). They adopt a new structure type (Pearson symbol oC44, space group Cmcm, Z = 4; a = 11.5758(5) ?, b = 7.0476(3) ?, c = 11.6352(5) ? for K(2)Zn(5)As(4); a = 11.6649(5) ?, b = 7.0953(3) ?, c = 11.7585(5) ? for Rb(2)Zn(5)As(4)) with a complex three-dimensional framework of linked ZnAs(4) tetrahedra generating large channels that are occupied by the alkali-metal cations. An alternative and useful way of describing the structure is through the use of stellae quadrangulae each consisting of four ZnAs(4) tetrahedra capping an empty central tetrahedron. These compounds are Zintl phases; band structure calculations on K(2)Zn(5)As(4) and Rb(2)Zn(5)As(4) indicate semiconducting behavior with a direct band gap of 0.4 eV.     

Monophosphate tungsten bronzes with pentagonal tunnels (PO2)4(WO3)2m: Structure of two even-m members P4W12O44 (m = 6) and P4W16O56 (m = 8)

Crystals of P₄W₁₂O₄₄ and P₄W₁₆O₅₆ have been synthesized. They are orthorhombic, space group P2₁2₁2₁ with a = 5.2927(7), b = 6.5604(7), c = 23.549(3)Å for P₄W₁₂O₄₄ and a = 5.2943(5), b = 6.5534(4), c = 29.700(4)Å for P₄W₁₆O₅₆. Structures were solved by the heavy-atom method and refined to R = 0.033 (R_w = 0.044) with 2031 independent reflections for P₄W₁₂O₄₄ and R = 0.043 (R_w = 0.052) with 2272 independent reflections for P₄W₁₆O₅₆. The structures are related to that of P₄W₈O₃₂ and can be described by the association of zig-zag chains of octahedra and tetrahedra. The members of the series (PO₂)₄(WO₃)_2m differ from one another by the length of the links in the chains of polyhedra. Pentagonal tunnels and O₁₈ cages are formed at the junction between the ReO₃-type slabs and the slices of PO₄ tetrahedra. The surroundings of P and W have been studied and compared with those of other phosphate tungsten bronzes; the relation with the apparent oxidation state of tungsten is discussed.     

Syntheses,structures, and characterization of new lead(II)-tellurium(IV)-oxide halides: Pb3Te2O6X2 and Pb3TeO4X2 (X = Cl or Br)

The syntheses, structures, and characterization of four new lead(II)-tellurium(IV)-oxide halides, Pb(3)Te(2)O(6)X(2) and Pb(3)TeO(4)X(2) (X = Cl or Br) are reported. The materials are synthesized by solid-state techniques, using Pb(3)O(2)Cl(2) or Pb(3)O(2)Br(2) and TeO(2) as reagents. The compounds have three-dimensional structural topologies consisting of lead-oxide halide polyhedra connected to tellurium oxide groups. In addition, the Pb(2+) and Te(4+) cations are in asymmetric coordination environments attributable to their stereoactive lone pair. We also demonstrate that Pb(3)Te(2)O(6)X(2) and Pb(2)TeO(4)X(2) can be interconverted reversibly through the loss or addition of TeO(2). X-ray data: Pb(3)Te(2)O(6)Cl(2), monoclinic, space group C2/m (No. 12), a = 16.4417(11) A, b = 5.6295(4) A, c = 10.8894(7) A, beta = 103.0130(10) degrees, Z = 4; Pb(3)Te(2)O(6)Br(2), monoclinic, space group C2/m (No. 12), a = 16.8911(8) A, b = 5.6804(2) A, c = 11.0418(5) A, beta = 104.253(2) degrees, Z = 4; Pb(3)TeO(4)Cl(2), orthorhombic, space group Bmmb (No. 63), a = 5.576(1) A, b = 5.559(1) A, c = 12.4929(6) A, Z = 4; Pb(3)TeO(4)Br(2), orthorhombic, space group Bmmb (No. 63), a = 5.6434(4) A, b = 5.6434(5) A, c = 12.9172(6) A, Z = 4.     

[M6Om(C25N4H18)n]2-(M=W, Mo; n=1, 2; m=17,18)的二阶非线性光学性质的理论研究

运用密度泛函理论(DFT)的BP86方法, 对[M6Om(C25N4H18)n]2-(M=W, Mo; n=1, 2; m=17,18)进行了几何结构优化, 其中Mo系列结构化合物优化的几何结构与实验值吻合较好. 在净电场为零的条件下, 运用DFT/LB94方法计算了体系的二阶非线性光学系数β值: 体系1和2的βvec值分别为154.4×10-30和124.8×10-30 esu. 表明它们具有较大的二阶非线性光学系数, 且Mo系列比W系列的β值大. 而体系3和4的βvec值分别为218.0×10-30和191.8×10-30 esu. 体系3和4的βvec值分别比体系1和2的大, 表明增加给体的数目有利于提高NLO响应, 但都小于它们的2倍.     

Iron-arylimide clusters [Fe(m)()(NAr)(n)Cl(4)](2)(-) (m,n = 2, 2; 3, 4; 4, 4) from a ferric amide precursor: synthesis,characterization, and comparison to Fe-S chemistry

Tetrahedral FeCl[N(SiMe(3))(2)](2)(THF) (2), prepared from FeCl(3) and 2 equiv of Na[N(SiMe(3))(2)] in THF, is a useful ferric starting material for the synthesis of weak-field iron-imide (Fe-NR) clusters. Protonolysis of 2 with aniline yields azobenzene and [Fe(2)(mu-Cl)(3)(THF)(6)](2)[Fe(3)(mu-NPh)(4)Cl(4)] (3), a salt composed of two diferrous monocations and a trinuclear dianion with a formal 2 Fe(III)/1 Fe(IV) oxidation state. Treatment of 2 with LiCl, which gives the adduct [FeCl(2)(N(SiMe(3))(2))(2)](-) (isolated as the [Li(TMEDA)(2)](+) salt), suppresses arylamine oxidation/iron reduction chemistry during protonolysis. Thus, under appropriate conditions, the reaction of 1:1 2/LiCl with arylamine provides a practical route to the following Fe-NR clusters: [Li(2)(THF)(7)][Fe(3)(mu-NPh)(4)Cl(4)] (5a), which contains the same Fe-NR cluster found in 3; [Li(THF)(4)](2)[Fe(3)(mu-N-p-Tol)(4)Cl(4)] (5b); [Li(DME)(3)](2)[Fe(2)(mu-NPh)(2)Cl(4)] (6a); [Li(2)(THF)(7)][Fe(2)(mu-NMes)(2)Cl(4)] (6c). [Li(DME)(3)](2)[Fe(4)(mu(3)-NPh)(4)Cl(4)] (7), a trace product in the synthesis of 5a and 6a, forms readily as the sole Fe-NR complex upon reduction of these lower nuclearity clusters. Products were characterized by X-ray crystallographic analysis, by electronic absorption, (1)H NMR, and M?ssbauer spectroscopies, and by cyclic voltammetry. The structures of the Fe-NR complexes derive from tetrahedral iron centers, edge-fused by imide bridges into linear arrays (5a,b; 6a,c) or the condensed heterocubane geometry (7), and are homologous to fundamental iron-sulfur (Fe-S) cluster motifs. The analogy to Fe-S chemistry also encompasses parallels between Fe-mediated redox transformations of nitrogen and sulfur ligands and reductive core conversions of linear dinuclear and trinuclear clusters to heterocubane species and is reinforced by other recent examples of iron- and cobalt-imide cluster chemistry. The correspondence of nitrogen and sulfur chemistry at iron is intriguing in the context of speculative Fe-mediated mechanisms for biological nitrogen fixation.     

Syntheses and X-ray diffraction, photochemical, and optical characterization of Cu2SixSn1-xS3 (0.4 < or = x < or = 0.6) for photovoltaic applications

The study of the pseudobinary system Cu(2)SnS(3-)Cu(2)SiS(3) shows that a solid solution (Cu(2)Si(x)Sn(1-x)S(3)) exists in the range 0.4 < or = Si/(Sn+Si) < or = 0.6. Based on diffuse reflectance and photoelectrochemical measurements these compounds show potential as absorber materials for photovoltaic devices. The compounds were prepared at 850 degrees C from copper sulfide, silicon, tin, and sulfur and were analyzed with single-crystal (for x approximately 0.40) and powder diffraction techniques. Optical band gaps of 1.25, 1.35, and 1.45 eV were observed for the three compositions x = 0.39, 0.48, and 0.61; cathodic photocurrent occurring is significant.     

Hydrogen-bonded networks in ethanol proton wires: IR spectra of (EtOH)qH+-Ln clusters (L = Ar/N2, q < or = 4, n < or = 5)

Isolated and microsolvated protonated ethanol clusters, (EtOH)qH+-Ln with L = Ar and N2, are characterized by infrared photodissociation (IRPD) spectroscopy in the 3 microm range and quantum chemical calculations. For comparison, also the spectrum of the protonated methanol dimer, (MeOH)2H+, is presented. The IRPD spectra carry the signature of H-bonded (EtOH)qH+ chain structures, in which the excess proton is either strongly localized on one or (nearly) equally shared between two EtOH molecules, corresponding to Eigen-type ion cores (EtOH2+ for q = 1, 3) or Zundel-type ion cores (EtOH-H+-HOEt for q = 2, 4), respectively. In contrast to neutral (EtOH)q clusters, no cyclic (EtOH)qH+ isomers are detected in the size range investigated (q < or = 4), indicative of the substantial impact of the excess proton on the properties of the H-bonded ethanol network. The acidity of the two terminal OH groups in the (EtOH)qH+ chains decreases with the length of the chain (q). Comparison between (ROH)qH+ with R = CH3 and C2H5 shows that the acidity of the terminal O-H groups increases with the length of the aliphatic rest (R). The most stable (EtOH)qH+-Ln clusters with n < or = 2 feature intermolecular H-bonds between the inert ligands and the two available terminal OH groups of the (EtOH)qH+ chain. Asymmetric microsolvation of (EtOH)qH+ with q = 2 and 4 promotes a switch from Zundel-type to Eigen-type cores, demonstrating that the fundamental structural motif of the (EtOH)qH+ proton wire sensitively depends on the environment. The strength of the H-bonds between L and (EtOH)qH+ is shown to provide a rather sensitive probe of the acidity of the terminal OH groups.     

Preferred bonding motif for indium aminoethanethiolate complexes: structural characterization of (Me2NCH2CH2S)2InX/SR (X = Cl, I; R = 4-MeC6H4, 4-MeOC6H4)

The metathesis reaction of InCl3 with Me2NCH2CH2SNa or the redox reaction of indium metal with elemental iodine and the disulfide (Me2NCH2CH2S)2 yield the indium bis(thiolate) complexes (Me2NCH2CH2S)2InX [X = Cl (3) and I (4)], respectively. Compounds 3 and 4 may be further reacted with the appropriate sodium thiolate salts to afford the heteroleptic tris(thiolate) complexes (Me2NCH2CH2S)2InSR [R = 4-MeC6H4 (5), 4-MeOC6H4 (6), and Pr (7)]. Reaction of 2,6-Me2C6H3SNa with 4 affords (Me2NCH2CH2S)2InS(2,6-Me2C6H3) (8), while no reaction is observed with 3, suggesting a greater reactivity for 4. All isolated compounds were characterized by elemental analysis, melting point, and Fourier transform IR and 1H and 13C{1H} NMR spectroscopies. X-ray crystallographic analyses of 3-6 show a bicyclic arrangement and a distorted trigonal-bipyramidal geometry for In in all cases. The two sulfur and one halogen (3 and 4) or three sulfur (5 and 6) atoms occupy equatorial positions, while the nitrogen atoms of the chelating (dimethylamino)ethanethiolate ligands occupy the axial positions. The metric parameters of the (Me2NCH2CH2S)2In framework were found to change minimally upon variation of the X/SR ligand, while the solubility of the corresponding compounds in organic solvents varied greatly. 1H NMR studies in D2O showed that 6 and 7 react slowly with an excess of the tripeptide l-glutathione and that the rate of reaction is affected by the pendant thiolate ligand -SR.