Polyoxometalate-based eight-connected self-catenated network and fivefold interpenetrating framework

Two entangled compounds [(bpy)₆Cu^I₆Cl₃(Mo^VW₅O₁₉)] (1) and [(bpy)₇Cu^I₇Cl₂(BW₁₂O₄₀)]·H₂O (2) (bpy=4,4′-bipyridine), have been successfully synthesized under hydrothermal conditions and characterized by element analysis, IR spectroscopy, thermal gravimetric analysis, X-ray photoelectron spectroscopy, and single crystal X-ray diffraction analyses. Compound 1 represents the first eight-connected self-penetrating network constructed from cuprous chloride clusters [Cu₆Cl₃] and Lindquist-type polyoxoanions. Compound 2 exhibits an interesting fivefold interpenetrating network consisting of Keggin polyoxoanions and Cu⁺-metal-organic framework. Crystal data of the two compounds are following: 1, triclinic, , a=11.502(2) Å, b=13.069(3) Å, c=13.296(3) Å, α=90.55(3)°, β=113.74(3)°, γ=110.48(3)°, Z=1; 2, triclinic, , a=12.341(3) Å, b=13.119(3) Å, c=15.367(3) Å, α=99.12(3)°, β=90.53(3)°, γ=104.49(3)°, Z=1.     

Phase transitions in K3AlF6

Phase transitions in the elpasolite-type K₃AlF₆ complex fluoride were investigated using differential scanning calorimetry, electron diffraction and X-ray powder diffraction. Three phase transitions were identified with critical temperatures , and . The α-K₃AlF₆ phase is stable below T₁ and crystallizes in a monoclinic unit cell with a=18.8588(2)Å, b=34.0278(2)Å, c=18.9231(1)Å, β=90.453(1)° (a=2a_c−c_c, b=4b_c, c=a_c+2c_c; a_c, b_c, c_c—the basic lattice vectors of the face-centered cubic elpasolite structure) and space group I2/a or Ia. The intermediate β phase exists only in very narrow temperature interval between T₁ and T₂. The γ polymorph is stable in the T₂<T<T₃ temperature range and has an orthorhombic unit cell with a=36.1229(6)Å, b=17.1114(3)Å, c=12.0502(3)Å (a=3a_c−3c_c, b=2b_c, c=a_c+c_c) at 250 °C and space group Fddd. Above T₃ the cubic δ polymorph forms with a_c=8.5786(4)Å at 400 °C and space group . The similarity between the K₃AlF₆ and K₃MoO₃F₃ compounds is discussed.     

Metal phosphonates containing pyridyl N-oxide groups: Syntheses of Cd{(2-C5H4NO)CH(OH)PO3}(H2O)2 and Zn{(4-C5H4NO)CH(OH)PO3} with chain and layer structures

This paper reports the syntheses and characterization of two phosphonate compounds Cd{(2-C₅H₄NO)CH(OH)PO₃}(H₂O)₂ (1) and Zn{(4-C₅H₄NO)CH(OH)PO₃} (2) based on hydroxy(2-pyridyl N-oxide)methylphosphonic and hydroxy(4-pyridyl N-oxide)methylphosphonic acids. Compound 1 has a chain structure in which dimers of edge-shared {CdO₆} octahedra are linked by {CPO₃} tetrahedra through corner-sharing. The pyridyl rings reside on the two sides of the inorganic chain. Compound 2 has a layer structure where the inorganic chains made up of corner-sharing {ZnO₄} and {CPO₃} tetrahedra are covalently connected by pyridyl N-oxide groups. Crystal data for 1: triclinic, space group , a=6.834(1) Å, b=7.539(1) Å, c=10.595(2) Å, α=84.628(3)°, β=74.975(4)°, γ=69.953(4)°. For 2: triclinic, space group , a=5.219(1) Å, b=8.808(2) Å, c=9.270(2) Å, α=105.618(5)°, β=95.179(4)°, γ=94.699(4)°.     

Supramolecular assembly of organic bicapped Keggin polyoxometalate

Two novel supramolecular assemblies of organic bicapped Keggin polyoxometalates (pbpy)₈H₃[PW₁₂O₄₀]·2H₂O (1) and (pbpy)₄H[PMo₁₂O₄₀(VO)] (2) (pbpy=5-phenyl-2-(4-pyridinyl)pyridine) have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Crystallographic data for compound (1), C₁₂₈H₁₀₃N₁₆O₄₂PW₁₂, triclinic, space group : a=13.4759(8) Å, b=14.6395(11) Å, c=16.5743(10) Å, α=95.764(2)°, β=102.166(2)°, γ=92.9870(10)°, Z=1, V=3171.1(4) Å³; for compound (2), C₆₄H₄₉N₈O₄₁PMo₁₂V, triclinic, space group : a=11.5377(11) Å, b=12.7552(8) Å, c=14.9599(10) Å, α=72.270(4)°, β=88.916(2)°, γ=67.865(4)°, Z=1, V=1931.0(3) Å³. X-ray analyses show that both 1 and 2 represent rare organic bicapped Keggin structures and are supported by supramolecular interactions to extend into a 3D framework. In particular, the unusual structure feature of compound 2 contains a simultaneously organic and inorganic capped structure.     

New open-framework three-dimensional lanthanide oxalates containing as a template the diprotonated 1,2- or 1,3-diaminopropane

Single crystals of three new open-framework lanthanide oxalates have been synthesized hydrothermally, in the presence of 1,2-diaminopropane, (C₃N₂H₁₂)[Nd(H₂O)(C₂O₄)₂]₂·3H₂O I and (C₃N₂H₁₂)[Yb(C₂O₄)₂]₂·5H₂O II, or 1,3-diaminopropane (C₃N₂H₁₂)₂[La₂(C₂O₄)₅]·5H₂O III. Their structures have been determined by X-ray diffraction data: I and III crystallize in the triclinic system, space group P-1, with , , , α=93.092(5)°, β=93.930(6)°, γ=108.359(5)° and , , , α=104.585(4)°, β=108.268(5)°, γ=111.132(5)°, respectively while II crystallizes in the orthorhombic system, space group F2dd, with , , . The three-dimensional (3D) framework of these compounds is built up by the linkages of lanthanide atoms and the oxygen atoms of the bischelating oxalate ligands. Instead of four chelating oxalate units surrounding a lanthanide atom (I and II), both lanthanum atoms, in III, are surrounded by five chelating oxalate groups and that is new. In all the cases within the frame, are observed 8- and 12-membered channels where are localized the guest species, 1,2- or 1,3-diaminopropane cations and free water molecules. The ratio of the guest number (especially the diaminopropane) per 12-membered ring could tune the shape and the size of 12-membered channels: thus, the 12-membered channels, observed for I and II, have elliptical cross-section (5.5 Å×11.4 Å and 5.2 Å×9.5 Å) while those, observed for III, have nearly circular cross-section (9.1 Å×9.5 Å). The lanthanide atoms are 8, 9 and 10-fold coordinated for Yb (II), Nd (I) and La (III), respectively.     

Synthesis and crystal structure of new uranyl tungstates M2(UO2)(W2O8) (M=Na, K), M2(UO2)2(WO5)O (M=K, Rb), and Na10(UO2)8(W5O20)O8

The solid-state reactions of UO₃ and WO₃ with M₂CO₃ (M=Na, K, Rb) at 650°C for 5 days result, accordingly the starting stoichiometry, in the formation of M₂(UO₂)(W₂O₈) (M=Na (1), K (2)), M₂(UO₂)₂(WO₅)O (M=K (3), Rb (4)), and Na₁₀(UO₂)₈(W₅O₂₀)O₈ (5). The crystal structures of compounds 2, 3, 4, and 5 have been determined by single-crystal X-ray diffraction using Mo(Kα) radiation and a charge-coupled device detector. The crystal structures were solved by direct methods and Fourier difference techniques, and refined by a least-squares method on the basis of F² for all unique reflections. For (1), unit-cell parameters were determined from powder X-ray diffraction data. Crystallographic data: 1, monoclinic, a=12.736(4) Å, b=7.531(3) Å, c=8.493(3) Å, β=93.96(2)°, ρ_cal=6.62(2) g/cm³, ρ_mes=6.64(1) g/cm³, Z=4; 2, orthorhombic, space group Pmcn, a=7.5884(16) Å, b=8.6157(18) Å, c=13.946(3) Å, ρ_cal=6.15(2) g/cm³, ρ_mes=6.22(1) g/cm³, Z=8, R1=0.029 for 80 parameters with 1069 independent reflections; 3, monoclinic, space group P2₁/n, a=8.083(4) Å, b=28.724(5) Å, c=9.012(4) Å, β=102.14(1)°, ρ_cal=5.83(2) g/cm³, ρ_mes=5.90(2) g/cm³, Z=8, R1=0.037 for 171 parameters with 1471 reflections; 4, monoclinic, space group P2₁/n, a=8.234(1) Å, b=28.740(3) Å, c=9.378(1) Å, β=104.59(1)°, ρ_cal=6.13(2) g/cm³,  g/cm³, Z=8, R1=0.037 for 171 parameters with 1452 reflections; 5, monoclinic, space group C2/c, a=24.359(5) Å, b=23.506(5) Å, c=6.8068(14) Å, β=94.85(3)°, ρ_cal=6.42(2) g/cm³,  g/cm³, Z=8, R1=0.036 for 306 parameters with 5190 independent reflections. The crystal structure of 2 contains linear one-dimensional chains formed from edge-sharing UO₇ pentagonal bipyramids connected by two octahedra wide (W₂O₈) ribbons formed from two edge-sharing WO₆ octahedra connected together by corners. This arrangement leads to [UW₂O₁₀]²⁻ corrugated layers parallel to (001). Owing to the unit-cell parameters, compound 1 probably contains similar sheets parallel to (100). Compounds 3 and 4 are isostructural and the structure consists of bi-dimensional networks built from the edge- and corner-sharing UO₇ pentagonal bipyramids. This arrangement creates square sites occupied by W atoms, a fifth oxygen atom completes the coordination of W atoms to form WO₅ distorted square pyramids. The interspaces between the resulting [U₂WO₁₀]²⁻ layers parallel to plane are occupied by K or Rb atoms. The crystal structure of compound 5 is particularly original. It is based upon layers formed from UO₇ pentagonal bipyramids and two edge-shared octahedra units, W₂O₁₀, by the sharing of edges and corners. Two successive layers stacked along the [100] direction are pillared by WO₄ tetrahedra resulting in sheets of double layers. The sheets are separated by Na⁺ ions. The other Na⁺ ions occupy the rectangular tunnels created within the sheets. In fact complex anions W₅O₂₀¹⁰⁻ are built by the sharing of the four corners of a WO₄ tetrahedron with two W₂O₁₀ dimmers, so, the formula of compound 5 can be written Na₁₀(UO₂)₈(W₅O₂₀)O₈.     

Topologically novel copper molybdate phases based on 3,4′-dipyridylketone: Hydrothermal synthesis, structural characterization, and magnetic properties

Hydrothermal treatment of CuCl₂·2H₂O, MoO₃, and 3,4′-dipyridylketone (3,4′-dpk) in 1:1:2 mole ratio afforded the new mixed metal oxide phases [Cu₂(MoO₄)₂(3,4′-dpk)(H₂O)] (1) or [Cu₄(3,4′-dpk)₄(Mo₈O₂₆)] (2), depending on the pH of the initial reaction mixture. Compound 1 possesses unique one-dimensional (1-D) [Cu₂(MoO₄)₂(H₂O)]_n ribbons constructed from the linkage of {Cu^II₄O₆} tetrameric units through isolated [MoO₄]^2- tetrahedra. These ribbons in turn are connected into a two-dimensional (2-D) coordination polymer structure by tethering 3,4′-dpk ligands. Compound 2, containing monovalent copper ions, manifests an unprecedented “X-rail” 1-D extended structure with (6²8)₄(6⁶) topology formed from the bracketing of discrete [β-Mo₈O₂₆]^4- anions by four chains. The variable temperature magnetic susceptibility behavior of 1 was fit to a linear tetramer model, with g=2.03(3), J₁=25.8(7) cm^-1 and J₂=−46(1) cm^-1. Antiferromagnetic inter-tetramer interactions (zJ′=−0.21(3) cm^-1) were also evident. Crystallographic data: 1 monoclinic, P2₁/c, a=10.3911(11) Å, b=6.9502(6) Å, c=22.958(2) Å, β=100.658(7)°, V=1629.5(3) Å³, R₁=0.1256, and wR₂=0.2038; 2 triclinic, a=10.9000(3) Å, b=11.7912(4) Å, c=13.5584(4) Å, α=102.482(2)°, β=102.482(2)°, γ=117.481(2)°, V=1450.98(8) Å³, R₁=0.0428, and wR₂=0.0630.     

Channels occupancy and distortion in new lithium uranyl phosphates with three-dimensional open-frameworks

Three new lithium uranyl phosphates, Li₂(UO₂)₃(PO₄)₂O (1), Li(UO₂)₄(PO₄)₃ (2) and Li₃(UO₂)₇(PO₄)₅O (3) were synthesized and studied. Powders of 1 and 2 were synthesized via solid state reaction, and single crystals of the three compounds were obtained by melting of 1 and 2 powders. The structures of the three compounds have been solved and refined from single crystal X-ray diffraction data. In the three compounds, the uranium atoms occupy square and pentagonal bipyramids. The uranium square bipyramids and phosphate tetrahedra are connected by vertices to form two types of layers with autunite sheet anion-topology and denoted S and D, respectively. The uranyl pentagonal bipyramids share opposite equatorial edges to form infinite chains. Mutually perpendicular chains are hung on each side of the sheets to build frameworks with non-crossing perpendicular channels that accommodate the lithium ions. Various stacking sequences of the S and D layers, S-S, D-D and S-D, generate three different frameworks in 1, 2 and 3, respectively. These compounds are similar to the recently reported vanadate analogous. However, the phosphate tetrahedra, smaller than the vanadate ones, gives distortion of the layers and a lowering of the symmetry and/or a change of periodicity. The electrical conductivity of 1 and 2 was measured using impedance spectroscopy method. The rather low conductivity of the lithium cations is explained by the crystal structure and the Li⁺ position within the tunnels. These results corroborate those on the analogous three-dimensional alkaline uranyl vanadates. Crystallographic data: 293 K, BRUKER X8-APEX2 X-ray diffractometer, 4 K CCD detector, MoKα, λ=0.71073 Å, full-matrix least-squares refinement on the basis of F. 1, Tetragonal symmetry, space group I4₁/amd, Z=4 with a=7.1109(2) Å and c=25.0407(8) Å, R=0.034 and wR=0.047 for 38 parameters with 479 independent reflections with I?3σ(I). 2, monoclinic symmetry, space group P2₁/c, Z=4 and a=9.8829(2) Å, b=9.8909(2) Å, c=17.4871(4) Å and β=106.198(1)°, R=0.021 and wR=0.031 for 249 parameters with 4201 independent reflections with I?3σ(I). 3, Tetragonal symmetry, space group with a=9.9305(2) Å and c=14.5741(3) Å, R=0.035 and wR=0.038 for 137 parameters with 4527 independent reflections with i?3σ(I).     

The structural phase transitions of aminoguanidinium(1+) dihydrogen phosphate—study of crystal structures, vibrational spectra and thermal behavior

Aminoguanidinium(1+) dihydrogen phosphate was prepared by crystallization from aqueous solution. On the basis of the results of DSC measurements, X-ray structural analysis was carried out at temperatures of 160, 215 and 293 K for three aminoguanidinium(1+) dihydrogen phosphate phases ( |Z=2|non-ferroic |melting point 408 K; II |201-222 K|(2) |Z=2|non-ferroic|-; III |<201 K|(2)|Z=4|non-ferroic|-). The triclinic unit cell dimensions (a=6.8220(2), b=7.1000(2), c=7.4500(2) Å, α=86.925(2)°, β=80.731(2)°, γ=79.630(2)°, V=350.21(2) Å³—phase I) are similar for all three structural phases with the exception of phase III, where doubling of the c-axis length leads to an increase in the volume to 692.34(3) Å³. The crystal structure of all three modifications consists of parallel layers of dihydrogen phosphate anions that are interconnected by aminoguanidinium(1+) cations through hydrogen bonds of the N-H…O type. The planar aminoguanidinium(1+) cations are oriented almost parallel to each other and are perpendicular to the anion layers. The primary differences amongst phases I, II and III lie in the location of the H atom in the short O-H…O bonds connecting the dihydrogen phosphate anions in layers. The FTIR and FT Raman spectra of natural and deuterated compounds were recorded and interpreted. The FTIR spectra were studied down to a temperature of 90 K.     

Reactivity of cyclopalladated compounds derived from biphenyl-2-ylamine towards carbon monoxide, butyl isocyanide and alkynes

The reactivity of the dimeric cyclopalladated compounds derived from biphenyl-2-ylamine (μ-X)₂[κ²-N2′,C1-1-Pd-2-{(2′-NH₂C₆H₄)C₆H₄}]₂ [X = OAc (1), X = Cl (2)] towards unsaturated organic molecules is reported. Compound 1 reacted with carbon monoxide and ^tbutyl isocyanide producing phenanthridin-6(5H)-one and N-tert-butylphenanthridin-6-amine in 63% and 88% yield, respectively. Compound 2 reacted separately with diphenylacetylene and 3-hexyne, affording the mononuclear organopalladium compounds [κ²-N2″,C1-η²-C2,C3- 1-Pd{(R-CC-R)₂-2′-(2″-NH₂C₆H₄)C₆H₄}Cl] [R = Ph (5), R = Et (6)] in 50-60% yield, which derived from the insertion of two alkyne molecules into the C-Pd σ bonds of 2. The crystal structure of compounds 5 and 6 has been determined. Compound 5 crystallized in the monoclinic space group P2₁/n with a = 13.3290(10) Å, b = 10.6610(10) Å and c = 22.3930(10) Å and β = 100.2690(10)°. Compound 6 crystallized in the triclinic space group with a = 7.271(7) Å, b = 10.038(3) Å and c = 16.012(5) Å, and α = 106.79(3)°, β = 96.25(4)° and γ = 99.62(4)°. The crystal structures of 5 and 6 have short intermolecular Pd-Cl?H-N-Pd non-conventional hydrogen bonds, which associated the molecules in chains in the first case and in dimers in the second.     

Hydrothermal synthesis and crystal structure of a three-dimensional metal selenite containing double helical chains: Fe3(H2O)(SeO3)3

A novel three-dimensional (3D) transition metal selenite Fe₃(H₂O)(SeO₃)₃ (1) has been hydrothermally synthesized and characterized by the elemental analyses, IR spectrum, TG analysis and the single-crystal X-ray diffraction. Compound 1 crystallizes in the triclinic system, space group , with a=8.0916(16) Å, b=8.2089(16) Å, c=8.5679(17) Å, α=69.21(3)°, β=62.74(3)°, γ=67.16(3)°, Z=2, and R₁[I>2σ(I)]=0.0379. Compound 1 exhibits an interesting 3D framework formed by {FeO₆} octahedra and {SeO₃} trigonal pyramids via the corner- and/or edge-sharing mode. Furthermore, compound 1 consists of left-handed and right-handed helical chains, which are further entangled to form the double helical chains.     

Synthesis and characterization of organic-inorganic hybrid compounds with a pillared layer structure: Ga2(4,4′-bpy)(XO4)2 (X=P, As)

Two organic-inorganic hybrid compounds, Ga₂(4,4′-bpy)(PO₄)₂, 1, and Ga₂(4,4′-bpy)(AsO₄)₂, 2, have been synthesized under hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction. The two compounds are isostructural and crystallize in the triclinic space group (No. 2) with a=4.9723(9) Å, b=5.770(1) Å, c=11.812(2) Å, α=78.268(3)°, β=89.159(3)° γ=88.344(3)°, V=331.7(2) Å³, Z=1, and R1=0.0377 for 1, and a=5.1111(7) Å, b=5.9327(8) Å, c=11.788(2) Å, α=79.497(2)°, β=88.870(2)°, γ=88.784(2)°, V=351.3(2) Å³, and R1=0.0264 for 2. The structure consists of neutral sheets of GaXO₄ (X=P or As) which are pillared through 4,4′-bipyridine ligands. Each oxide layer, which is formed only by four-membered rings, is constructed from corner-sharing GaO₄N trigonal bipyramids and XO₄ tetrahedra. The title compounds are two of the few examples in which the gallium atoms are exclusively five-coordinate.     

Reactions of pyridyl donors with halogens and interhalogens: an X-ray diffraction and FT-Raman investigation

Three different N-donors L, namely N-ethyl-N′-3-pyridyl-imidazolidine-4,5-dione-2-thione (1), N,N′-bis(3-pyridylmethyl)-imidazolidine-4,5-dione-2-thione (2), and tetra-2-pyridyl-pyrazine (3), bearing one, two and four pyridyl substituents, respectively, have been reacted with halogens X₂ (X = Br, I) or interhalogens XY (X = I; Y = Cl, Br). CT σ-adducts L · nXY, bearing linear N?XY moieties (L = 3; X = I; Y = Br, I; n = 2), and salts containing the protonated cationic donors H_nLⁿ⁺ (L = 1 − 3; n = 1, 2, 4), counterbalanced by Cl⁻, Br⁻, , , , , I₂Br⁻, , or anions, have been isolated. Among the reactions products, (H1⁺)Cl⁻, (H1⁺)Br⁻, , , and 3 · 2IBr have been characterised by single-crystal X-ray diffraction. The nature of the products has been elucidated based on elemental analysis and FT-Raman spectroscopy supported by MP2 and DFT calculations.     

The A1−xUNbO6−x/2 compounds (x=0, A=Li, Na, K, Cs and x=0.5, A=Rb, Cs): from layered to tunneled structure

Attempts to prepare alkaline metal uranyl niobates of composition A_1−xUNbO_6−x/2 by high-temperature solid-state reactions of A₂CO₃, U₃O₈ and Nb₂O₅ led to pure compounds for x=0 and A=Li (1), Na (2), K (3), Cs (4) and for x=0.5 and A=Rb (5), Cs (6). Single crystals were grown for 1, 3, 4, 5, 6 and for the mixed Na_0.92Cs_0.08UNbO₆ (7) compound. Crystallographic data: 1, monoclinic, P2₁/c, a=10.3091(11), b=6.4414(10), c=7.5602(5) Å, β=100.65(1), Z=4, R₁=0.054 (wR₂=0.107); 3, 5 and 7 orthorhombic, Pnma, Z=8, with a=10.307(2), 10.272(4) and 10.432(3) Å, b=7.588(1), 7.628(3) and 7.681(2) Å, c=13.403(2), 13.451(5) and 13.853(4) Å, R₁=0.023, 0.046 and 0.036 (wR₂=0.058, 0.0106 and 0.088) for 3, 5 and 7, respectively; 6, orthorhombic, Cmcm, Z=8, and a=13.952(3), b=10.607(2) Å, c=7.748(2) Å, R₁=0.044 (wR₂=0.117).The crystal structure of 1 is characterized by layers of uranophane sheet anion topology parallel to the (100) plane. These layers are formed by the association by edge-sharing of chains of edge-shared UO₇ pentagonal bipyramids and chains of corner-shared NbO₅ square pyramids alternating along the [010] direction. The Li⁺ ions are located between two consecutive layers and hold them together; the Li⁺ ions and two layers constitute a neutral “sandwich” {(UNbO₆)⁻-(Li)₂²⁺-(UNbO₆)⁻}. In this unusual structure, the neutral sandwiches are stacked one above another with no formal chemical bonds between the neutral sandwiches.The homeotypic compounds 3, 5, 6, 7 have open-framework structures built from the association by edge-sharing in two directions of parallel chains of edge-shared UO₇ pentagonal bipyramids and ribbons of two edge-shared NbO₆ octahedra further linked by corners. In 3, 5 and 7, the mono-dimensional large tunnels created in the [001] direction by this arrangement can be considered as the association by rectangular faces of two columns of triangular face-shared trigonal prisms of uranyl oxygens. In 3 and 7, all the trigonal prisms are occupied by the alkaline metal, in 5, they are half-occupied. In 6, the polyhedral arrangement is more symmetric and the tunnels created in the [010] direction are built of face-sharing cubes of uranyl oxygens totally occupied by the Cs atoms. This last compound well illustrates the structure-directing effect of the conterion.     

Crystal chemistry and ion-exchange properties of the layered uranyl iodate K[UO2(IO3)3]

Single crystals of the potassium uranyl iodate, K[UO₂(IO₃)₃] (1), have been grown under mild hydrothermal conditions. The structure of 1 contains two-dimensional sheets extending in the [ab] plane that consist of approximately linear UO₂²⁺ cations bound by iodate anions to yield UO₇ pentagonal bipyramids. There are three crystallographically unique iodate anions, two of which bridge between uranyl cations to create sheets, and one that is monodentate and protrudes in between the layers in cavities. K⁺ cations form long ionic contacts with oxygen atoms from the layers forming an eight-coordinate distorted dodecahedral geometry. These cations join the sheets together. Ion-exchange reactions have been carried out that indicate the selective uptake of Cs⁺ over Na⁺ or K⁺ by 1. Crystallographic data (193 K, MoKα, ): 1, orthorhombic, Pbca, a=11.495(1) Å, b=7.2293(7) Å, c=25.394(2) Å, Z=8, R(F)=1.95% for 146 parameters with 2619 reflections with I>2σ(I).     

The effect of titanium alkoxides in the synthesis of heterobimetallic complexes by titanocene(III) alkoxide-induced metal-metal bond cleavage of metal carbonyl dimers

A series of titanocene(III) alkoxides L₂Ti(III)OR where L = Cp, R = Et(1b), ^tBu(1a), 2,6-Me₂C₆H₃(1c), 2,6-^tBu₂-4-Me-C₆H₂(1d), or L = Cp*, R = Me(2e), ^tBu(2a), Ph(2f) was synthesized and subjected to reaction with [CpM(CO)₃]₂ [M = Mo, W], [CpRu(CO)₂]₂, and Co₂(CO)₈. The Ti(III) precursors 1a, 1c, 2a, 2e, and 2f reacted with [CpM(CO)₃]₂ [M = Mo, W] to form heterobimetallic complexes L₂Ti(OR)(μ-OC)(CO)₂MCp [M = Mo, W], of which Ti and M are linked by an isocarbonyl bridge. Reactions of these Ti(III) complexes with Co₂(CO)₈ resulted in formation of Ti-Co₁ heterobimetallic complexes, from 2a, 2e, or 2f, or Ti-Co₃ tetrametallic complexes, Cp₂Ti(O^tBu)(μ-OC)Co₃(CO)₉ from 1a, 1b, or 1c. The products were characterized by NMR, IR, and X-ray crystallography. Reaction mechanisms were proposed from these results, in particular, from steric/electronic effects of titanium alkoxides.     

Synthesis and characterization of aluminum complexes of 2-pyrazol-1-yl-ethenolate ligands

The synthesis and the characterization of some new aluminum complexes with bidentate 2-pyrazol-1-yl-ethenolate ligands are described. 2-(3,5-Disubstituted pyrazol-1-yl)-1-phenylethanones, 1-PhC(O)CH₂-3,5-R₂C₃HN₂ (1a, R = Me; 1b, R = Bu^t), were prepared by solventless reaction of 3,5-dimethyl pyrazole or 3,5-di-tert-butyl pyrazole with PhC(O)CH₂Br. Reaction of 1a or 1b with (R¹ = Me, Et) yielded N,O-chelate alkylaluminum complexes (2a, R = R¹ = Me; 2b, R = Bu^t, R¹ = Me; 2c, R = Me, R¹ = Et). Compound 1a was readily lithiated with LiBuⁿ in thf or toluene to give lithiated species 3. Treatment of 3 with 0.5 equiv of MeAlCl₂ or AlCl₃ yielded five-coordinated aluminum complexes [XAl(OC(Ph)CH{(3,5-Me₂C₃HN₂)-1})₂] (4, X = Me; 5, X = Cl). Reaction of 5 with an equiv of LiHBEt₃ generated [Al(OC(Ph)CH{(3,5-Me₂C₃HN₂)-1})₃] (6). Complex 6 was also obtained by reaction of 3 with 1/3 equiv of AlCl₃. Treatment of 5 with 2 equiv of AlMe₃ yielded complex 2a, whereas with an equiv of AlMe₃ afforded a mixture of 2a and [Me(Cl)AlOC(Ph)CH{(3,5-Me₂C₃HN₂)-1}] (7). Compounds 1a, 1b, 2a-2c and 4-6 were characterized by elemental analyses, NMR and IR (for 1a and 1b) spectroscopy. The structures of complexes 2a and 5 were determined by single crystal X-ray diffraction techniques. Both 2a and 5 are monomeric in the solid state. The coordination geometries of the aluminum atoms are a distorted tetrahedron for 2a or a distorted trigonal bipyramid for 5.