Synthesis, characterization, and ethylene polymerization behavior of [(RR′-admpzp)2Ti(OPr)2] complexes (RR′-admpzp = 1-dialkylamino-3-(3,5-dimethyl-pyrazol-1-yl)-propan-2-olate)

[(RR′-admpzp)₂Ti(OPrⁱ)₂] complexes (2a-c), synthesized from reaction of Ti(OPrⁱ)₃Cl (0.5 equiv) with 1-dialkylamino-3-(3,5-dimethyl-pyrazol-1-yl)-propan-2-ol compounds in the presence of triethylamine (0.5 equiv), are pseudo-octahedral with each RR′-admpzp ligand κ²-O,N(pyrazolyl) coordinated to the titanium center. In solution, 2a-c adopt isomeric structures that are in dynamic equilibrium. At 23 °C, 2a-c/1000 MAO catalyst systems furnished high molecular weight polymers with narrow molecular weight distributions (M_w/M_n = 2.7-2.8). At 100 °C, 2a-c/MAO catalyst systems exhibited increased polymerization activity and 2c/1000 MAO system furnished high molecular weight polyethylene with a molecular weight distribution (M_w/M_n = 2.1) that is close to that found for single-site catalysts.     

A new catalytic system for the copolymerization of dicyclopentadiene with CO: PdCl2/phen/M(CF3SO3)n

A new three-component catalytic system, PdCl₂/phen/M(CF₃SO₃)_n, was studied in the copolymerization of dicyclopentadiene (DCPD) with CO. It was found that the PdCl₂/phen/CF₃SO₃H catalytic system gave a very low catalytic activity, and the PdCl₂/phen/M(CF₃SO₃)_n catalytic system exhibited high activity when M(CF₃SO₃)_n was introduced instead of CF₃SO₃H. The resultant cooligomer was analyzed using various techniques such as FT-IR, ¹H NMR, ¹³C NMR, DSC and TGA. The results indicated that the copolymer was a polyspiroketal (PS) of CO and DCPD. Due to the tension of the ring of DCPD, the degree of copolymerization is low and the degree of crystallinity is also not high. The effects of ligands, M(CF₃SO₃)_n, solvents, 1,4-benzoquinone/PdCl₂ molar ratio, and temperatures on the copolymerization have been discussed in detail. The results showed that this novel catalytic system exhibited highly efficient activity, especially when 1,10-phenanthroline (phen) was used as ligand and Cu(CF₃SO₃)₂ was used as cocatalyst. The corresponding reaction rate was 49 000 g PS/molPd h when the reaction was carried out at 60 °C and 3.0 MPa of CO. The weight average molecular weight (M_w) and the number average molecular weight (M_n) of the resultant cooligomer were 1180 g/mol and 564 g/mol, respectively.     

Effect of methylaluminoxane/transition-metal ratio on the physical properties and chemical composition distributions of ethylene-hexene copolymers produced by a rac-Et(Ind)2ZrCl2/TiCl4/MAO/SMB catalyst

A silica-magnesium bisupport (SMB) was prepared by a sol-gel method for use as a support for the impregnation of TiCl₄ and rac-Et(Ind)₂ZrCl₂. The prepared rac-Et(Ind)₂ZrCl₂/TiCl₄/MAO(methylaluminoxane)/SMB catalyst was applied to the ethylene-hexene copolymerization under the conditions of variable Al(MAO)/Zr ratio and fixed Al(TEA, triethylaluminum)/Ti ratio. The effect of Al(MAO)/Zr ratio on the physical properties and chemical composition distributions of ethylene-hexene copolymers produced by a rac-Et(Ind)₂ZrCl₂/TiCl₄/MAO/SMB catalyst was investigated. The catalytic activity of rac-Et(Ind)₂ZrCl₂/TiCl₄/MAO/SMB was steadily increased with increasing Al(MAO)/Zr ratio from 200 to 500. The ethylene-hexene copolymer produced with Al(MAO)/Zr = 300, 400, and 500 showed two melting points at around 110 °C and 130 °C, while that produced with Al(MAO)/Zr = 200 showed one melting point at 136 °C. The number of chemical composition distribution (CCD) peaks was increased from 4 to 7 and the short chain branches of ethylene-hexene copolymer were distributed over lower temperature region with increasing Al(MAO)/Zr ratio. The lamellas in the copolymer were distributed over lower temperature region and the small lamellas in the copolymer were increased with increasing Al(MAO)/Zr ratio. The rac-Et(Ind)₂ZrCl₂/TiCl₄/MAO/SMB catalyst preferably produced a ethylene-hexene copolymer with non-blocky sequence ([EHE]) with increasing Al(MAO)/Zr ratio.     

Controlled/living cationic polymerization of styrene with BF3OEt2 as a coinitiator in the presence of water: Improvements and limitations

The controlled/living cationic polymerization of styrene using R-OH/BF₃OEt₂ (R-OH = 1-phenylethanol (1), 2-phenyl-2-propanol (2) and 1-(4-methoxyphenyl)ethanol (3)) at 0 °C in CH₂Cl₂ and in the presence of water was investigated. With 1/BF₃OEt₂, the poor control over molecular weight and molecular weight distribution was ascribed to a competitive protonic initiation induced by water. The molecular weight of the polymers obtained with 2/BF₃OEt₂ and 3/BF₃OEt₂ at low water content ([H₂O] ? 0.11 M) increased in direct proportion to the monomer conversion in agreement with the calculated values, assuming that one initiator molecule generates one polymer chain, but the molecular weight distribution was found relatively broad (M_w/M_n ∼ 1.8). ¹H NMR analyses confirmed that polymerization proceeds via reversible activation of C-OH terminus, but some loss of hydroxyl functionality was revealed. Some trials using high water contents in the recipe ([H₂O] ? 1.6 M) produced only traces of polymer due to catalyst decomposition.     

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.     

Synthesis, crystal structure and electrical characterization of two new potassium uranyl molybdates K2(UO2)2(MoO4)O2 and K8(UO2)8(MoO5)3O6

Two new potassium uranyl molybdates K₂(UO₂)₂(MoO₄)O₂ and K₈(UO₂)₈(MoO₅)₃O₆ have been obtained by solid state chemistry . The crystal structures were determined by single crystal X-ray diffraction data, collected with MoKα radiation and a charge coupled device (CCD) detector. Their structures were solved using direct methods and Fourier difference techniques and refined by a least square method on the basis of F² for all unique reflections, with R₁=0.046 for 136 parameters and 1412 reflections with I?2σ(I) for K₂(UO₂)₂(MoO₄)O₂ and R₁=0.055 for 257 parameters and 2585 reflections with I?2σ(I) for K₈(UO₂)₈(MoO₅)₃O₆. The first compound crystallizes in the monoclinic symmetry, space group P2₁/c with a=8.250(1) Å, b=15.337(2) Å, c=8.351(1) Å, β=104.75(1)°, ρ_mes=5.22(2) g/cm³, ρ_cal=5.27(2) g/cm³ and Z=4. The second material adopts a tetragonal unit cell with a=b=23.488(3) Å, c=6.7857(11) Å, ρ_mes=5.44(3) g/cm³, ρ_cal=5.49(2) g/cm³, Z=4 and space group P4/n.In both structures, the uranium atoms adopt a UO₇ pentagonal bipyramid environment, molybdenum atoms are in a MoO₄ tetrahedral environment for K₂(UO₂)₂(MoO₄)O₂ and MoO₅ square pyramid coordination in K₈(UO₂)₈(MoO₅)₃O₆. These compounds are characterized by layered structures. The association of uranyl ions (UO₇) and molybdate oxoanions MoO₄ or MoO₅, give infinite layers [(UO₂)₂(MoO₄)O₂]²⁻ and [(UO₂)₈(MoO₅)₃O₆]⁸⁻ in K₂(UO₂)₂(MoO₄)O₂ and K₈(UO₂)₈(MoO₅)₃O₆, respectively. Conductivity properties of alkali metal within the interlayer spaces have been measured and show an Arrhenius type evolution.     

Synthesis and structural investigation of the compounds containing HF2 anions: Ca(HF2)2, Ba4F4(HF2)(PF6)3 and Pb2F2(HF2)(PF6)

Three new compounds Ca(HF₂)₂, Ba₄F₄(HF₂)(PF₆)₃ and Pb₂F₂(HF₂)(PF₆) were obtained in the system metal(II) fluoride and anhydrous HF (aHF) acidified with excessive PF₅. The obtained polymeric solids are slightly soluble in aHF and they crystallize out of their aHF solutions. Ca(HF₂)₂ was prepared by simply dissolving CaF₂ in a neutral aHF. It represents the second known compound with homoleptic HF environment of the central atom besides Ba(H₃F₄)₂. The compounds Ba₄F₄(HF₂)(PF₆)₃ and Pb₂F₂(HF₂)(PF₆) represent two additional examples of the formation of a polymeric zigzag ladder or ribbon composed of metal cation and fluoride anion (MF⁺)_n besides PbF(AsF₆), the first isolated compound with such zigzag ladder. The obtained new compounds were characterized by X-ray single crystal diffraction method and partly by Raman spectroscopy. Ba₄F₄(HF₂)(PF₆)₃ crystallizes in a triclinic space group P1¯ with a=4.5870(2) Å, b=8.8327(3) Å, c=11.2489(3) Å, α=67.758(9)°, β=84.722(12), γ=78.283(12)°, V=413.00(3) Å³ at 200 K, Z=1 and R=0.0588. Pb₂F₂(HF₂)(PF₆) at 200 K: space group P1¯, a=4.5722(19) Å, b=4.763(2) Å, c=8.818(4) Å, α=86.967(10)°, β=76.774(10)°, γ=83.230(12)°, V=185.55(14) ų, Z=1 and R=0.0937. Pb₂F₂(HF₂)(PF₆) at 293 K: space group P1¯, a=4.586(2) Å, b=4.781(3) Å, c=8.831(5) Å, α=87.106(13)°, β=76.830(13)°, γ=83.531(11)°, V=187.27(18) Å³, Z=1 and R=0.072. Ca(HF₂)₂ crystallizes in an orthorhombic Fddd space group with a=5.5709(6) Å, b=10.1111(9) Å, c=10.5945(10) Å, V=596.77(10) Å³ at 200 K, Z=8 and R=0.028.     

Effects of cocatalyst on structure distribution of propylene polymers catalyzed by rac-Me2Si(Ind)2ZrCl2/aluminoxane

Propylene polymerization and propylene/1-octene copolymerization were studied using rac-Me₂SiInd₂ZrCl₂(1)/MAO or rac-Me₂SiInd₂ZrCl₂/(MAO + TIBA) as catalyst (methyl aluminoxane, MAO; AliBu₃, TIBA). The structure distribution of the polymers was characterized by temperature gradient extraction fractionation or precipitation fractionation, as well as by DSC analysis of the thermal segregated samples. By comparing the structure distribution of polypropylene and propylene-1-octene copolymer synthesized by 1/MAO and 1/(MAO + TIBA), it is found that adding TIBA in the catalyst system increase the blockiness of the polymer chain, especially in the copolymerization system. It is assumed that, when iso-butyl is incorporated in the aluminoxane, ion pair of the active center and the aluminoxane counter ion may exist in different states that show different catalytic behaviors, resulting in the formation of polymers with block structure.     

Various silyl-substituted cyclopentadienyl titanium complexes [CpSi(CH3)2X]TiCl3 as catalysts for syndiotactic polystyrene

Three silyl-substituted titanium trichloride complexes [CpSi(CH₃)₂X]TiCl₃ [X=Cl(1), Me(2), PhOMe(3)] were tested as catalyst precursors for the syndiospecific polymerization of styrene. The catalytic activity increased in the order 1 > 2 > 3. The highest activity was 2.42 × 10⁷ g s-PS/mol Ti mol S h using complex 1/MAO catalytic system at molar ratio of Al/Ti=2000. The effects of variation on polymerization temperature and Al/Ti ratio on the polymerization of styrene were also studied.     

Carbon coated Na3V2(PO4)3 as novel electrode material for sodium ion batteries

A Na₃V₂(PO₄)₃ sample coated uniformly with a layer of 6 nm carbon has been successfully synthesized by a one-step solid state reaction. This material shows two flat voltage plateaus at 3.4 V vs. Na⁺/Na and 1.63 V vs. Na⁺/Na in a nonaqueous sodium cell. When the Na₃V₂(PO₄)₃/C sample is tested as a cathode in a voltage range of 2.7-3.8 V vs. Na⁺/Na, its initial charge and discharge capacities are 98.6 and 93 mAh/g. The capacity retention of 99% can be achieved after 10 cycles. The electrode shows good cycle performance and moderate rate performance. When it is tested as an anode in a voltage range of 1.0-3.0 V vs. Na⁺/Na, the initial reversible capacity is 66.3 mAh/g and the capacity of 59 mAh/g can be maintained after 50 cycles. These preliminary results indicate that Na₃V₂(PO₄)₃/C is a new promising material for sodium ion batteries.     

Two new octahedral/pyramidal frameworks containing both cation channels and lone-pair channels: syntheses and structures of Ba2MnMn2(SeO3)6 and PbFe2(SeO3)4

The hydrothermal syntheses, single crystal structures, and some properties of Ba₂Mn^IIMn₂^III(SeO₃)₆ and PbFe₂(SeO₃)₄ are reported. These related phases contain three-dimensional frameworks of vertex (FeO₆) and vertex/edge linked (MnO₆) octahedra and SeO₃ pyramids. In each case, the MO₆/SeO₃ framework encloses two types of 8 ring channels, one of which encapsulates the extra-framework cations and one of which provides space for the Se^IV lone pairs. Crystal data: Ba₂Mn₃(SeO₃)₆, M_r=1201.22, monoclinic, P2₁/c (No. 14), a=5.4717 (3) Å, b=9.0636 (4) Å, c=17.6586 (9) Å, β=94.519 (1)°, V=873.03 (8) Å³, Z=2, R(F)=0.031, wR(F²)=0.070; PbFe₂(SeO₃)₄, M_r=826.73, triclinic, (No. 2), a=5.2318 (5) Å, b=6.7925 (6) Å, c=7.6445 (7) Å, α=94.300 (2)°, β=90.613 (2)°, γ=95.224 (2)°, V=269.73 (4) Å³, Z=1, R(F)=0.051, wR(F²)=0.131.     

Synthesis and crystal structure of two new uranyl oxychloro-vanadate layered compounds: M7(UO2)8(VO4)2O8Cl with M=Rb, Cs

Two new alkali uranyl oxychloro vanadates M₇(UO₂)₈(VO₄)₂O₈Cl with M=Rb, Cs, have been synthesized by solid-state reactions and their structures determined from single-crystal X-ray diffraction data. They crystallize in the orthorhombic system with space groups Pmcn and Pmmn, respectively. The a and b unit cell parameters are almost identical in both compounds while the c parameter in the Rb compound is doubled: Rb—a=21.427(5) Å, b=11.814(3) Å, c=14.203(3) Å, V=3595.1(1) Å³, Z=4, ρ_mes=5.93(2) g/cm³, ρ_cal=5.82(1) g/cm³; Cs—a=21.458(3) Å, b=11.773(2) Å, c=7.495(1) Å, V=1893.6(5) Å³, Z=2, ρ_mes=6.09(2) g/cm³, ρ_cal=6.11(1) g/cm³. A full-matrix least-squares refinement yielded R₁=0.0221, wR₂=0.0562 for 2675 independent reflections and R₁=0.0386, wR₂=0.1042 for 2446 independent reflections, for the Rb and Cs compounds, respectively. Data were collected with Mo(Kα) radiation and a charge coupled device (CCD) detector of a Bruker diffractometer. Both structures are characterized by [(UO₂)₈(VO₄)₂O₈Cl]_n⁷ⁿ⁻ layers parallel to the (001) plane. The layers are built up from VO₄ tetrahedra, UO₇ and UO₆Cl pentagonal bipyramids, and UO₆ distorded octahedra. The UO₇ and UO₆Cl pentagonal bipyramids are associated by sharing opposite equatorial edges to form infinite chains (UO₅-UO₄Cl-UO₅)_n parallel to the a axis. These chains are linked together by VO₄ tetrahedra, UO₆ octahedra, UO₇ corner sharing and UO₆Cl, Cl sharing. Both structures differ simply by the symmetry of the layers. The unit cell contains one centrosymmetric layer in the Cs compound, whereas in the two-layer unit cell of the Rb compound, two non-centrosymmetric consecutive layers are related by an inversion center. The layers appear to be held together by the alkali ions. The mobility of the M⁺ ions within the interlayer space in M₇(UO₂)₈(VO₄)₂O₈Cl and carnotite analog compounds is compared.     

Titanium ketimide complexes as α-olefin homo- and copolymerisation catalysts. X-ray diffraction structures of [TiCp(NCBu2)Cl2] (Cp=Ind, Cp*)

The synthesis of [TiInd(NC^tBu₂)Cl₂] and the applications of [TiCp^′(NC^tBu₂)Cl₂] (Cp^′=Ind, Cp*, Cp) as ethylene and propylene homopolymerisation catalysts, as well as its behaviour as catalysts of ethylene and 10-undecen-1-ol copolymerisation are described. The optimisation of the catalytic reactions showed that all compounds are very active homopolymerisation catalysts, particularly [TiInd(NC^tBu₂)Cl₂] that gives 123.37 × 10⁶ g/(molTi [E] h) and 50.77 × 10⁶ g/(molTi [P] h) of linear polyethylene and atatic polypropylene, respectively. The less active homopolymerisation catalyst, [TiCp(NC^tBu₂)Cl₂], is the most effective ethylene/10-undecen-1-ol copolymerisation catalyst, leading to the highest degree of polar monomer incorporation. The polymers obtained were characterised by NMR and DSC. The molecular structures of [TiCp^′(NC^tBu₂)Cl₂] (Cp^′=Ind, Cp*) were determined by X-ray diffraction studies.     

A study on methanol steam reforming to CO2 and H2 over the La2CuO4 nanofiber catalyst

The La₂CuO₄ crystal nanofibers were prepared by using single-walled carbon nanotubes as templates under mild hydrothermal conditions. The steam reforming of methanol (SRM) to CO₂ and H₂ over such nanofiber catalysts was studied. At the low temperature of 150 °C and steam/methanol=1.3, methanol was completely (100%, 13.8 g/h g catalyst) converted to hydrogen and CO₂ without the generation of CO. Within the 60 h catalyst lifespan test, methanol conversion was maintained at 98.6% (13.6 g/h g catalyst) and with 100% CO₂ selectivity. In the meantime, for distinguishing the advantage of nanoscale catalyst, the La₂CuO₄ bulk powder was prepared and tested for the SRM reaction for comparison. Compared with the La₂CuO₄ nanofiber, the bulk powder La₂CuO₄ showed worse catalytic activity for the SRM reaction. The 100% conversion of methanol was achieved at the temperature of 400 °C, with the products being H₂ and CO₂ together with CO. The catalytic activity in terms of methanol conversion dropped to 88.7% (12.2 g/h g catalyst) in 60 h. The reduction temperature for nanofiber La₂CuO₄ was much lower than that for the La₂CuO₄ bulk powder. The nanofibers were of higher specific surface area (105.0 m²/g), metal copper area and copper dispersion. The in situ FTIR and EPR experiments were employed to study the catalysts and catalytic process. In the nanofiber catalyst, there were oxygen vacancies. H₂-reduction resulted in the generation of trapped electrons [e] on the vacancy sites. Over the nanofiber catalyst, the intermediate H₂CO/HCO was stable and was reformed to CO₂ and H₂ by steam rather than being decomposed directly to CO and H₂. Over the bulk counterpart, apart from the direct decomposition of H₂CO/HCO to CO and H₂, the intermediate H₂COO might go through two decomposition ways: H₂COO=CO+H₂O and H₂COO=CO₂+H₂.     

New one-dimensional uranyl and neptunyl iodates: crystal structures of K3[(UO2)2(IO3)6](IO3)·H2O and K[NpO2(IO3)3]·1.5H2O

The uranyl and neptunyl(VI) iodates, K₃[(UO₂)₂(IO₃)₆](IO₃)·H₂O (1) and K[NpO₂(IO₃)₃]·1.5H₂O (2), have been prepared and crystallized under mild hydrothermal conditions. The structures of 1 and 2 both contain one-dimensional _∞¹[AnO₂(IO₃)₃]¹⁻(An=U,Np) ribbons that consist of approximately linear actinyl(VI) cations bound by iodate anions to yield AnO₇ pentagonal bipyramids. The AnO₇ units are linked by bridging iodate anions to yield chains that are in turn coupled by additional iodate anions to yield ribbons. The edges of the ribbons are terminated by monodentate iodate anions. For 1 and 2, K⁺ cations and water molecules separate the ribbons from one another. In addition, isolated iodate anions are also found between _∞¹[UO₂(IO₃)₃]¹⁻ ribbons in 1. In order to aid in the assignment of oxidation states in neptunyl containing compounds, a bond-valence sum parameter of 2.018 Å for Np(VI) bound exclusively to oxygen has been developed with b=0.37 Å. Crystallographic data (193 K, MoKα, λ=0.71073): 1, triclinic, , a=7.0609(4) Å, b=14.5686(8)  Å, c=14.7047(8)  Å, α=119.547(1)°, β=95.256(1)°, γ=93.206(1)°, Z=2, R(F)=2.49% for 353 parameters with 6414 reflections with I>2σ(I); (203 K, MoKα, λ=0.71073): 2, monoclinic, P2₁/c, a=7.796(4)  Å, b=7.151(3)  Å, c=21.79(1)  Å, β=97.399(7)°, Z=4, R(F)=6.33% for 183 parameters with 2451 reflections with I>2σ(I).     

Synthesis, vibrational and NMR spectroscopic characterization of [N(CH3)4][IO2F2] and X-ray crystal structure of [N(CH3)4]2[IO2F2][HF2]

The salt, [N(CH₃)₄][IO₂F₂], was prepared from [N(CH₃)₄][IO₃] and 49% aqueous HF, and characterized by Raman, infrared, and ¹⁹F NMR spectroscopy. Crystals of [N(CH₃)₄]₂[IO₂F₂][HF₂] were obtained by reduction of [N(CH₃)₄][cis-IO₂F₄] in the presence of [N(CH₃)₄][F] in CH₃CN solvent and were characterized by Raman spectroscopy and single-crystal X-ray diffraction: C2/m, a = 14.6765(2) Å, b = 8.60490(10) Å, c = 13.9572(2) Å, β = 120.2040(10)°, V = 1523.35(3) Å³, Z = 4 and R = 0.0192 at 210 K. The crystal structure consists of two IO₂⁻F₂ anions that are symmetrically bridged by two H⁻F₂ anions, forming a [F₂O₂I(FHF)₂IO₂F₂]⁴⁻ dimer. The symmetric bridging coordination for the H⁻F₂ anion in this structure represents a new bonding modality for the bifluoride anion.     

Homoleptic [M(XeF2)6] cations of copper(II) and zinc(II)—Syntheses and crystal structures of [M(XeF2)6](SbF6)2 (M = Cu, Zn)

[Cu(XeF₂)₆](SbF₆)₂ crystallizes in the rhombohedral symmetry with a = 1003.6(2) pm, c = 2246.5(12) pm at 200 K and Z = 3, space group (No. 148). [Zn(XeF₂)₆](SbF₆)₂ is isostructural to [Cu(XeF₂)₆](SbF₆)₂ with a = 1007(2) pm and c = 2243(6) pm. The structures are characterized by isolated homoleptic [M(XeF₂)₆]²⁺ (M = Cu, Zn) cations and of [SbF₆]⁻ octahedra.Reactions of M(SbF₆)₂ (M = Cu, Zn) with XeF₂ in anhydrous hydrogen fluoride (aHF) and reactions of MF₂ with Xe₂F₃SbF₆ in aHF always yield a mixture of [M(XeF₂)₆](SbF₆)₂, Xe₂F₃SbF₆ and MF₂.     

The layered metal Ti2PTe2

Crystals of Ti₂PTe₂ have been synthesised by chemical vapour transport. Ti₂PTe₂ crystallises, isostructural to the mineral tetradymite (Bi₂STe₂), in the space group R3¯m with unit-cell parameters a=3.6387(2) Å and c=28.486(2) Å for the hexagonal setting. In the structure, layers of isolated phosphide and telluride anions form an ordered close sphere-packing with titanium cations filling two-thirds of the octahedral voids. From XANES fluorescence, the presence of Ti⁴⁺ is clearly established. In accordance with the ionic formula (Ti⁴⁺)₂(P³⁻)(Te²⁻)₂(e⁻) metallic conductivity (ρ=40 μΩ cm at 300 K) and nearly temperature-independent paramagnetism are found. The electronic band structure shows bands of titanium states crossing the Fermi level in directions corresponding to the ab-plane and a band gap along the c-axis.     

Trimetallic FePd2 and FePt2 4-ferrocenyl-NCN pincer complexes

Ferrocene-bridged NCN pincer complexes of structural type Fe(η⁵-C₅H₄-4-NCN-1-MX)₂ (X = I: 6, M = Pd; 7, M = Pt; X = Cl: 8, M = Pt; NCN = [4-C₆H₂(CH₂NMe₂)₂-2,6]⁻) are accessible by the subsequent reaction of Fe(η⁵-C₅H₄-4-NCNH)₂ (4) with ⁿBuLi and [PtCl₂(SEt₂)₂] (synthesis of 8) or treatment of Fe(η⁵-C₅H₄-4-NCN-1-I)₂ (5) with [Pd₂(dba)₃] (synthesis of 6) or [Pt(tol)₂(SEt₂)]₂ (synthesis of 7) (dba = dibenzylidene acetone, tol = 4-tolyl). In addition, the Sonogashira cross-coupling of Fe(η⁵-C₅H₄I)₂ (1) with HCC-4-NCNH (2) gives Fe(η⁵-C₅H₄-CC-4-NCNH)₂ (3). The reaction behavior of 3 towards ^tBuLi is reported as well.Cyclovoltammetric studies show that the ferrocene entity can be oxidized reversibly. The Fe(II)/Fe(III) potential decreases with increasing electron density at the NCN pincer units due to the presence of the M-halide moiety (M = Pd, Pt).The solid state structure of Fe(η⁵-C₅H₄-4-NCN-1-PdI)₂ (6) is presented. In 6 the Fe(η⁵-C₅H₄)₂ unit connects two NCN-PdI pincer entities with palladium in a square-planar environment. The cyclopentadienyl ligands show a staggered conformation. The C₆H₂ rings are tilted by 23.5(3)° towards the C₅H₄ entities and the C₆H₂ plane is almost coplanar with the coordination plane (10.3(3)°).     

Ferromagnetic exchange coupling in phosphonato-bridged dinuclear copper(II) compound with monoethyl (pyridyn-2-ylmethyl)phosphonate ligand (2-mpmpe): Cu2(2-mpmpe)2(H2O)2(NO3)2

The interaction of diethyl (pyridyn-2-ylmethyl)phosphonate (2-pmpe) with Cu(NO₃)₂ · 6H₂O leads to a partial hydrolysis of the starting ligand and formation of the compound of the formula Cu₂(2-mpmpe)₂(H₂O)₂(NO₃)₂, where 2-mpmpe = monoethyl (pyridyn-2-ylmethyl)phosphonate. The crystal and molecular structure of a copper(II) compound was determined by single X-ray diffraction method. Its structure consists of five-coordinated in distorted square planar geometry (CuNO₄ chromophore) copper(II) ions doubly bridged by OPO from phosphonate. The Cu?Cu distance is 4.69 Å. The crystal packing is determined by the interdinuclear hydrogen bond system, which leads to a three-dimensional (3D) H-bonds network. The compound was characterized by infrared, ligand field, EPR spectroscopy, and magnetic studies. The magnetic properties of the title compound investigated over the 1.8–300 K, revealed the occurrence of a weak ferromagnetic coupling through phosphonate bridge (J = 1.86 cm⁻¹) and interdimer superexchange coupling through H-bond network (zJ′ = −0.17 cm⁻¹). Spectroscopic and magnetic properties are presented in the light of crystal structure.