Crystal Structure and Formation of TlPd3 and its new Hydride TlPd3H

TlPd₃ was synthesised from the elements in evacuated silica tubes at 600 °C. Alternatively, TlPd₃ was yielded by reduction of TlPd₃O₄ in N₂ gas atmosphere. Reduction of the oxide in H₂ gas atmosphere resulted in the formation of the new hydride TlPd₃H. The structure of tetragonal TlPd₃ (ZrAl₃ type, space group I4/mmm, a = 410.659(9) pm, c = 1530.28(4) pm) was reinvestigated by X‐ray and also by neutron powder diffraction as well as the structure of its previously unknown hydride TlPd₃H (cubic anti‐perovskite type structure, space group Pm\bar{3} m, a = 406.313(1) pm). In situ DSC measurements of TlPd₃ in hydrogen gas atmosphere showed a broad exothermic signal over a wide temperature range with two maxima at 280 °C and at 370 °C, which resulted in the product TlPd₃H. A dependency of lattice parameters of the intermetallic phase on reaction conditions is observed and discussed. Results of hydrogenation experiments at room temperature with gas pressures up to 280 bar hydrogen and at elevated temperatures with very low hydrogen gas pressures (1–2 bar) as well as results of dehydrogenation of the hydrides under vacuum will be discussed.     

Self‐Assembly,Spectroscopic and Electrochemical Studies of Nickel(II)‐4,8‐Diazaundecanediamide Complex

The self‐assembly of NiCl₂·6H₂O with a diaminodiamide ligand 4,8‐diazaundecanediamide (L‐2,3,2) gave a [Ni(C₉H₂₀N₄O₂)(Cl)(H₂O)] Cl·2H₂O ( 1 ). The structure of 1 was characterized by single‐crystal X‐ray diffraction analysis. Structural data for 1 indicate that the Ni(II) is coordinated to two tertiary N atoms, two O atoms, one water and one chloride in a distorted octahedral geometry. Crystal data for 1: orthorhombic, space group P 21nb, a = 9.5796(3) Å, b = 12.3463(4) Å, c = 14.6305(5) Å, Z = 4. Through NH···Cl–Ni (H···Cl 2.42 Å, N···Cl 3.24 Å, NH···Cl 158°) and OH···Cl–Ni contacts (H···Cl 2.36 Å, O···Cl 3.08 Å, OH···Cl 143°), each cationic moiety [Ni(C₉H₂₀N₄O₂) (Cl)(H₂O)]⁺ in 1 is linked to neighboring ones, producing a charged hydrogen‐bonded 1D chainlike structure. Thermogrametric analysis of compound 1 is consistent with the crystallographic observations. The electronic absorption spectrum of Ni(L‐2,3,2)²⁺ in aqueous solution shows four absorption bands, which are assigned to the ³A_2g → ³T_2g, ³T_2g → ¹Eg, ³T_2g → ³T_1g, and ³A_2g → ³T_1g transitions of triplet‐ground state, distorted octahedral nickel(II) complex. The cyclic volammetric measurement shows that Ni²⁺ is more easily reduced than Ni(L‐2,3,2)²⁺ in aqueous solution.     

Synthesis,Crystal Structure,and Hydrogen Bonding of μ‐Hydroxo‐μ‐peroxo‐bis[bis(ethylenediamine)cobalt(III)] Squarate

Black‐brown needle‐shaped single crystals of [Co₂(en)₄(O₂)(OH)][C₄O₄]_1.5 · 4H₂O (en = ethylenediamine) were prepared in aqueous solution at room temperature [space group P$\bar{1}$ (no.2) with a = 800.20(8), b = 1225.48(7), c = 1403.84(9) pm, α = 100.282(5), β = 94.515(7), and γ = 95.596(6)°]. The Co³⁺ cations [Co(1), Co(2)] are coordinated in an octahedral manner by four nitrogen atoms stemming from the ethylenediamine molecules and two oxygen atoms each from a hydroxo group and a peroxo group, respectively. Both Co³⁺ coordination polyhedra are connected by a common corner and by the peroxo group leading to the dinuclear [(en)₂Co(O₂)(OH)Co(en)₂]³⁺ cation. The squarate dianions, not bonded to Co³⁺, and the [(en)₂Co(O₂)(OH)Co(en)₂]³⁺ cations are linked by hydrogen bonds forming a three‐dimensional supramolecular network containing water molecules. Magnetic measurements revealed a diamagnetic behavior indicating a low‐spin electron configuration of Co³⁺. The UV/Vis spectra show two LMCT bands [π*(O₂^2–) → d_σ*(Co³⁺)] at 274 and 368 nm and the d–d transition (¹A_1g → ¹T_1g) at 542 nm. Thermoanalytical investigations in air show that the compound is stable up to 120 °C. Subsequent decomposition processes to cobalt oxide are finished at 460 °C.     

Gas‐phase reactions of Cl atoms with propane,n‐butane,and isobutane

Using the relative kinetic method, rate coefficients have been determined for the gas‐phase reactions of chlorine atoms with propane, n‐butane, and isobutane at total pressure of 100 Torr and the temperature range of 295–469 K. The Cl₂ photolysis (λ = 420 nm) was used to generate Cl atoms in the presence of ethane as the reference compound. The experiments have been carried out using GC product analysis and the following rate constant expressions (in cm³ molecule^?1 s^?1) have been derived: (7.4 ± 0.2) × 10^?11 exp [‐(70 ± 11)/ T], Cl + C₃H₈ → HCl + CH₃CH₂CH₂; (5.1 ± 0.5) × 10^?11 exp [(104 ± 32)/ T], Cl + C₃H₈ → HCl + CH₃CHCH₃; (7.3 ± 0.2) × 10^?11 exp[?(68 ± 10)/ T], Cl + n‐C₄H₁₀ → HCl + CH₃ CH₂CH₂CH₂; (9.9 ± 2.2) × 10^?11 exp[(106 ± 75)/ T], Cl + n‐C₄H₁₀ → HCl + CH₃CH₂CHCH₃; (13.0 ± 1.8) × 10^?11 exp[?(104 ± 50)/ T], Cl + i‐C₄H₁₀ → HCl + CH₃CHCH₃CH₂; (2.9 ± 0.5) × 10^?11 exp[(155 ± 58)/ T], Cl + i‐C₄H₁₀ → HCl + CH₃CCH₃CH₃ (all error bars are ± 2σ precision). These studies provide a set of reaction rate constants allowing to determine the contribution of competing hydrogen abstractions from primary, secondary, or tertiary carbon atom in alkane molecule. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 651–658, 2002     

2′‐Deoxyimmunosine: a thiazolo[4,5‐d]pyrimidine nucleoside adopting the syn conformation

The title compound [systematic name: 5‐amino‐3‐(2‐deoxy‐β‐d ‐erythro‐pentofuranosyl)thiazolo[4,5‐d]pyrimidine‐2,7‐(3H,6H)‐dione], C₁₀H₁₂N₄O₅S, exhibits a syn glycosylic bond conformation, with a torsion angle χ of 61.0 (3)°. The furanose moiety adopts the N‐type sugar pucker (³T₄), with P = 33.0 (5)° and τ_m = 15.1 (1)°. The conformation at the exocyclic C4′—C5′ bond is +ap (trans), with the torsion angle γ = 176.71 (14)°. The extended structure is a three‐dimensional hydrogen‐bond network involving O—H...O and N—H...O hydrogen bonds.     

Zum Chemischen Transport von Cr2O3 mit Cl2 und mit HgCl2 ? Experimente und Modellrechungen

On the Chemical Transport of Cr₂O₃ with Cl₂ and with HgCl₂ — Experiments and Model Calculations The migration of Cr₂O₃ in a temperature gradient (1 000°C → 900°C) in the presence of low concentrations of chlorine and water (from the wall of silica ampoules) is a result from the endothermic reactions (1) Cr₂O_3,s + H₂O_g + 3 Cl_2,g = 2 CrO₂Cl_2,g + 2 HCl_g (2) Cr₂O_3,s + 1/2 O_2,g + 2 Cl_2,g = 2 CrO₂Cl_2,g With higher concentrations of chlorine, the transport reaction is (3) Cr₂O_3,s + 5/2 Cl_2,g = 3/2 CrO₂Cl_2,g + 1/2 CrCl_4,g The gas phase of the transport system Cr₂O₃/Cl₂ can be reduced step by step by adding small amounts of chromium, so that CrCl₃ and finally also CrCl₂ become more important. Further, at a lower ratio n°(Cl)/n°(Cr) three transport reactions have to be taken into consideration; with the participation of CrOCl_2,g (5). (4) Cr₂O_3,s + 9/2 CrCl_4,g = 3/2 CrO₂Cl_2,g + 5 CrCl_3,g (5) Cr₂O_3,s + 3 CrCl_4,g = 3 CrOCl_2,g + 2 CrCl_3,g (6) Cr₂O_3,s + H_2,g + 4 HCl_g = 2 CrCl_2,g + 3 H₂O_g The reactions (1), (2) and (6) become possible through the cooperation of two transport agents at a time. The migration of Cr₂O₃ with HgCl₂ can also be described with reactions (1) – (3). The decomposition of HgCl₂ Produces the small chlorine pressure for the transport reaction. The oxidation potential of the transport agent HgCl₂ is too low for the oxidation of Cr^III to Cr^VI.     

Formation of Cr(II) Species in the H2/CrO3 System. Parameter control

The thermal behaviour of CrO₃ on heating up to 600°C in dynamic atmospheres of air, N₂ and H₂ was examined by thermogravimetry (TG), differential thermal analysis (DTA), IR spectroscopy and diffuse reflectance spectroscopy (DRS). The results revealed three major thermal events, depending to different extents on the surrounding atmosphere: (i) melting of CrO₃ near 215°C (independent of the atmosphere), (ii) decomposition into Cr₂(CrO₄)₃ at 340–360°C (insignificantly dependent), and (iii) decomposition of the chromate into Cr₂O₃ at 415–490°C (significantly dependent). The decomposition CrO₃ → Cr₂(CrO₄)₃ is largely thermal and involves exothermic deoxygenation and polymerization reactions, whereas the decomposition Cr₂(CrO₄)₃ → Cr₂O₃ involves endothermic reductive deoxygenation reactions in air (or N₂) which are greatly accelerated and rendered exothermic in the presence of H₂. TG measurements as a function of heating rate (2–50°C min⁻¹) demonstrated the acceleratory role of H₂, which extended to the formation of Cr(II) species. This could sustain a mechanism whereby H₂ molecules are considered to chemisorb dissociatively, and then spillover to induce the reduction. DTA measurements as a function of the heating rate (2–50°C min⁻¹) helped in the derivation of non-isothermal kinetic parameters strongly supportive of the mechanism envisaged. This revised version was published online in August 2006 with corrections to the Cover Date.     

The 7‐bromo derivative of 2‐amino‐2′‐deoxytubercidin fluorinated at the sugar moiety

The title compound, 2,4‐diamino‐5‐bromo‐7‐(2‐deoxy‐2‐fluoro‐β‐d ‐arabinofuranosyl)‐7H‐pyrrolo[2,3‐d]pyrimidine, C₁₁H₁₃BrFN₅O₃, shows two conformations of the exocyclic C4′—C5′ bond, with the torsion angle γ (O5′—C5′—C4′—C3′) being 170.1 (3)° for conformer 1 (occupancy 0.69) and 60.7 (7)° for conformer 2 (occupancy 0.31). The N‐glycosylic bond exhibits an anti conformation, with χ = −114.8 (4)°. The sugar pucker is N‐type (C3′‐endo; ³T₄), with P = 23.3 (4)° and τ_m = 36.5 (2)°. The compound forms a three‐dimensional network that is stabilized by several intermolecular hydrogen bonds (N—H...O, O—H...N and N—H...Br).     

Crystal structure,vibrational studies,optical properties,and Hirshfeld surface analysis of (C5H6N5)2[Cr2O7]

Single crystals of a new organic–inorganic compound, (C₅H₆N₅)₂Cr₂O₇ (1), adeninium dichromate, were grown by the slow evaporation technique and characterized by X-ray diffraction, infrared absorption, and the optical properties were also investigated by UV-vis absorption spectroscopy. The compound crystallizes in the triclinic system and P-1 space group with a = 11.6850(2) Å, b = 11.7531(5) Å, c = 14.5603(7) Å, α = 83.956(3)°, β = 70.481(4)°, γ = 61.863(2)°, V = 1658.70(12) Å³. The structure of the compound consists of four adeninium, (C₅H₅N₂)⁺, cations, and two dichromate dianions with all the atoms situated in general positions. Each dichromate anion is formed by two tetrahedral CrO₄ joined through shared O atoms and are linked to the cations with several weak hydrogen bonding interactions resulting in an extended network. 3-D Hirshfeld surface analysis and 2-D fingerprint plots indicate that the packing is dominated by H?O/O?H and H?N/N?H contacts.     

6‐Aza‐2′‐deoxy‐2′‐arabino­fluoro­uridine,a 2′‐deoxy­ribonucleoside with an N‐sugar conformation in the solid state and in solution

In the title compound, 2‐(2‐deoxy‐2‐fluoro‐β‐d ‐arabino­fur­anosyl)‐1,2,4‐triazine‐3,5(2H,4H)‐dione, C₈H₁₀FN₃O₅, the torsion angle of the N‐gly­cosylic bond is anti [χ = −125.37 (13)°]. The furan­ose moiety adopts the N‐type sugar pucker (³T₂), with P = 359.2° and τ_m = 31.4°. The conformation around the C4′—C5′ bond is antiperiplanar (trans), with a torsion angle γ of 177.00 (11)°. A network is formed via hydrogen bonds from the nucleobases to the sugar residues, as well as through hydrogen bonds between the sugar moieties.     

Ozone–olefin reactions in the gas phase 1. Rate constants and activation energies

Reactions of ozone with simple olefins have been studied between 6 and 800 mtorr total pressure in a 220-m³ reactor. Rate constants for the removal of ozone by an excess of olefin in the presence of 150 mtorr oxygen were determined over the temperature range 280 to 360° K by continuous optical absorption measurements at 2537 Å. The technique was tested by measuring the rate constants k₁ and k₂ of the reactions (1) NO + O₃ → NO₂ + O₂ and (2) NO₂ + O₃ rarr; NO₃ + O₂ which are known from the literature. The results for NO, NO₂, C₂H₄, C₃H₆, 2-butene (mixture of the isomers), 1,3→butadiene, isobutene, and 1,1 -difluoro-ethylene are 1.7 × 10^{?1 4} (290°K), 3.24 × 10^?17 (289°K), 1.2 × 10^{?1 4} exp (–4.95 ± 0.20/RT), 1.1 × 10^{?1 4} exp (–3.91 ± 0.20/RT), 0.94 × 10^{?1 4} exp ( –2.28 ± 0.15/RT), 5.45 ± 10^{?1 4} exp ( –5.33 ± 0.20/RT), 1.8 ×10^?17 (283°K), and 8 × 10^?20 cm³/molecule ·s(290°K). Productformation from the ozone–propylene reaction was studied by a mass spectrometric technique. The stoichiometry of the reaction is near unity in the presence of molecular oxygen.     

Polyol-Komplexe. VIII. R,R-trans-1,2-Diaminocyclohexan-κN,N′-(methyl-β-D-xylopyranosid-2,3-ato-κO2,O3)-aqua-kupfer-Dihydrat, [(R,R-chxn)(H2O)Cu(Me-β-D-Xylp2,3 H−2)] · 2 H2O, — ein Kupferkomplex mit einem doppelt deprotonierten D-Xylosederivat als Ligand

Polyol Metal Complexes. VIII. R,R-trans-Diaminocyclohexane-κN,N′ Methyl-β-D-xylopyranosid-2,3-ato-κO²,O³ Aqua Copper Dihydrate, [(R,R-chxn)(H₂O)Cu(Me-β-D-Xylp2,3 H_?2)] · 2 H₂O, — a Copper Complex with a Twofold Deprotonated Xylose Derivative as a Ligand Methyl β-D-xylopyranoside forms a chelate complex with copper(II) ions in aqueous, alkaline solution after deprotonation at O-2 and O-3. In the blue crystals, Cu^II is further coordinated by R,R-trans-1,2-diaminocyclohexane and water; P2₁, a = 982.9(3), b = 705.8(5), c = 1 292.1(6) pm, β = 96.74(4)°, V = 890.2(8) · 10⁶ pm³. The alkoxide-O-atoms act as acceptors in a hydrogen bond system, a typical feature of which is a homodromic helix of water molecules.     

7‐Amino‐1‐(2‐deoxy‐β‐erythro‐pentofuranosyl)‐1H‐1,2,3‐triazolo[4,5‐d]pyrimidine: an 8‐azaadenine nucleoside with the nucleobase in a syn conformation

The title compound, C₉H₁₂N₆O₃, shows a syn‐glycosylic bond orientation [χ = 64.17 (16)°]. The 2′‐deoxyfuranosyl moiety exhibits an unusual C1′‐exo–O4′‐endo (₁T⁰; S‐type) sugar pucker, with P = 111.5 (1)° and τ_m = 40.3 (1)°. The conformation at the exocyclic C4′—C5′ bond is +sc (gauche), with γ = 64.4 (1)°. The two‐dimensional hydrogen‐bonded network is built from intermolecular N—H...O and O—H...N hydrogen bonds. An intramolecular bifurcated hydrogen bond, with an amino N—H group as hydrogen‐bond donor and the ring and hydroxymethyl O atoms of the sugar moiety as acceptors, constrains the overall conformation of the nucleoside.     

2′‐Deoxy‐5‐fluorotubercidin

In the title compound, 4‐amino‐7‐(2‐deoxy‐β‐d ‐erythro‐pentofuranosyl)‐5‐fluoro‐7H‐pyrrolo[2,3‐d]pyrimidine, C₁₁H₁₃FN₄O₃, the conformation of the glycosyl bond lies between anti and high anti [χ = −101.1 (3)°]. The furanose moiety adopts the S‐type sugar pucker (²T₃), with P = 164.7 (3)° and τ = 40.1 (2)°. The extended structure is a three‐dimensional hydrogen‐bond network involving a C—H⋯F, two N—H⋯O and two O—H⋯O hydrogen bonds.     

Synthesis,Crystal Structure,and NMR Spectroscopy of a New P-Phenylenediamonium Diphosphate [p-NH3C6H4NH3]H2P2O7

Crystal growth and characterization by X-ray diffraction and NMR spectroscopy of a new p-phenylenediamonium diphosphate [p-NH₃ C ₆ H ₄ NH ₃]H ₂ P ₂ O ₇ are reported. This compound crystallizes in a triclinic unit cell P1 with the parameters a = 7.130(3), b = 9.047(3), c = 9.350(2) Å, α = 133.44(2)°, β = 95.02(2)°, γ = 107.11(4)°, Z = 2, V = 514.3(15) ų, and D _x = 1.848 g.cm^{? 3}. The crystal structure has been solved and refined to R = 0.0273, using 3678 independent reflections. The atomic arrangement is build up by infinite ribbons of [H₂ P ₂ O ₇] ^2? anions, extending along the a-direction at y = 1/2. Between these ribbons are located the p-phenylenediammonium entities, which form hydrogen bonds N─H…O with some external oxygen atoms of phosphoric groups. Crystallographic results are correlated with that of the solid state ¹³C and ³¹P MAS NMR spectroscopy.     

Synthesis and Characterization of Three Zinc Phosphonates Based on 5‐Phosphonoisophthalic Acid, (HO2C)2C6H3PO3H2

Three new Zn‐phosphonates based on 5‐phosphonoisophthalic acid, (HO₂C)₂C₆H₃PO₃H₂ (H₄L), [Zn₂(H₂O)(O₂C)₂C₆H₃PO₃] · H₂O ( 1 ), Zn₂(H₂O)₂(O₂C)₂C₆H₃PO₃ ( 2 ), and KZn[H(O₂C)₂C₆H₃PO₃] ( 3 ) have been hydrothermally synthesized and characterized by single‐crystal X‐ray diffraction ( 1 : triclinic, , a = 742.49(3) pm, b = 846.37(4) pm, c = 992.84(4) pm, α = 80.936(2)°, β = 81.574(2)°, γ = 73.139(3)°, V = 586.28(4) · 10⁶ pm³, R1 = 0.0583, wR2 = 0.1347 (for I > 2σ(I)); 2 : monoclinic, P2₁/m, a = 464.78(9) pm, b = 1329.2(3) pm, c = 974.5(3) pm, β = 95.80(3)°, V = 599.0(2) · 10⁶ pm³, R1 = 0.0395, wR2 = 0.1086 (for I > 2σ(I)); 3 : monoclinic, P2₁/c, a = 501.9(1) pm, b = 2489.9(5) pm, c = 946.2(5) pm, β = 105.38(3)°, V = 1140.0(7) · 10⁶ pm³, R1 = 0.0365, wR2 = 0.0848 (for I > 2σ(I))). The title compounds 1 and 2 have the same chemical composition but exhibit different structures and are therefore polymorphs. Thus, in compound 1 , isolated ZnO₄‐tetrahedra, and in 2 , infinite double‐chains of corner‐sharing ZnO₆ polyhedra are observed. In, KZn[H(O₂C)₂C₆H₃PO₃] ( 3 ) K⁺‐ions have been incorporated into the structure leading to the formation of a bimetallic inorganic‐organic hybrid compound.     

Zur Darstellung und Kristallstruktur von CrSO4 · 3 H2O

Preparation and Crystal Structure of CrSO₄ · 3 H₂O Evaporating a solution of Cr²⁺ in dilute sulphuric acid at 70°C light blue crystals of CrSO₄ · 3 H₂O were grown. Its x-ray powder diffraction pattern is quite similar to that of CuSO₄ · 3 H₂O. The crystal structure refinement of CrSO₄ · 3 H₂O (space group Ce, a = 5.7056(8) Å, b = 13.211(2) Å, c = 7.485(1) Å, β = 96.73(1)°, Z = 4) from single crystal data, using the parameters of the copper compound as starting values, results in a final R-value of R = 3.8%. The surrounding of the Cr²⁺ ion can be described as a strongly elongated octahedron. The basal plane of the CrO₆-octahedron consists of three hydrate oxygen atoms and one sulphate oxygen atom. The two more distant axial oxygen atoms also belong to sulphate groups. Thus they are forming chains of alterning CrO₆-octahedra and SO₄-tetrahedra along [110] and [1–10] linked via common corners. These chains are connected via sulphate groups and by bridging hydrogen bonds to a 3-dimensional network.     

4,4′‐Tri­methyl­enedipyridinium bis­[carboxy­methyl­phos­pho­nate(1–)]: a three‐dimensional framework structure built from O—H⃛O,N—H⃛O and C—H⃛O hydrogen bonds

In the title compound, C₁₃H₁₆N₂²⁺·2C₂H₄O₅P⁻, the cation lies across a twofold rotation axis in space group Fdd2. The anions are linked into molecular ladders by two O—H⃛O hydrogen bonds [H⃛O = 1.73 and 1.77 Å, O⃛O = 2.538 (2) and 2.598 (3) Å, and O—H⃛O = 160 and 170°], these ladders are linked into sheets by a single type of N—H⃛O hydrogen bond [H⃛O = 1.75 Å, N⃛O = 2.624 (3) Å and N—H⃛O = 171°] and the sheets are linked into a three‐dimensional framework by a single type of C—H⃛O hydrogen bond [H⃛O = 2.48 Å, C⃛O = 3.419 (4) Å and C—H⃛O = 167°].     

7‐Deaza‐2,8‐diaza­adenosine

In the title compound [systematic name: 4‐amino‐7‐(β‐d ‐ribofuranos­yl)‐7H‐pyrazolo[3,4‐d][1,2,3]triazine], C₉H₁₂N₆O₄, the torsion angle of the N‐glycosylic bond is high anti [χ = −83.2 (3)°]. The ribofuran­ose moiety adopts the C2′‐endo–C1′‐exo (²T₁) sugar conformation (S‐type sugar pucker), with P = 152.4° and τ_m = 35.0°. The conformation at the C4′—C5′ bond is +sc (gauche,gauche), with the torsion angle γ = 52.0 (3)°. The compound forms a three‐dimensional network that is stabilized by several hydrogen bonds (N—H⋯O, O—H⋯N and O—H⋯O).