Novel Motif of Hydrogen Bonds in the Water-assisted Supramolecular Self-assembly of 2-acetylamino-6-methylpyridine-N-oxide and Hetero-assembly of 1:1 Co-crystal of o-Phenylenediamine with Catechol

Abstract

Water assisted supramolecular structures of 2-acetylamino-6-methylpyridine-1-oxide (1) and 1:1 complex of o-phenylenediamine with catechol (2) were determined. The crystal structure of 2-acetylamino-6-methylpyridine-1-oxide. H₂O (1), triclinic, a = 7.1276 (6), b = 7.8860 (6), c = 8.9938 (7) Å, α = 100. 143 (2), β = 91.493 (2), γ = 110.972 (1)°, V =462.47 (6) ų, Z = 2, D _calc = 1.323 mg.m^?3(293°K) reveals a novel centrosymmetric supramolecular assembly that is sustained by water molecules linking the dimers of pyridine-1-oxide through C—H…O, N—H…O, N⁺—O^? … H hydrogen bonds. The pyridine rings of the dimers are stacked at 3.473 Å apart, involving π- stacking interactions. Complex (2), C₆H₈N₂.—C₆ H₆O₂. 1/2H₂O crystallises in the monoclinic space group P2/c: a = 9.0498(2), b = 5.2275(1), c = 25.0771(2) A, β = 97.71°, V= 1175.62(4) ų, Z = 4. Refinement led to a final conventional R value of 0.041 for 2016 reflections. In these crystals (2), the water molecules lie on the twofold axis and they are linked to the pyrocatechol molecules through an O—H…O hydrogen bond.     

The Structure of cis‐[Chloro(dimethylsulfoxide)bis(1, 10‐phenanthroline)ruthenium(II)]‐tetraphenylborate, [RuCl(DMSO)(1, 10‐phen)2][BPh4]

The complex cis‐[RuCl(DMSO)(phen)₂]BPh₄, where DMSO is dimethylsulfoxide and phen is 1, 10‐phenanthroline, crystallizes in the monoclinic space group P2₁/c with a = 19.505(4), b = 10.045(2), c = 21.199(4) Å, β = 90.137(4)°, V = 4153(2) ų, Z = 4, D_calc = 1.430 g cm^—3. The ruthenium coordination geometry is that of a slightly distorted octahedron with a cis‐RuN₄ClS arrangement of the ligand donor atoms. The Ru—Cl distance is 2.421(1) Å and the Ru—S distance 2.250(2) Å. The four Ru—N distances are 2.057(6), 2.066(4), 2.073(4), and 2.086(4) Å with the Ru—N bond trans to Cl the second shortest and the Ru—N bond trans to S the longest one.     

Synthesis,Characterization and Explosive Properties of 1,3‐Dimethyl‐5‐amino‐1H‐tetrazolium 5‐Nitrotetrazolate

1,3‐Dimethyl‐5‐amino‐1H‐tetrazolium 5‐nitrotetrazolate ( 5b ) was synthesized in high yield from 1,4‐dimethyl‐5‐amino‐1H‐tetrazolium iodide ( 5a ) and silver 5‐nitrotetrazolate. Both new compounds ( 5a and 5b ) were characterized using vibrational (IR and Raman) and multinuclear NMR spectroscopy (¹H, ¹³C and ¹⁵N), elemental analysis and single‐crystal X‐ray diffraction. 5a crystallizes in an orthorhombic cell: Pbca, a = 11.5016(4), b = 13.7744(5), c = 13.7744(5) Å, V = 1638.2(1) ų, Z = 8, ρ = 1.955 g cm^?3, R₁ = 0.0210 (F > 4σ(F)), wR₂ (all data) = 0.0542; whereas 5b crystallizes in a monoclinic cell: C1c, a = 14.5228(8), b = 5.0347(2), c = 13.7217(7) Å, β = 112.11(1)°, V = 929.6(2) ų, Z = 4, ρ = 1.630 g cm^?3, R₁ = 0.0279 (F > 4σ(F)), wR₂ (all data) = 0.0585. The sensitivity of 5b to classical stimuli was determined by using standard BAM tests and its thermal stability was assessed by DSC measurements. In addition, its heat of combustion was determined by bomb calorimetry measurements. The EXPLO5 was used to calculate the detonation pressure (P) and velocity (D) of 5b (P = 13.3 GPa and D = 6379 m s^?1), as well as those of its mixtures with ammonium nitrate (P = 23.2 GPa and D = 7862 m s^?1) and ammonium dinitramide (P = 29.6 GPa and D = 8594 m s^?1). Compound 5b is a hydrolytically stable solid with a high melting point (160 °C) and thermally stable to 190 °C with a very low sensitivity to friction (>360 N) and impact (>30 J) and good performance in combination with an oxidizer making it of interest in new environmentally friendly, insensitive explosive formulations.     

Effects on Coordination of Thioether Sites. 4. Structural Analysis of η3-Tripodal Ligand Manganese(I) Complexes

Crystal structures of a series of manganese(I) complexes containing tripodal ligands were determined. For [η³-{CH₃C(CH₂PPh₂)₂(CH₂SPh)-P,P′,S}Mn(CO)₃]PF₆ ( 1 ): a = 10.856(3) Å, b = 19.698(3) Å, c = 17.596(5) Å, β = 96.17(2)°, monoclinic, Z = 4, P2₁/c, R(F_o) = 0.068, R_w(F_o) = 0.055 for 3617 reflections with I_o > 2σ(I_o). For [η³-{CH₃C(CH₂PPh₂)(CH₂SPh)₂-P,P′,S}Mn(CO)₃]PF₆ ( 2 ): a = 9.890(2) Å, b = 20.403(4) Å, c = 10.269(3) Å, β = 117.44(2)°, monoclinic, Z = 2, P2_l, R(F_o) = 0.050, R_w(F_o) = 0.037 for 1760 reflections with I_o > 2σ(I_o). For [η³-{CH₃C(CH₂PPh₂)₂(CH₂S)-P,P′,S}Mn(CO)₃] ( 4 ): a = 8.191(7) Å, b = 10.495(3) Å, c = 19.858(6) Å, α = 99.61(2)°, β = 96.17(2)°, γ = 92.70(4)°, triclinic, Z = 2, P-I, R(F_o) = 0.048, R_w(F_o) = 0.039 for 2973 reflections with I_o > 2σ(I_o). There is no significant difference in the bond lengths of Mn-S bonds among three species in their crystal structures [2.325(2) Å in 1; 2.358(4) in 2; 2.380(2) in 4], but the better donating ability of thiolate in complex 4 appears on the lower frequencies of its carbonyl stretching absorptions.     

Structural Characterization and Thermal Behavior of 1-Amino-1-methylamino-2,2-dinitroethylene

A novel high energetic material, 1‐amino‐1‐methylamino‐2,2‐dinitroethylene (AMFOX‐7), was synthesized through 1,1‐diamino‐2,2‐dinitroethylene (FOX‐7) reacting with methylamine in N‐methyl pyrrolidone (NMP) at 80.0°C, and its structure was determined by single crystal X‐ray diffraction. The crystal is monoclinic, space group P2₁/m with crystal parameters of a=6.361(3) Å, b=7.462(4) Å, c=6.788(3) Å, β=107.367(9)°, V=307.5(3) ų, Z=2, µ=0.160 mm^?1, F(000)=168, D_c=1.751 g·cm^?3, R₁=0.0463 and wR₂=0.1102. Thermal decomposition of AMFOX‐7 was studied, and the enthalpy, apparent activation energy and pre‐exponential constant of the exothermic decomposition reaction are 303.0 kJ·mol^?1, 230.7 kJ·mol^?1 and 10^21.03 s^?1, respectively. The critical temperature of thermal explosion is 245.3°C. AMFOX‐7 has higher thermal stability than FOX‐7.     

Synthesis,crystal structure and magnetic properties of Co(NIT4Py)(H2PDA)(H2O)3

A Co(II)-pyridyl substituted nitronyl nitroxide complex Co(NIT4Py)(H₂PDA)(H₂O)₃ has been synthesized and structurally characterized (NIT4Py: 2-(4′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and H₂PDA: 2,5-pyridine dicarboxylic acid). The compound is in the monoclinic space group P2(1)/c, a = 16.892(5) Å, b = 7.371(2) Å, c = 18.856(5) Å, β = 108.770(5)°, V = 2223.0(11) ų, Z = 4 and F(000) = 1064. The cobalt is in a distorted octahedral environment with one nitrogen from NIT4Py, one oxygen atom from H₂PDA, two oxygens from two water molecules in the basal plane and one nitrogen from H₂PDA and one water in the axial positions. The molecules are connected as a layered structure by intermolecular hydrogen bond interactions. Variable temperature magnetic susceptibility measurements reveal the occurrence of weak antiferromagnetic interactions in the compound.     

Synthese und Kristallstruktur von Na2Zn(OH)4

Synthesis and Crystal Structure of Na₂Zn(OH)₄ Crystallization from saturated sodium hydroxozincate solutions yields colourless platelets of crystals of Na₂Zn(OH)₄. The X‐ray structure determination on these crystals was successful including all hydrogen positions. P2₁/n, Z = 4, a = 7.959(3) Å, b = 6.534(1) Å, c = 8.501(3) Å, β = 93.97(3)°, N(F²_o ° 2σ F²_o) = 1668, N(Var.) = 81, R₁/wR₂ = 0.043/0.107. Na₂Zn(OH)₄ crystallizes in a layered structure. Alternate layers contain Na⁺ in octahedral and Zn²⁺ in tetrahedral coordination by OH^–.     

2,3:4,6‐Di‐O‐isopropylidene‐α‐l‐sorbofuranose and 2,3‐O‐isopropylidene‐α‐l‐sorbofuranose

In the title compounds, C₁₂H₂₀O₆, (I), and C₉H₁₆O₆, (II), the five‐membered furanose ring adopts a ⁴T₃ conformation and the five‐membered 1,3‐dioxolane ring adopts an E₃ conformation. The six‐membered 1,3‐dioxane ring in (I) adopts an almost ideal ^OC₃ conformation. The hydrogen‐bonding patterns for these compounds differ substantially: (I) features just one intramolecular O—H...O hydrogen bond [O...O = 2.933 (3) Å], whereas (II) exhibits, apart from the corresponding intramolecular O—H...O hydrogen bond [O...O = 2.7638 (13) Å], two intermolecular bonds of this type [O...O = 2.7708 (13) and 2.7730 (12) Å]. This study illustrates both the similarity between the conformations of furanose, 1,3‐dioxolane and 1,3‐dioxane rings in analogous isopropylidene‐substituted carbohydrate structures and the only negligible influence of the presence of a 1,3‐dioxane ring on the conformations of furanose and 1,3‐dioxolane rings. In addition, in comparison with reported analogs, replacement of the –CH₂OH group at the C1‐furanose position by another group can considerably affect the conformation of the 1,3‐dioxolane ring.     

Darstellung und Eigenschaften von Tetra(n-butyl)ammonium-cis-trifluorophthalocyaninato(2–)zirconat(IV) und -hafnat(IV); Kristallstruktur von (nBu4N)cis[Hf(F)3pc2–]

Preparation and Properties of Tetra(n-butyl)ammonium cis -Trifluorophthalocyaninato(2–)zirconate(IV) and -hafnate(IV); Crystal Structure of (ⁿBu₄N) ^cis [Hf(F)₃pc^2–] cis-Dichlorophthalocyaninato(2–)metal(IV) of zirconium and hafnium reacts with excess tetra(n-butyl)-ammoniumfluoride trihydrate to yield tetra(n-butyl)-ammonium cis-trifluorophthalocyaninato(2–)metalate(IV), (ⁿBu₄N)^cis[M(F)₃pc^2–] (M = Zr, Hf). (ⁿBu₄N)^cis[Hf(F)₃pc^2–] crystallizes in the monoclinic space group P2₁/n (# 14) with cell parameters a = 13.517(1) Å, b = 13.856(1) Å, c = 23.384(2) Å, α = 92.67(1)°, Z = 4. The Hf atom is in a ”︁square base-trigonal cap”︁”︁ polyhedron, coordinating three fluorine atoms and four isoindole nitrogen atoms (N_iso). The Hf atom is sandwiched between the (N_iso)₄ and F₃ planes (d(Hf–Ct_N) = 1.218(3) Å; d(Hf–Ct_F) = 1.229(3) Å; Ct_N/F: centre of the (N_iso)₄, respectively F₃ plane). The average Hf–N_iso and Hf–F distances are 2.298 and 1.964 Å, respectively, the average F–Hf–F angle is 84.9°. The pc^2– ligand is concavely distorted. The optical spectra show the typical metal independent π-π* transitions of the pc^2– ligand at c. 14700 and 29000 cm^–1. In the FIR/MIR spectra vibrations of the MF₃ skeleton are detected at 545, 489, 274 cm^–1 (M = Zr) and 536, 484, 263 cm^–1 (M = Hf), respectively.     

SYNTHESIS OF A DINUCLEAR YLID COMPLEX DERIVED FROM P(OPh)3: CRYSTAL STRUCTURES OF [Cp2Fe2(CO)2(μ-CO) (μ-CHP(OPh)3)+][BF4 −] AND [Cp2Fe2(CO)2 (μ-CO)(μ-CHPPh3)+][BF4 −]

Abstract

[Cp₂Fe₂(CO)₂(μ-CO)(μ-CHP(OPh)₃)⁺][BF^? ₄] crystallizes in the centrosymmetric monoclinic space group P2₁/n with a = 12.553(7) Å, b = 16.572(11) Å, c = 15.112(8) Å, β = 100.00(4)°, V = 3096(3) ų and D(calcd.) = 1.579 g/cm³ for Z = 4. The structure was refined to R(F) = 5.83% for 1972 reflections above 4σ(F). The cation contains two CpFe(CO) fragments linked via an iron—iron bond (Fe(1)—Fe(2) = 2.544(3)Å), a bridging carbonyl ligand (Fe(1)—C(4) = 1.918(1) Å, Fe(2)—C(4) = 1.946(12)Å) and a bridging CHP(OPh)₃ ligand (Fe(1)—C(1) = 1.980(9)Å, Fe(2)—C(1) = 1.989(8)Å). Distances within the μ-CHP(OPh)₃ moiety include a rather short carbon—phosphorus bond [C(1)—P(1) = 1.680(10)Å] and P—O bond lengths of 1.550(7)–1.579(6)Å. The crystal is stabilized by a network of F…H—C interactions involving the BF^? ₄ anion.

[Cp₂Fe₂(CO)₂(μ-CO)(μ-CHPPh₃)⁺][BF^? ₄], which differs from the previous compound only in having a μ-CHPPh₃ (rather than μ-CHP(OPh)₃) ligand, crystallizes in the centrosymmetric monoclinic space group P2₁/c with a = 11.248(5)Å, b = 13.855(5)Å, c = 18.920(7)Å, β = 96.25(3)°, V = 2931(2)ų and D(calcd.) = 1.559 g/cm³ for Z = 4. This structure was refined to R(F) = 4.66% for 1985 reflections above 4σ(F). Bond lengths within the dinuclear cation here include Fe(1)-Fe(2) = 2.529(2)Å, Fe(1)—C(3) = 1.904(9) Å and Fe(2)—C(3) = 1.911(8) Å (for the bridging CO ligand) and Fe(1)—C(1P) = 1.995(6) Å and Fe(2)—C(1P) = 1.981(7) Å (for the bridging CHPPh₃ ligand). Distances within the μ-CHPPh₃ ligand include a longer carbon—phosphorus bond [C(1P)—P(1) = 1.768(6)Å] and P(1)—C(phenyl) = 1.797(7)–1.815(8) Å.     

3-D frameworks assembled by lanthanide dimers with 1,4-cyclohexanedicarboxylic acid and 1,10-phenanthroline via hydrogen bonds and π–π stacking interactions

Two complexes [Ln(e,a-cis-1,4-chdc)(e,a-cis-1,4-Hchdc)(phen)(H₂O)]₂?10H₂O (Ln = Eu, 1; Tb, 2, 1,4-H₂chdc = 1,4-cyclohexanedicarboxylic acid; phen = 1,10-phenanthroline) have been synthesized and structurally characterized by single-crystal X-ray diffraction. Both complexes are doubly e,a-cis-1,4-chdc-bridged dimers. The e,a-cis-1,4-Hchdc, phen, and water molecules bond to Ln³⁺, forming nine-coordinate complexes. 3-D supramolecular frameworks are constructed by hydrogen bonds and π–π stacking interactions. Luminescence spectra exhibit the ⁵D₀ → ⁷F _J (J = 0–4) and ⁵D₄ → ⁷F _J (J = 6–3) transitions of Eu³⁺ for 1 and Tb³⁺ ion for 2, respectively.     

Na5Br(OH)4: Darstellung und Kristallstruktur einer Verbindung im System NaOH/NaBr

Na₅Br(OH)₄: Synthesis and Structure of a Compound in the System NaOH/NaBr The pseudobinary system NaOH/NaBr is investigated by X-ray methods. The structure of the compound Na₅Br(OH)₄ was solved by single crystal data: Na₅Br(OH)₄: Pnma, Z = 8, a = 11.846(2) Å, b = 18.782(4) Å, c = 6.431(1) Å, Z(F_o) = 1 202 with (F_o)² ≥ 3σ(F_o)², Z(parameter) = 100, R/R_w = 0.030/0.035 The compound crystallizes in a new type of structure. Pairs of octahedra around O by 5 Na and 1 H to [Na₅(OH)]₂ are orientated in such a way to one another that two ions OH^? form a parallelogram hinting to unusual bent hydrogen bridge bonding.     

Crystal Structure of the Coordinatively Unsaturated 2-Pyridylphosphine Pd(0) Complex Pd(PPh2Py)3

The three-coordinate tris(2-pyridylphosphine)palladium(0) complex is the first example of a group 10 metal complex bearing pyridine substituted phosphine ligand, whose crystal structure is determined. Pd(PPh₂py)₃ crystallizes in the triclinic space group $ {\rm P}\bar 1 $, with a = 12.874(4) Å, b = 14.162(3) Å, c = 14.912(3) Å, α = 87.76(2)°, β = 66.50(2)°, γ = 63.17(2)°, Z = 2, and V = 2191(1) ų. Full-matrix least-squares refinement of 523 variables using 4911 data (F²_o > 3σF²_o) gave R = 0.033 and R_w = 0.033. The pyridine ring is disordered. Possible weak interactions among Ph rings or Py rings and Pd center are discussed. Close approach of the ortho hydrogen on phenyl rings to the Pd center may imply facile ortho metallation.     

Crystal Structures of Hydrazinium(II) Salts of [SbF6]– and [Sb2F11]–

N₂H₆(Sb₂F₁₁)₂ was synthesized by the reaction of N₂H₆F₂ with excess of SbF₅ in anhydrous hydrogen fluoride (aHF). It crystallizes in the triclinic space group P$\bar{1}$ (No. 2) with a = 6.6467(3) Å, b = 8.3039(4) Å, c = 8.3600(5) Å, α = 76.394(5) ^o, β = 70.161(5) ^o, γ = 70.797(5) ^o, V = 405.90(4) ų at 150 K, Z = 2. When it is redissolved in aHF, it solvolysis with the release of SbF₅ yielding N₂H₆(SbF₆)₂ which crystallizes in the monoclinic C2/c space group (No. 15) with a = 7.3805(3) Å, b = 12.3248(5) Å, c = 10.4992(4) Å, β = 92.218(4) ^o, V = 954.33(7) ų at 150 K, and Z = 8. No other phases were observed in crystallization products when different molar ratios of N₂H₆F₂/SbF₅ (1:1,2:3,1:3) in aHF were used as starting materials.     

Li2CrO4 · 2H2O: Ungewöhnliche Wasserstoffbrückenbindung und Koordination der O-Liganden des Anions CrO42−

Li₂CrO₄ · 2H₂O: Unusual Hydrogen Bridge Bonding and Coordination for Oxygen of the Anions CrO₄^2? The crystal structure of Li₂CrO₄ · 2H₂O was solved including the positions of hydrogen by X-ray methods. Li₂CrO₄ · 2H₂O: P2₁2₁2₁, Z = 4, a = 5.503(1) Å, b = 7.733(2) Å, c = 11.987(2) Å, Z(F_o) with (F_o)² ? 3σ(F_o)² = 2284, Z (parameter) = 99, R/R_w = 0.025/0.029 LiCrO₄ · 2H₂O contains a locally bordered hydrogen bridge bonding system between water molecules as donors and two O of CrO₄^2? as acceptors. This system connects anions in the direction [010]. It is noticeable that oxygen ligands of the anion CrO₄^2? have strongly differing coordination.     

Synthesis,Spectroscopic, and X‐Ray Diffraction Studies of cis‐Dichlorobis(4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl3 H‐pyrazol‐3‐onato) Tin(IV)

Reaction between an aqueous ethanol solution of tin(II) chloride and that of 4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl‐3 H‐pyrazol‐3‐one in the presence of O₂ gave the compound cis‐dichlorobis(4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl‐3 H‐pyrazol‐3‐onato) tin(IV) [(C₂₆H₂₆N₄O₄)SnCl₂]. The compound has a six‐coordinated Sn^IV centre in a distorted octahedral configuration with two chloro ligands in cis position. The tin atom is also at a pseudo two‐fold axis of inversion for both the ligand anions and the two cis‐chloro ligands. The orange compound crystallizes in the triclinic space group P 1 with unit cell dimensions, a = 8.741(3) Å, b = 12.325(7) Å, c = 13.922(7) Å; α = 71.59(4), β = 79.39(3), γ = 75.18(4); Z = 2 and D_x = 1.575 g cm^–3. The important bond distances in the chelate ring are Sn–O [2.041 to 2.103 Å], Sn–Cl [2.347 to 2.351 Å], C–O [1.261 to 1.289 Å] and C–C [1.401 Å] the bond angles are O–Sn–O 82.6 to 87.7° and Cl–Sn–Cl 97.59°. The UV, IR, ¹H NMR and ¹¹⁹Sn Mössbauer spectral data of the compound are reported and discussed.     

Conformational and solid-state studies of diphenyl 1-hydroxy-1-phenylethylphosphonate

The crystal structure of the title compound, diphenyl 1-hydroxy-1-phenylethylphosphonate ( 1 ), was determined by the single-crystal X-ray diffraction method. The crystallographic data for 1 are as follow: C₂₀H₁₉O₄P, M_r = 354.34, monoclinic, P2₁/n, a = 9.787(1) Å, b = 20.235(1) Å, c = 9.797(1) Å, β = 106.18(3)°, V = 1863.3(4) ų, Z = 4, D_calc = 1.26 g/cm³, λ(Mo-Ka) = 0.71073 Å, μ = 1.6 cm⁻¹, F(000) = 744, R = 0.018, and R_w = 0.032 for 2258 observed reflections. The solid-state structure in a dimeric packing mode exhibits intermolecular hydrogen bonding of the type P = O···H–O. Infrared solution studies (CCl₄) indicate that upon high dilution (10⁻⁴ M) the dimers completely dissociate to give conformers with and without intramolecular hydrogen bonds. Theoretical studies (PM3) were undertaken to determine the energy profile about the P–C torsional angle, which exhibited low energy barriers to rotation with no clear minimum energy conformation. © 1996 John Wiley & Sons, Inc.     

Conformational Studies of Dibenzo-30-crown-10 Complexes. Syntheses and Crystal Structures of Potassium and Ammonium Hexafluorophosphate Complexes

Abstract

Crown ether complexes formed by the dibenzo–30-crown–10 (DB30C10) with potassium and ammonium hexafluorophosphate have been prepared and their crystal structures have been determined by single crystal X-ray analyses. The potassium complex (compound 1) consists of [K(DB30C10)]⁺ cation and PF₆ ^? anion. Crystals are monoclinic, space group P2/n, with a = 11.9106(3), b = 9.8382(5), c = 14.3062(3) Å, β = 97.581(3)°, V = 1661.7(1) ų, D_c = 1.440 g cm^?3, Z = 4, R = 0.0675 for 2528 unique observed reflections. The potassium atom is coordinated to the ten oxygen atoms of the crown ligand at the distance from 2.859(3) to 2.930(3) Å. The ammonium complex (compound 2) has also 1:1 crown—cation ratio. Crystals are monoclinic, space group P2₁/n, with a = 12.5061(6), b = 19.3724(5), c = 14.2203(9) Å, β = 102.476(5)°, V = 3363.8(3) ų, D_c = 1.501 g cm^?3, Z = 4, R = 0.0677 for 4172 unique observed reflections. The ammonium cation is completely enclosed with crown oxygen atoms forming seven hydrogen bonds. The conformation of previously reported dibenzo-30-crown-10 complexes with potassium salts were investigated using polar coordinate maps.     

Synthesis,characterization, and X-ray crystallographic structure of 1,3-dimethyl-2(3H)-imidazoleselone

The reaction of elemental Se with 1,3-dimethylimidazolium iodide in methanolic K₂CO₃ yields 1,3-dimethyl-2(3H)-imidazoleselone for which three addition products, two with bromine and one with iodomethane, have been synthesized and for which X-ray crystallographic analysis shows the structure to consist of a selenium-substituted planar heterocyclic ring with bond distances and angles significantly different from those noted for the previously reported sulfur analog [1,3-dimethyl-2(3H)-imidazolethione, dmit]. Crystal data: C₅H₈N₂Se, space group C mcm, M = 175.03, a = 8.625(3), b = 11.447(6), c = 6.900(4) Å, V = 681.24 ų, Z = 4, D_c = 1.707 g cm⁻³, D₀ = 1.68 g cm⁻³, λ = 0.71073 Å (Mo-K_α), μ = 5.35 mm⁻¹, R = 0.034, and R_w = 0.031.     

Crystal and molecular structure of bis(N,N-dipropyl-N′-diphenoxythiophosphoryl-thioureato) nickel(II) [(C6H5O)2P(S)NC(S)N(C3H7)2]2Ni

The Ni complex [C₆H₅O₂P(S)N(C₃H₇₂]₂Ni is monoclinic, space group P2₁/n with a = 8.890(3), b = 21.692(5), c = 11.670(4) Å, β = 108.35(5)°, V = 2136(1) ų, F(000) = 916, M_r = 534.01, Z = 2, D_m = 1.318, D_x = 1.358 Mg m^?3, graphite monochromatized MoKα ^? radiation, π = 0.7107 Å, μ = 0.76 mm^?1, T = 293 K. The structure was solved by a heavy atom method and refined to R = 0.044 for 3095 independent reflexions. The Ni atom lies in the centre of symmetry and is coordinated by four S atoms of the two molecules of the ligand in a planar arrangement. Ni? S bond lengths are 2.205 and 2.226 Å resp., the angles S? Ni? S are 97.65 and 82.35° resp.