Disordered Crystal Structure of 4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacozane perchlorate

Crystals of the ionic complex (salt) of 4,7,13,16,21,24hexaoxa 1,10diazabicyclo[8.8.8]hexacozane perchlorate, [H₂(Crypt2.2.2)]²⁺ · 2ClO₄ ^-, were synthesized and studied by Xray structural analysis: space group C2/c, a = 20.198(3), b = 10.119(2), c = 12.938(2), = 90.97(1)°, Z = 4, 3030 measured independent reflections, R = 0.067. In these crystals, all atoms of the 2.2.2 dication are disordered over two positions with occupancies of 0.518(4) and 0.482(4). Two conformations of the disordered 2.2.2 dication are such that two H atoms at two nodal N atoms point to its cavity.     

Distortion of the Cucurbituril Molecule by an Included 4‐Methylpyridinum Cation

The crystal and molecular structures of a guest–host complex of cucurbituril with 4methylpyridinium, {(4MePyH) (C₃₆H₃₆N₂₄O₁₂)}(NO₃) · 4H₂O, were determined by Xray structural analysis. The crystals are monoclinic with a = 26.276(3) , b = 25.861(2) , c = 17.375(2) , = 124.17(1)°, V_cell =9768.6(18) ³, space group Cc, and Z = 8. The structure contains two crystallographically independent supramolecular complexes. They are arranged in pillars oriented along the a axis. In each pillar, the complexes are parallel to each other. The pillars are shifted with respect to each other by onehalf of the crystallographic translation. The centers of the supermolecules are arranged according to a pseudobodycentered motif. Distortions of the cucurbituril molecule depending on the guest type have been analyzed with the use of results obtained in the present and previous studies.     

Phase Transitions in Channel Clathrates of Thiourea with Hexachloroethane and Tetrachloroethane

An explanation is proposed for the nature of phase transitions in channel clathrates of thiourea with hexachloroethane and tetrachloroethane. Analysis of experimental temperature dependences of specific heat, entropy, and NQR spectra indicates the existence of first and secondorder phase transitions. In the thiourea + hexachloroethane compound, the secondorder phase transition (94.60 K, entropy gain Rln2) implies a transformation of two equiprobable states (lowtemperature phase) into a single new state (hightemperature phase). The firstorder phase transition corresponds to clathrate channel distortion. In the thiourea + tetrachloroethane compound, the secondorder phase transition (224K, entropy change Rln 6) occurs with transformation of six equiprobable states (lowtemperature phase) into a single new state (hightemperature phase). The firstorder phase transition corresponds to clathrate channel distortion. The next secondorder phase transition observed in this compound at 248 K leads to disappearance of the four possible orientations of guest molecules in the clathrate channel of hexagonal section and to a transition of guest molecules to chaotic orientation (entropy increment equals Rln 4).     

Structure and Magnetic Properties of Solid Solutions of Molecular Magnetics Based on Ni(II) and Co(II) Complexes with Nitroxyl Radicals

Ni(II) and Co(II) complexes with deprotonated paramagnetic enaminoketones 4(3,3,3trifluorine2oxopropylidene) 2,2,5,5tetramethyl3imidazolidine1oxyl (L) and 4(3,3,3trifluorine1chlorine2oxopropylidene)2,2,5,5tetramethyl3imidazolidine1oxyl (L¹) and alcohols are shown to form continuous solid solutions Ni_xCo_1-xL₂(C₂H₅OH)₂ and Ni_xCo_1-xL₂ ¹(CH₃OH)₂. Single crystal Xray diffraction analysis showed that concentration variation practically does not affect the structural characteristics of the solid solutions. Distinguishing features if the magnetic behavior of Ni_xCo_1-xL₂ · (C₂H₅OH)₂ and Ni_xCo_1-xL₂ ¹(CH₃OH)₂ are the antiferromagnetic interaction of the moments of the nickel and cobalt sublattices inside the polymeric layers and the antiferromagnetic nature of interlayer interaction of the magnetic moments.     

Recent progress in tartaric acid‐modified Raney nickel system for enantio‐differentiating hydrogenation

Tartaric acidmodified Raney nickel (TAMRNi) is an enantiodifferentiating catalyst for hydrogenation of ketones. The stereochemical models explaining the enantiodifferentiation of ketoester and 2alkanone were unified as an extended stereochemical model by the experimental supports. Based on this new model, a working hypothesis to improve the enantiomeric excess (ee) of the ketoester/TAMRNi system was developed, and the ee was improved to 96%. By further fine tuning of this system, almost perfect enantiodifferentiation resulting in over 98% ee was achieved.     

Crystal and Molecular Structure of 2,3‐Pentamethylene‐3,4‐Dihydroquinazolone‐4 Nitrate. Conjugation Effects in the Series of Tricyclic Quinazolines

The structure of 2,3pentamethylene3,4dihydroquinazolone4 nitrate was determined by means of Xray diffraction. Analysis was performed of the geometry of the heterocyclic ring in 2,3tri, tetra, and pentamethylene3,4dihydroquinazolones4, quinazolines, and their salts with inorganic acids and complexes with metal ions. It is found that in the N(1)—C(2)—N(3) fragment in the bases of quinazolines and quinazolones4, the conjugation is less pronounced than that in the protonated (salt) forms.     

Crystal Structures of [Ni(Phen)(i‐Bu2PS2)2] and [Ni(Phen)3](i‐Bu2PS2)2 Complexes and Interaction between Coordinated 1,10‐Phenanthroline Molecules

Single crystals of [Ni(Phen)(iBu₂PS₂)₂] (I) and [Ni(Phen)₃](iBu₂PS₂)₂ (III) compounds were grown, and their structures were determined by Xray diffraction analysis (CAD4 diffractometer, MoK radiation, 3336 F _hkl , R = 0.0373 for I and 2575 F _hkl for III). The crystals of complex I have a triclinic unit cell with the following parameters: a = 11.097(1) , b = 14.903(2) , c = 22.650(3); = 75.18(1)°, = 80.50(1)°, = 75.07(1)°, V = 3479.2(7)³, Z = 4, _calc = 1.255 g/cm³, and space group 1; the crystals of III have a monoclinic unit cell with the following parameters: a = 19.010(3), b = 15.481(1) , c = 17.940(3); = 97.58(1)°, V = 5233.5(12)³, Z = 4, _calc = 1.292 g/cm³, and space group C2/c. The structure of complex I is built from mononuclear molecules, and the structure of III, from [Ni(Phen)₃]²⁺ complex cations and i Bu₂PS₂ ^- outersphere anions. The NiN₂S₄ coordination polyhedra in the structure of I and NiN₆ in the structure of III are distorted octahedra. Based on structural data, the interaction between the coordinated Phen molecules of complexes I, [Ni(Phen)₂(iBu₂PS₂)](iBu₂PS₂) (II), and III is considered, as well as the packing modes of these complexes.     

Synthesis of β‐Chlorinated Macrocyclic [Au(C14H20N4Cl2)]X (X = AuCl2, ClO4, AuCl4) Gold(III) Complexes. Crystal and Molecular Structures of [Au(C14H20N4Cl2)]ClO4

A squareplanar [AuL₂]⁺ gold(III) complex [L₂ = 6.13dichloro5,7,12,14tetramethyl1,4,8,11tetraaza4,6,11,13tetraenato(2-)] containing two chlorine atoms in the position of the ligand hexacyclic ring was first synthesized by the reaction of the [AuL₁]⁺ tetraiminate complex [L₁ = 5,7,12,14tetramethyl1,4,8,11tetraaza4,6,11,13tetraenato(2-)] with HAuCl₄ in an acetone – DMFA solution. The complex was isolated in the form of dichloroaurite (I), perchlorate (II), and tetrachloroaurate (III). Compounds I–III were studied by elemental and Xray diffraction analyses and IR and NMR spectroscopies. Single crystals of [AuL₂]ClO₄ were obtained, and the crystal structure of this compound was determined from Xray diffraction patterns. The crystals are monoclinic: a = 10.147(2), b = 7.260(1), c = 12.519(2), = 96.70(1)°, V = 915.9(3)³, Z = 2, space group P2/c, d_calc = 2.218, d_meas = 2.209 g/cm³ The crystal structure is built of nearly planar [Au(C₁₄H₂₀N₄Cl₂)]⁺ cations and [ClO₄]^- anions. Introduction of chlorine atoms into the positions of the hexacyclic rings of the tetraazamacrocycle hardly changes the lengths of the delocalized C N and C C bonds.     

Crystal and Molecular Structure of 2‐nitro‐1‐ureidoguanidine

An Xray structural investigation of 2nitro1ureidoguanidine has been carried out. The crystals are monoclinic: a = 4.4690(2), b = 15.566(1), c = 9.4131(7), = 94.896(5)°, V = 652.4(3)> ³, space group P2₁/n, Z = 4, _calc = 1.650 g/cm³. The molecule consists of two planar fragments: carbamide and nitroguanidine. The geometrical characteristics of the molecule are analyzed. The system of intra and intermolecular hydrogen bonds in the crystal is considered.     

Influence of F and CF3 Groups at the C=C Double Bond on the Structure and Properties of Olefinic‐Series Compounds in the Gas Phase: an ab initio MP2 Study

Ab initio calculations of gasphase fluoroolefins with F or CF₃ groups as substituents at the C=C double bond were performed using secondorder Möller–Plesset perturbation theory (MP2) with the 6–31G^* and augccpVDZ basis sets and full geometry optimization. Geometrical parameters, singleelectron energies, electrondensity distributions, dipole moments, polarizabilities, and hyperpolarizabilities were computed. Variations in the electronic structure of fluoroolefins were analyzed and compared with variations in their physicochemical properties and reactivity.     

Solution properties and mesophase formation of 4‐phenyl‐benzoylcellulose

Cellulose samples were derivatized in dimethylacetamide/LiCl (DMAc/LiCl) to give 4phenylbenzoylcelluloses (PBCs). The process is quantitative and leads to an highly substituted product, as verified by elemental analysis, IR and ¹³CNMR spectroscopy. PBC samples were characterized by viscometric and light scattering measurements in DMAc. The persistance length q is used to evaluate the theoretical critical volume fraction for mesophase formation (v _th, which has been found higher than the experimental critical one (v _exp)     

Crystal and Molecular Structure of Monoammonium Salt of 5‐nitroaminotetrazole

Xray structural investigation of the monoammonium salt of 5nitroaminotetrazole was performed. The crystals are orthorhombic: a = 10.077(1), b = 17.009(1), c = 6.6472(6), V = 1139.33(17)³, space group Pbca, Z =8, _calc = 1.715 g/cm³. Monodeprotonation of 5nitroaminotetrazole during formation of the salt occurs at the N(4) nitrogen atom of the heterocycle. The anion has an almost flat structure; the bond lengths suggest delocalization of electron density in the molecule. The negative charge is distributed among three nitrogen atoms and two oxygen atoms of the anion. Changes in the geometrical parameters of 5nitroaminotetrazole on monodeprotonation are considered.     

A new strategy for alkane oxidation with O2 using N‐hydroxyphthalimide (NHPI) as a radical catalyst

A practical catalytic method to convert alkanes into the corresponding oxygencontaining compounds with O₂ under mild conditions using Nhydroxyphthalimide (NHPI) in the presence or absence of a transition metal was developed. Thus, cyclohexane was successfully converted into adipic acid in good conversion and selectivity by a combined catalytic system consisting of NHPI and Mn(acac)₂. Lower alkane such as isobutane was converted into tbutyl alcohol (83%) under 10 atm of air by NHPICo(OAc)₂ system. Alkylbenzene such as toluene was oxidized to benzoic acid in high yield (81%) under normal temperature and pressure of dioxygen in the presence of a catalytic amount of NHPI and Co(OAc)₂. ESR measurements showed that phthalimideNoxyl generated from NHPI under dioxygen atmosphere is a key species in this oxidation and functions as a radical catalyst.     

Crystal Structure of Dehydrated Wairakite

Singlecrystal Xray analysis was employed to study dehydrated wairakite Ca_0.97Na_0.06K_0.03×[Al_1.95Si_4.04O₁₂] with the following parameters: a = 18.260(4) , b = 18.284(4) , c = 13.432(3) , = 90.28(3)°, V = 4989(3) ³, Z = 16, space group B2₁/d. A comparison was carried out with the structure of the hightemperature (600°) phase, space group I4₁/acd. The coordination of the Ca cations increased from 4 to 4 + 1. Additional ligands were acquired from the fourmember ring of the framework upon its deformation and a pairwise countershift of the cations along the c axis. This resulted in a pseudotetragonal unit cell with a doubled volume and lowered symmetry.     

Crystal Structure of the Octahedral Cs4[Re6S8Br6] · 2H2O Cluster Complex

The octahedral Cs₄[Re₆S₈Br₆] cluster complex was obtained by the hightemperature (850°) reaction of stoichiometric amounts of elemental substances (metallic rhenium, sulfur, bromine) in molten CsBr. Crystal hydrate of Cs₄[Re₆S₈Br₆]· 2H₂O composition was isolated by recrystallization from an aqueous HBr solution. The crystal structure of the hydrate was determined by means of singlecrystal Xray structural analysis. The compound crystallizes in the hexagonal system with space group P6₃/mcm and unit cell parameters a = 9.762(1), c = 18.763(2), V_cell = 1548.5(3)³, Z = 2, d _calc = 5.192 g/cm³.     

Non‐linear transformations for rapid and efficient evaluation of multicenter bielectronic integrals over B functions

This work presents an extremely efficient nonlinear transformation based on a certain Hankel type transform, originally due to A. Sidi. The approach is applied to evaluating Coulomb integrals in the molecular context. These integrals are bielectronic one, two, three and fourcenter terms arising from the interactions of electron distributions over a Slater type orbital basis. They occur in many millions of terms, even for small molecules, and require rapid and accurate evaluation. The present work shows how we can reduce the order of the linear differential equation required to be satisfied by the integrand considerably. Calculation times as short as 10^-2 ms were obtained for fourcenter terms (the least favorable case) on an IBM RS6000340 workstation. This method represents a considerable advance on previous work on Coulomb integrals.     

Two‐dimensional step‐scan FTIR: a tool to unravel the OH‐valency‐range of the spectrum of Cellulose I

This article presents the results of the first application of dynamic mechanical analysis (DMA) coupled with 2D stepscan Fourier transform infrared (FTIR) spectroscopy, to cellulose. It is demonstrated that the broad hydroxyl infrared absorption band between 3700 and 3000cm^–1 in the cellulose infrared spectra could be separated into distinct bands by this dynamic rheooptical investigation using FTIRspectroscopy as detecting system. The responses of the OHgroups to an external perturbation were recorded as inphase and outofphase spectra. The cross correlation of these spectra gave the 2D synchronous and asynchronous plots, which showed clearly separated bands in the OHvibration range and the relation of the OHgroups to each other. It is demonstrated that it is possible to establish relations between the OHbands and the cellulose structure.     

Carboxymethylation of cellulose in unconventional media

Carboxymethylation of cellulose in the new and highly efficient aqueous solvent Ni(tren)(OH)₂, [tren=tris(2aminoethyl)amine] and in melts of LiClO₄· 3H₂O or NmethylmorpholineNoxide (NMMNO), which is now widely applied for cellulose fibre production, was investigated. In case of Ni(tren)(OH)₂, a totally homogeneous carboxymethylation of cellulose with sodium monochloroacetate, in the presence of an aqueous NaOH solution is possible for the first time. Structure analysis by means of HPLC and ¹ HNMR after chain degradation showed results comparable with findings for CMC obtained by the heterogeneous slurry process, that is, a statistic distribution of substituents along the polymer chain and functionalisation of the hydroxyl groups in the order C6 C2 > C3. The etherification of cellulose in a melt of LiClO₄· 3H₂O, a new type of cellulose solvent, was shown to be possible and gave products of a statistic functionalisation pattern as well. In contrast, carboxymethylation starting from solutions of cellulose in NMMNO initiated with solid NaOH particles yields polymers with a nonstatistic distribution of functional groups along the chain, as observed for cellulose ethers prepared in reactive microstrctures starting from solutions of cellulose intermediates in dimethyl sulfoxide as well as of unmodified cellulose dissolved in N,Ndimethyl acetamide/LiCl.     

Hydrothermal Synthesis and Structure of Organically Templated One‐Dimensional and Three‐Dimensional Iron Fluorophosphate

Two new openframework iron fluorophosphates, [C₄N₂H₁₂]_0.5[FeF(HPO₄)(H₂PO₄)] (I) [C₄N₂H₁₂][Fe₄F₂(H₂O)₄(PO₄)₄] · 0.5H₂O (II), were synthesized hydrothermally using piperazine as a templating agent. The structures were determined by singlecrystal Xray diffraction. Compound I crystallizes in the orthorhombic space group Pbca, a = 7.2126(2) , b = 14.2071(4) , c = 17.1338(2) , Z = 8. The structure is composed of infinite anionic chains of [FeF(HPO₄)(H₂PO₄)]^- _n built by transfluorine sharing FeF₂O₄ octahedra. These chains are similar to those found in tancoitetype minerals. Compound II crystallizes in the monoclinic space group P2₁/n, a = 9.9045(3) , b = 12.3011(3) , c = 17.3220(4) , = 103.7010(10)°, Z = 4. The structure of compound II has a threedimensional (3D) architecture with an eightmembered channel along the b axis, in which protonated piperazine molecules reside. The complex framework is built from two types of secondary building unit (SBU): one hexamer [Fe₃F₂(H₂O)₂(PO₄)₃$] (SBU6), and one dimer [FeO₄(H₂O)₂PO₄] (SBU2). The vertex sharing between these SBUs create the 3D structure.     

35Cl NQR Studies of the Geometry of Aromatic Imines

The preferred conformation of solidphase R4benzylidene3,4dichloroaniline molecules has been established by nuclear quadrupole resonance (NQR) combined with quantum chemical calculations. The conformational effect of substitutes reported previously is proved. The rotation angle of the plane of the aniline ring with respect to the plane of the azomethine bond is given.