Concerning restricted rotations in pyridinyl anisoles and pyridinyl phenols bearing saturated handles,and their solid state structures

The variable-temperature («dynamic») NMR measurements of series of pyridinyl anisoles and pyridinyl phenols each of them bearing ortho, ortho′ handles of various lengths at oxygenated ring lead to the following results: (i) at room temperature, a restricted rotation around the intercyclic bond of pyridinyl anisoles and pyridinyl phenol bearing short handles formed by 9–10 atoms is underscored, (ii) all handles at the former derivatives are blocked on one side of the oxygenated ring face, and (iii) handles of 11–12 atoms long at phenol rings are able to move freely. The solid-state packing indicates that all saturated chains are substantially perpendicular to the oxygenated ring.     

Thermomorphic metal scavengers: A synthetic and multinuclear NMR study of highly fluorinated ketones and their application in heavy metal removal

The preparation of a ketone with two long chain perfluoroalkyl groups is reported via the coupling reaction of a perfluorinated alkylzinc reagent and a perfluoro-acid chloride. This ketone has been investigated in the heterogeneous removal of heavy metals M²⁺ (M = Sn, Cd, Pb, Hg) and As⁵⁺ from aqueous solutions and removal of these metals from organic solvents using the unique thermomorphic properties of the fluorous ketone. In addition, a comprehensive ¹³C NMR study of one of the intermediates in the synthesis, 2H,2H,3H,3H-perfluoronanoic acid, has allowed the determination of all ¹J_C-F and ²J_C-F coupling constants. Also reported is the crystal structure of the acid CF₃(CF₂)₅CH₂CH₂CO₂H.     

Crystal structures of bile salts: Sodium taurocholate

Crystals of sodium taurocholate (NaC₂₆H₄₄NO₇S · 2.5 H₂O) belonging to the triclinic space groupP1 have unit cell parametersa = 12.731 (2),b = 16.104 (2),c = 7.628 (1) A, =83.40 (1), = 101.20 (1), = 105.35 (1)°, and two molecules in the asymmetric unit. The refinement, carried out on 4424 observed reflections, gaveR = 0.059 andR _w = 0.066. The packing is characterized by bilayers, formed by antiparallel monolayers and with nonpolar outermost surfaces, held together by van der Waals interactions. Inside the bilayers there are channels, lined with polar groups, and filled by sodium ions and water molecules. A structural unit has been identified that could provide a reasonable model for the micellar aggregates of this bile salt. Supplementary Data relevant to this article have been deposited with the British Library under the reference number SUP 82125 (38 pages).     

A possible helical model for sodium glycocholate micellar aggregates

Sodium glycocholate crystallizes in the tetragonal space group14 witha =b = 27.793(4),c = 7.937(1) Å andZ = 8. Refinement based on 2290 observed reflections led to a conventionalR = 0.10. The bile salt molecules are arranged in a helix with 2₁ symmetry stabilized mainly by polar interactions. Four helices are held together by hydrogen bonds involving water molecules, giving rise to hydrophilic channels, with a small cross section, which can include water molecules. The packing of these tetramers form hydrophobic channels containing some disordered acetone and water molecules. The helices will be checked as a model for the micellar aggregates of this important conjugated bile salt, following the same strategy successfully applied to sodium deoxycholate. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82107 (20 pages).     

Synthesis and characterisation of tetra-tetrazole macrocycles

The syntheses of tetra-tetrazole macrocycles, containing two bis-tetrazole units linked by a variety of alkyl-chain lengths from four to eight carbons, are described. The crystal structures of three of these derivatives are reported, and the molecular conformation in the solid state is compared to that of the previously reported tetra-tetrazole macrocycle and to other bis- and tris(tetrazole)benzene structures. The macrocycle conformation is influenced by the length of the alkyl-chain linker, the relative orientation of the tetrazole rings on the benzene ring and by intermolecular interactions. In the macrocycles based on 1,2-bis(tetrazole)benzene, the adjacent tetrazole rings on the benzene ring are prevented from becoming co-planar on intramolecular (steric) grounds. In the 1,3- and 1,4-bis(tetrazole)benzene derivatives, there is no such impediment, and a co-planar arrangement is observed where intra- and/or intermolecular stacking interactions exist. Deviations from co-planarity are associated with optimisation of intermolecular interactions between the tetrazole rings and adjacent alkyl chains. In the macrocycle based on 1,4-bis(tetrazole)benzene with four-carbon linkers, an intramolecular stacking interaction exists, which precludes the presence of any cavity. In the macrocycle based on 1,3-bis(tetrazole)benzene with six-carbon linkers, a cavity of 10.8×9.4 Å is observed for each molecule in the solid state, although the packing of adjacent molecules is such that there are no extended channels running through the crystal.     

Extraction and Absolute Crystal Structure of Stachyose

The title compound stachyose(C24H42O21),a biologicaly active tetrasaccharide,was characterized by X-ray diffraction analysis.It crystallizes in the orthorhombic system,space group P21212 with C24H42O21,a = 23.8760(3),b = 12.71028(12),c = 10.81279(11) ,V = 3281.36(6) 3,Z = 4,Dc = 1.511 g/cm3,Mr = 746.58,F(000) = 1576,and μ = 1.230 mm-1.The final R = 0.0666 and wR = 0.1797 for 6298 observed reflections(I 2σ(I)).The molecular crystal structure of stachyose shows absolute stereochemistry of β-D-fructofuranosyl α-D-galactopyranosyl-(1→6)-α-D-galactopyranosyl-(1→6)-α-D-glucopyranoside.The molecule is composed of two α-D-galactoses,one α-D-glucose,and one β-D-fructose and sequentially linked as α-Gal(1→6) α-Gal(1→6) α-Glc(1→2) β-Fru.The title compound is stacked into a 3D layer structure through hydrogen bonds.NMR spectra data are also assigned.In the crystal packing,X-ray analysis indicates that there are two intramolecular and eleven intermolecular hydrogen bonds in this compound.     

Extraction and Crystal Structure of β-Sitosterol

The title compound β-sitosterol(C29H50O), an active phytosterol in many medicinal and edible plants, was characterized by X-ray diffraction analysis and extensive nuclear magnetic resonance(NMR) data. It crystallizes in monoclinic system, space group P21 with C29H50O·1/2H2O, a = 9.4226(7), b = 7.4824(9), c = 36.889(3) , V = 2597.0(4) 3, Z = 4, Dx = 1.084 g/cm3, Mr = 423.70, F(000) = 948, and μ = 0.064 mm-1. The final R = 0.0886 and wR = 0.2234 for 10157 observed reflections(I 2σ(I)). The molecular crystal structure of β-sitosterol shows relative stereochemistry of 24R-ethylcholest-5-en-3β-ol. The molecule is composed of one steroid nucleus(3 six-membered rings and 1 five-membered ring) and one sidechain of 10 carbons. There are two C29H50O molecules and one H2O molecule in a symmetrical unit, and the title compound is stacked into a special laminated structure through hydrogen bonds and van der Waal forces. The special laminated structure was first reported.     

H?TiO oder TiB2?? – eine Korrektur

H? TiO or TiB₂? – A Correction Reinvestigations of “H? TiO” single crystals and the comparison with measurements of TiB₂ crystals have shown that “H? TiO” in fact is titanium diboride.     

Tryptophan-derived peptides. 1: Crystal structure and solution conformation of Boc-Gly-Trp-Ala-OtBu

The solid-state structure of Boc-Gly-Trp-Ala-OBu^t was determined by single-crystal X-ray diffraction analysis. The tripeptide gave crystals belonging to the orthorhombic systemP2₁2₁2₁ and at 122.0(5) K:a=11.0663(12),b=14.107(2),c=17.275(2) Å,V=2697.0(5) ųZ=4,R(F)=0.0259, andR _w(F)=0.0695. The peptide adopts a type-I-turn in the solid state with a single, rather weak, intramolecular hydrogen bond between the Boc-CO and Ala-NH groups (NO 3.082(1) Å, <NHO 167(1)°). The conformation of the Boc-Gly-Trp-Ala-OBu^t peptide has also been studied by¹H NMR spectroscopy. The solvent and temperature dependencies of NH chemical shifts suggests that this hydrogen bond is broken and that all amide protons are solvent exposed in CDCl₃ and (CD₃)₂SO.     

Synthesis,spectral, thermal and BVS investigations on ZnS4N^N/N coordination environment: Single crystal X-ray structures of bis(dibenzyldithiocarbamato)(N^N)Zinc(II) complexes (N^N = 1,10-phenanthroline,tetramethylethylenediamine and 4,4′-bipyridine)

The current paper describes the synthesis and spectral investigations on the adducts of [Zn(dbzdtc)₂] (1) with 1,10-phen (2), tmed (3), 2,2′-bipy (4) and 4,4′-bipy (5) (where, dbzdtc = dibenzyldithiocarbamate anion, 1,10-phen = 1,10-phenanthroline, tmed = tetramethylethylenediamine, 2,2′-bipy = 2,2′-bipyridine, 4,4′-bipy = 4,4′-bipyridne) and single crystal X-ray structures of [Zn(dbzdtc)₂(1,10-phen)] (2) and [Zn(dbzdtc)₂(tmed)] (3) and [Zn(dbzdtc)₂(4,4′-bipy)] (5). ¹H and ¹³C NMR spectra of 1,10-phen, tmed, 2,2′-bipy and 4,4′-bipy adducts were recorded. ¹H NMR spectra of the complexes show the drift of electrons from the nitrogen of the substituents forcing a high electron density towards sulfur via the thioureide π-system. In the ¹³C NMR spectra, the most important thioureide (N¹³CS₂) carbon signals are observed in the region: 206–210 ppm. Fluorescence spectra of complexes (2) and (4) show intense fluorescence due to the presence of rigid conjugate systems such as 1,10-phenanthroline and 2,2′-bipyridine. The observed fluorescence maxima for complexes with an MS₄N₂ chromophore in the visible region are assigned to the metal-to-ligand charge transfer (MLCT) processes. Single crystal X-ray structural analysis of (2) and (3) showed that the zinc atom is in a distorted octahedral environment. Bond Valence Sum was found to be equivalent to 1.865 for (2), 1.681 for (3) supporting the correctness of the determined structure. BVS of (3) deviates from the formal oxidation number of zinc due to the non-aromatic, sterically hindering tetramethyl bonding end of tmed. Thermal studies on the compounds show the formation of Zn(NCS)₂ as an intermediate during the decay.     

NMR and fluorescence spectral studies on bisdithiocarbamates of divalent Zn,Cd and their nitrogenous adducts: Single crystal X-ray structure of (1,10-phenanthroline)bis(4-methylpiperazinecarbodithioato) zinc(II)

The current paper describes the synthesis and characterization of the following adducts: [Zn(4-mpzdtc)₂(1,10-phen)] · H₂O (1), [Zn(4-mpzdtc)₂(2,2′-bipy)] (2), [Cd(4-mpzdtc)₂(1,10-phen)] (3), [Cd(4-mpzdtc)₂(2,2′-bipy)] (4), [Zn(padtc)₂(1,10-phen)] (5) and [Cd(padtc)₂(1,10-phen)] (6) (where, 4-mpzdtc = 4-methylpiperazinecarbodithioate anion, padtc = N,N′-(iminodiethylene)bisphthalimide dithiocarbamate anion, 1,10-phen = 1,10-phenanthroline and 2,2′-bipy = 2,2′-bipyridine). All the synthesized complexes were characterized by UV–Vis, IR, NMR, (¹H and ¹³C) and fluorescence spectra. A single crystal X-ray structural analysis was carried out for complex 1. IR spectra of the complexes show the contribution of the thioureide form to the structures. The observed deshielding of the α-protons for 1–6 in the ¹H NMR spectra is attributed to the drift of electrons from the nitrogen of the NR₂ groups, forcing a high electron density towards sulfur via the thioureide π-system. In the ¹³C NMR spectra, the most important thioureide (N¹³CS₂) carbon signals are observed in the region 206–208 ppm. Fluorescence spectra of complexes 5 and 6 show intense fluorescence due to the presence of rigid conjugated systems such as phthalimide and 1,10-phenanthroline. The observed fluorescence maxima for complexes with a MS₄N₂ chromophore in the visible region are assigned to the metal-to-ligand charge transfer (MLCT) processes. Single crystal X-ray structural analysis of 1 showed that the zinc atom is in a distorted octahedral environment with a MS₄N₂ chromophore. VBS equivalent to 1.81 supports the correctness of the determined structure. The piperazine ring in the dithiocarbamate fragment is in the normal chair conformation.     

A six-coordinate aryl-germanium complex formed by the Kläui ligand

PhGeCl₃ reacts with Na{[OP(OEt)₂]₃CoCp} to give the six-coordinate complex PhCl₂Ge{[OP(OEt)₂]₃CoCp}, characterised spectroscopically and by an X-ray crystal structure determination which showed a firmly-attached tridentate ligand [Ge-O 1.973(2) Å].     

Eine neue Hochtemperaturform von TiO: H?TiO

A New High Temperature Form of TiO: H? TiO Single crystals of a high temperature form of TiO (H? TiO) were prepared above 3 000°C by CO₂-LASER technique. They crystallize with a hitherto unobserved crystal structure of oxides with titanium in the oxidation state two, isotypic to tungsten carbide with Ti²⁺ in a trigonal prismatic surrounding by oxygen. Space group D–P6 m2, a = 3.0310, c = 3.2377 Å, Z = 1.     

Fluoride Ion Receptors: A Comparison of a Polyammonium Monocycle Versus its Bicyclic Corollary

Abstract

Two polyammonium macrocyclic receptors, the monocyclic 3,6,9,17,20,23-hexaazatricyclo [23.3.1.1^11,15]triaconta-1(29), 11,13,15(30),25,27-hexaene (L¹) and its bicyclic analog 1,4,12,15,18,26,31,39-octaazapentacyclo[13.13.13.1^6,10. 1^20,24.1^33,37]-tetratetraconta-6,7,9,20(43),21,23,33(42),34,36-nonaene (L²), have been synthesized as their hexatosylate salts. The propensity for binding fluoride ion was examined using both NMR and potentiometric techniques. The fluoride salts of both receptors have been characterized by X-ray crystallographic methods. For the monocycle, the complex crystallized as the mixed fluoride-bifluoride salt, [H₆L¹]⁶⁺ ·4F^? ·2FHF^? ·4H₂O, and the bicycle crystallized as a complex salt, [H₆L²]⁶⁺ ·F^? ·2FHF^? ·1.5SiF₆ ^2? ·7H₂O.     

First X-ray structural characterisation of host-guest interactions in tetra-tetrazole macrocycles

The syntheses of tetra-tetrazole macrocycles, containing two 1,3-bis(tetrazole)benzene units linked by a variety of n-alkyl (n=3, 5, 7 or 9 carbon atoms) chain lengths, are described. The crystal structures of two 1,3-bis(tetrazole)benzenes containing pendant bromoalkyl chains (n=3 or 5) are reported. A tetra-tetrazole macrocycle has also been structurally characterised and contains an unexpected ‘host-guest’ interaction through binding of a chloroform solvent molecule. The resulting deviation of the macrocycle from planarity results from a combination of the ‘host-guest’ interaction and strong intermolecular interactions between adjacent tetrazole and phenylene rings.     

The chemistry of trityl isoselenocyanate revisited: A preparative and structural investigation

The reaction of trityl chloride with KSeCN gives trityl isoselenocyanate which was structurally characterised by X-ray diffraction. Trityl isoselenocyanate reacts with hydrazine to give trityl selenosemicarbazide and with primary amines to give selenourea derivatives. However, with secondary amines mixtures of selenoureas and substitution products are formed. Trityl selenosemicarbazide undergoes a condensation reaction with salicylaldehyde to give the corresponding trityl selenosemicarbazone. In the case of 2-pyridinecarboxaldehyde, the analogous selenosemicarbazone cannot be isolated, instead a small quantity of the diselenide was isolated from the reaction mixture. The compounds prepared here were fully characterised spectroscopically and several also by X-ray diffraction.     

A convenient synthesis of some symmetrical and unsymmetrical diarylmethyl sulfur and selenium compounds: X-ray crystal structure of diphenylmethylseleno-2-propene and bis[p-chlorophenyl(phenyl)methyl] diselenide

A number of novel and synthetically important symmetrical and unsymmetrical diarylmethyl sulfur and selenium compounds have been synthesized and characterized with the help of elemental analysis and various spectroscopic techniques. The methodology employs sodium borohydride in ethanol-DMF for E-E bond cleavage (where E = S, Se) at room temperature and gives satisfactory yield of the titled compounds. Molecular structure of bis[p-chlorophenyl(phenyl)methyl] diselenide (3) and diphenylmethylseleno-2-propene 7 has been established with the help of single crystal X-ray analysis. The compound (3) is triclinic and crystallizes into space group, whereas the compound 7 is monoclinic with P2₁/C space group.     

Ammonium hexafluorosilicate salts

The preparation and characterization of the ammonium hexafluorosilicate salts, 2[R]⁺ [SiF₆]²⁻ (where R=piperidinium (2), methylammonium (3), quinolinium (4), acridinium (5), 2,2,6,6-tetramethylpiperidinium (6), and propylammonium (7)) is described.The salts were prepared from the reaction of the corresponding alkylammonium fluoride with silica gel. The compounds were characterized by NMR, IR, mass spectrometry and in the case of 1 (piperidinium fluoride), 2-4 by X-ray crystallography. Compounds 1-3 crystallize in the orthorhombic crystal system (space groups Iba2, Fdd2, and Pnnm, respectively), with Z=8, 14, and 4, respectively. Compound 4 crystallizes in the triclinic space group P-1, with Z=2. Compounds 1-4 exhibit hydrogen bonding.     

Methanol als Ligand in Natriumphenolat: Darstellung und Struktur von [Na(CH3OH)4][OC6H5]

Methanol as a Ligand in Sodium Phenoxide: The Synthesis and Crystal Structure of [Na(CH₃OH)₄][OC₆H₅] By the reaction of sodium and phenol in N-methyl-?-caprolactam (NMC) sodium phenoxide has been yielded, which forms a complex with the furthermore obtained methanol of [Na(CH₃OH)₄][OC₆H₅]. The single crystals crystallize triclinic, space group P1 , with the lattice constants a = 6.613(3) Å, b = 10.537(4) Å, c = 10.656(4) Å, α = 108.27(2)°, β = 98.21(2) and γ = 95.26(2)°. Sodium is coordinated by six oxygen atoms of methanol in the form of an octahedron. These coordination polyhedrons are connected by sharing edges forming chain, whereas, the oxygen of phenoxide is not involved in the coordination of sodium. Although it is attached to the chain by hydrogen bonding.     

THE CRYSTAL AND MOLECULAR STRUCTURE OF A FURAN-2-CARBOXYLATE HETEROBIMETALLIC COMPLEX [Zn(H2O)6]2+[Zn8Na2(C5H3O3)18(OH)2]2-

Abstract

The crystals of a zinc-sodium complex with furan-2-carboxylate (FCA) as a ligand, n[Zn(H₂O)₆]²⁺[Zn₈Na₂(FCA)₁₈(OH]₂]^2- _n , contain hexahydrated zinc cations and polyanions in which four differently coordinated zinc(II) cations are bridged by bidentate and monodentate (FCA) ligands. In addition, a number of carboxylate and furan ring oxygen atoms are coordinated to sodium(I) atoms which constitute the backbone of the polyanion. [Zn(H₂O)₆]²⁺ cations are located in cavities formed by adjacent polyanions and interact with them via a system of hydrogen bonds. The resulting molecular layers are stacked in the crystal along the [100] direction.