bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Sesquiterpene Lactone Sulfate from Reichardia gaditana (Asteraceae)
Authors: Zidorn Christian , Ellmerer Ernst-Peter , Heller Werner , Greil Richard , Guggenberger Manuela , Ongania Karl-Hans , Stuppner Hermann
Published: February 2015

The new sesquiterpenoid 8-deoxy-15-(3′-hydroxy-2′-methyl-propanoyl)-lactucin 3′-sulfate (1) was isolated from the methanolic extract of roots of Reichardia gaditana L. The compound was isolated by silica gel column chromatography (CC) and repeated Sephadex LH-20 CC. Structure elucidation was accomplished by high-resolution mass spectrometry and by 1D- and 2D-NMR spectroscopy. The chemosystematic significance of the new compound is discussed in the context of sesquiterpenoids from other members of the Lactuceae tribe of the Asteraceae family.
Anthranoyl-substituted Norditerpene Alkaloids from Aconitum vulparia Rchb. and Their Cytotoxic Activities
Authors: Csupor Dezső , Forgo Peter , Zupkóc István , Szabód Pál , Hohmann Judit
Published: February 2015

Extensive chromatographic purification of the alkaloid fraction of Aconitum vulparia Rchb. led to the isolation of a new norditerpene alkaloid, vulparine (1), besides the known compounds septentriodine (2), finetiadine (3), anthranoyllycoctonine (4), N-methyl-N-deethyllycoctonine (5) and delectinine (6). The structure of the new compound was determined by means of HRMS, 1D and 2D NMR spectroscopy. Detailed NMR studies, including 1H-1H COSY, NOESY, HSQC and HMBC experiments, resulted in complete and unambiguous 1H chemical shift assignments for 2 and 6, and revision of some 13C NMR data. Compounds 1 - 4 were evaluated for their cytotoxic activities, and 1, 3 and 4 were found to exhibit marginal cell growth inhibitory activity against breast adenocarcinoma (MCF-7) and cervix adenocarcinoma (HeLa) cells.
La6C2Br9: La-Tetraederdoppel mit endohedralen C4–-Ionen / La6C2Br9: La Bitetrahedral Clusters with Endohedral C4− Ions
Authors: Mattausch Hansjürgen , Hoch Constantin , Simon Arndt
Published: February 2015

Monophasic La6C2Br9 was prepared by heating a mixture of LaBr3, lanthanum metal and carbon in a molar ratio of 3 : 3 : 2 at 840 °C for 5 d. The crystal structure was investigated by X-ray single crystal diffraction (space group C2/c, a = 14.234(3), b = 10.858(2), c = 14.588(3) Å , β = 106.80(3) °). In the structure the La atoms form edge-sharing double tetrahedra. The La tetrahedra are centered by single carbon atoms. The yellow crystals of La6C2Br9 are transparent and electrically insulating.
Neue Arsenide mit ThCr2Si2- oder einer damit verwandten Struktur: Die Verbindungen ARh2As2 (A: Eu, Sr, Ba) und BaZn2As2 / New Arsenides with ThCr2Si2-type or Related Structures: The Compounds ARh2As2 (A: Eu, Sr, Ba) and BaZn2As2
Authors: Hellmann Andrea , Löhken Anke , Wurth Andreas , Mewis Albrecht
Published: February 2015

Four new arsenides of rhodium and zinc were prepared by heating mixtures of the elements at high temperatures (1000 - 1200 °C) and investigated by single crystal X-ray methods. EuRh2As2 (a = 4.067(1), c = 11.319(2) Å ) and BaRh2As2 (a = 4.053(1), c = 12.770(3) Å ) crystallize with the well-known ThCr2Si2-type (I4/mmm; Z = 2). Due to the rigid layers of RhAs4 tetrahedra, and to the atomic size of europium and barium, the As-As distances between the layers with values of 2.97 and 3.66 Å, respectively, are very long. SrRh2As2 is polymorphic and undergoes two phase transitions at about 190 and 282 °C. Main features of the three crystal structures are also layers of RhAs4 tetrahedra. At room temperature α-SrRh2As2 (a = 5.676(1), b = 6.178(2), c = 11.052(2) Å ) probably crystallizes with the BaNi2Si2-type (Cmcm; Z = 4), whereas β -SrRh2As2 (a = 5.760(3), b = 6.067(4), c = 11.264(5) A° , Fmmm, Z = 4) forms a new orthorhombically distorted variant of the ThCr2Si2-type. Single crystals grown in a flux of lead and quenched at high temperature show that the γ -phase (a = 4.112(1), c = 11.431(6) Å ) crystallizes with the ThCr2Si2-type. The same is true for the high temperature modification of BaZn2As2 (β -phase; a = 4.120(1), c = 13.578(1) Å ), whereas the already known α-BaZn2As2 forms the α-BaCu2S2-type (Pnma; Z = 4) consisting of a 3D-network of edge- and vertex-sharing ZnAs4 tetrahedra with Ba atoms in the voids of this network.
New Intermetallic Compounds RE4Co2Mg3 (RE = Pr, Gd, Tb, Dy) – Syntheses, Structure, and Chemical Bonding
Authors: Tuncel Selcan , Rodewald Ute Ch. , Matar Samir F. , Chevalier Bernard , Pöttgena Rainer
Published: February 2015

The magnesium compounds RE4Co2Mg3 (RE = Pr, Gd, Tb, Dy) were prepared by induction melting of the elements in sealed tantalum tubes. The samples were studied by powder X-ray diffraction. The structures of the gadolinium and of the terbium compound were refined from single crystal diffractometer data: Nd4Co2Mg3-type, P2/m, Z = 1, a = 754.0(4), b = 374.1(1), c = 822.5(3) pm, β = 109.65(4)°, wR2 = 0.0649, 730 F2 values for Gd4Co2Mg3 and a = 750.4(2), b = 372.86(6), c = 819.5(2) pm, β = 109.48(3)°, wR2 = 0.0398, 888 F2 values for Tb4Co2Mg3 with 30 variables each. The RE4Co2Mg3 structures are 3 : 1 intergrowth variants of distorted CsCl and AlB2 related slabs of compositions REMg and RECo2. Characteristic structural features (exemplary for Tb4Co2Mg3) are relatively short Tb-Co (271 pm), Co-Co (232 pm) and Mg-Mg (314 pm) distances. The latter are a geometrical constraint of the distortion of the REMg and RECo2 slabs. Chemical bonding analysis (ELF and ECOV data) for Gd4Co2Mg3 reveals strong Gd-Co bonding followed by Mg-Co, while the Mg-Mg interactions can be considered as weak. The Co-Co contacts are only weakly bonding. The bonding and antibonding states are almost filled.
Synthesis, Crystal Structure, and Spectral Characterization of Novel Three-dimensional Supramolecular Networks with One-dimensional Channels Based on Keggin-type Polyoxoanions and Mixed-Valence Dibenzotetrathiafulvalenes
Authors: Shi Dongmei , Chen  , Pang Haijun , Meng Fanxia , Sun Yu , Liu Kun , Liu Hongbo
Published: February 2015

A new organic/inorganic salt formed by mixed-valence dibenzotetrathiafulvalene (DBTTF) radical cations and the spherical Keggin-type polyoxometalate anions [H3BW12O40]2− was obtained by electrochemical oxidation of the donor in an acetonitrile and a 1,2-dichloroethane solution containing the polyanion. The compound has been characterized by X-ray diffraction, elemental analysis, EPR, IR and Raman spectroscopy. X-Ray diffraction experiments have revealed that the compound consists of heteropolyanions, water molecules and DBTTF radical cations. The organic radicals form trimers and dimers via π-π stacking; moreover, the polyoxoanions and the organic donors are also held together by hydrogen bonding interactions. In their packing arrangement, a three-dimensional supramolecular network with one-dimensional channels along the b axis is established with uncoordinated water molecules residing in the channels.
Synthesis and Unique Function of a Copper(II) Compound Possessing an Imidazole Moiety as an Anchor Group
Authors: Nishino Satoshi , Sutoh Yuichi , Togashi Takanari , Nishida Yuzo
Published: February 2015

A new copper(II) complex with a (bdpg-His) ligand was prepared and its structural properties were investigated both in crystalline and in solution states; (bdpg-His) = N,N-bis(2-pyridylmethyl) carnosine methylester. In the solid state, the complex has a dimeric structure, but in solution it partially dissociates into monomeric species, which have an imidazole moiety as an anchor group. This complex can prevent the precipitation of aggregated amyloid beta-peptide induced by zinc(II) ions, and affects the structure of the superoxide dismutase molecule, leading to the loss of the dimeric structure; these effects are probably due to the free imidazole group of the complex in solution.
Synthesis, Spectroscopic and X-Ray Structure Characterisation of Bis(tetramethylammonium) and Bis(tetra-n-butylammonium) Tetrathiomolybdates
Authors: Poisot Martha , Näther Christian , Bensch Wolfgang
Published: February 2015

The new tetraalkylammonium tetrathiomolybdates (Me4N)2[MoS4] (1) and (nBu4N)2[MoS4] (2) were prepared via a direct salt substitution using (NH4)2[MoS4] as starting material. Compound 1 crystallises in the non-centrosymmetric orthorhombic space group P212121 with a = 8.9233(4), b = 15.5210(9) and c = 37.255(3) Å. Compound 2 crystallises in the orthorhombic space group Fdd2 with a = 28.9142(18), b = 35.7811(10) and c = 15.6774(17) Å. The structures of both compounds consist of slightly distorted [MoS4]2− tetrahedra and tetraalkylammonium cations which are packed in different ways. Single crystals of (Et4N)2[MoS4] (3) were also investigated giving the lattice parameters a = 14.0346(7) and c = 12.5143(8) Å. A very strong disorder prevented a successful structure refinement and only the anion and one cation could be located. It is remarkable that the disorder of parts of the alkyl groups decreases with increasing chain length, in correlation with the IR and Raman vibrations of the [MoS4]2− tetrahedron showing a slight shift to lower energy with increasing alkyl chain length. The most prominent IR band of [MoS4]2− is broad but not split, indicating that the distortion of the tetrahedra is small.
Hydrogen Bonds in the Crystal Structure of Strontium Hydroxide Octahydrate Sr(OH)2 · 8H2O
Authors: Reuter Hans , Kamaha Shouassi , Zerzouf Otmane
Published: February 2015

Strontium hydroxide octahydrate Sr(OH)2 · 8 H2O crystallizes in the tetragonal space group P4/ncc with cell constants a = 9.017(1) and c = 11.603(1) Å . The crystal structure has been refined from 2656 diffractometer data up to 2ϑ = 60° to an R value of 0.0303. With the new diffraction data it was possible to localize the positions of all hydrogen atoms for the first time and to describe the hydrogen bonding scheme in detail. The Sr2+ ions are square antiprismatically coordinated by eight water molecules. These {Sr(H2O)8}2+ coordination polyhedra are linked with each other via hydrogen bonds in a way that linear columns parallel to the c axis result. The two hydroxyl anions of the asymmetric unit are linked by weak hydrogen bonds and are not coordinated to strontium atoms. Like the strontium atoms, they form linear chains parallel to the c axis. Both, {Sr(H2O)8}2+ columns and OH- chains, are interconnected through two types of additional hydrogen bonds.
Hypercoordinate Diorganosilanes Featuring an 〈ONO〉 Tridentate Ligand. A Surprising EquilibriumBetween Penta- and Tetracoordination
Authors: Wagler Jörg , Brendler Erica
Published: February 2015

The reaction of the tridentate ligand-precursor molecule 1, o-HO-p-MeO-C6H3-C(Ph)=N-(o-C6H4)-OH, with diorganodichlorosilanes Me2SiCl2, Ph2SiCl2 and PhAllSiCl2 yields pentacoordinate silicon complexes R,R′Si[o-O-p-MeO-C6H3-C(Ph)=N-(o-C6H4)-O] (2a′: R, R′ = Me; 2b: R, R′ = Ph; 2c: R = Ph, R′ = All). 2b and 2c have pentacoordinate silicon atoms in the solid state as well as in chloroform solution. Surprisingly, for 2a an isomer 2a′ with Si-tetracoordination is preferred in the solid state, while the Si-pentacoordinated isomer 2a may dominate in solution. The hypercoordinate allylsilane 2c with a C=X→Si moiety is stable in solution and does not undergo a 1,3-allyl-shift-reaction.
Oxidation cyclischer α-Aminoketone / Oxidation of Cyclic α-Aminoketones
Authors: Möhrle Hans , Rohn Christiane
Published: February 2015

The 1,2,3,4-tetrahydro-isoquinolin-4-one 4 reacts as an α-amino ketone with periodate to give various products, the major compound being 1-hydroxy-1,2-dihydro-3,4-isoquinolinedione 12. Upon stepwise oxidation with Hg(II)-EDTA the 4-hydroxyisoquinolinium ion 14 is detected as an intermediate and its further oxidation with periodate gives rise to an almost identical product spectrum. Because 12 represents a carbinolamide with an additional 4-carbonyl group, this type was examined first. Acid catalysis was used because the reactive species mostly are iminium ions. With cyclic 1,3- dicarbonyl compounds, 1-substituted derivatives 17a, b are formed.With linear species 1-substitution is also observed, but the tautomeric forms 19a - c are obtained. The stable enones 24a, b result from alkyl ketones by ready autoxidation of the primary products. Base catalysis induces a ring contraction of 12 to the hydroxycarboxylic acid 25. Reaction of 12 with aniline and phenylhydrazine yields the easily oxidizable 1-substitution products 28 and 31.
Studies With Enamines: Synthesis and Reactivity of 4-Nitrophenyl-1-piperidinostyrene. Synthesis of Pyridazine, Oxadiazole, 1,2,3-Triazole and 4-Aminopyrazole Derivatives
Authors: Abdallah Tayseer A. , Salaheldin Abdellatif M. , Radwan Naglaa F.
Published: February 2015

4-Nitrophenyl-1-piperidinostyrene (4) reacts with an aromatic diazonium salt to afford the arylhydrazonal 6. The latter condenses with active methylene compounds to yield pyridazine derivatives, and with hydroxylamine hydrochloride to produce oxadiazole and 1,2,3-triazole derivatives. Compound 12 was reacted with chloroacetonitrile to afford 4-aminopyrazoles 15.
New Eudesmane and Cadalane Sesquiterpenes from Parepigynum funingense
Authors: Hua Yan , Liu Hai-Yang , Zhou Jun , Chen Chang-Xiang
Published: February 2015

A new eudesmane sesquiterpene glycoside, named funingensin A (1), together with a novel cyclic ether based on the cadalane skeleton, named funingensin B (2), were isolated from the roots of Parepigynum funingense. Their structures were elucidated by spectroscopic methods, including oneand two-dimensional NMR (COSY, HMQC, HMBC and ROESY).
Biotransformation of Jatrophone by Aspergillus niger ATCC 16404
Authors: Pertino Mariano , Schmeda-Hirschmann Guillermo , Santos Leonardo S. , Rodríguez Jaime A. , Theoduloz Cristina
Published: February 2015

Biotransformation of the diterpene jatrophone (1) by Aspergillus niger ATCC 16404 afforded the new diterpene 9β -hydroxyisabellione (2). The compounds were characterized by spectroscopic analysis. The cytotoxicity of the compounds as IC50 values on AGS and lung fibroblasts was 2.4 and 2.8 μM for compound 1 and 53.1 and 260 μM for 2, respectively. Microbial transformation of 1 into compound 2 strongly reduced the cytotoxicity and enhanced the selectivity against AGS cells.
New Cycloartane-type Triterpenoids from Artocarpus nobilis
Authors: Zahid Shamsulhaq , Ata Athar , Samarasekera Radhika
Published: February 2015

Recent phytochemical studies on the ethanolic extract of Artocarpus nobilis, collected from Sri Lanka, have resulted in the isolation of two new cycloartane-type triterpenoids, artocarpuate A (1) and artocarpuate B (2). Structures of these new compounds were established with the aid of extensive NMR spectroscopic studies. Compounds 1 and 2 were found to exhibit weak acetylcholinesterase inhibitory activity.
The Synthesis of Copper(II) Salicylaldiminato Complexes and their Catalytic Activity in the Hydroxylation of Phenol
Authors: van Wyk Juanita L. , Mapolie Selwyn , Lennartson Anders , Håkansson Mikael , Jagner Susan
Published: February 2015

The synthesis of copper(II) salicylaldiminato complexes and their application in the catalytic hydroxylation of phenol is reported. Tetracoordinated copper complexes (Cu(Ln)2) were obtained by reacting the N-phenylsalicylaldimine ligands (HL1 -HL7) with copper acetate in a 2 : 1 mole ratio. The reaction of N-(2,6-diisopropyl)phenyl-3,5-di-tert-butylsalicylaldimine (HL7) with copper acetate in a 1 : 1 mole ratio afforded a dinuclear complex, which was not obtained with the other ligand systems. All complexes were characterized using FT-IR and elemental analysis. X-Ray crystal structures of complexes 2, 5 and 8 have also been obtained. The catalytic activity of these complexes was evaluated in the hydroxylation of phenol using oxygen and hydrogen peroxide as co-oxidants in aqueous media in the pH range 3 - 6. All complexes studied were found to be active for the hydroxylation process over the pH range studied with higher selectivity for catechol formation.
The Effect of Catalyst Isomerization on Polypropylene Properties
Authors: van Reenen Albert J. , Sultan Omar
Published: February 2015

Two C2-symmetric metallocene catalysts in solution were exposed to light, and the rac-meso conversion followed by NMR spectroscopy. Both exposed and unexposed catalyst solutions were used, in conjunction with a suitable cocatalyst, to polymerize propylene. The polymers were characterized with respect to their microstructure and fractionated according to crystallinity. The relationship between the catalyst isomerization and the polymer structure is illustrated. The effect of pre-activation of the catalyst before exposure to light was also studied and is reported on.
Angular Momentum in Chemistry
Authors: Boeyens Jan C.A.
Published: February 2015

Noting that current chemical theory is based almost exclusively on electronic energy and spin variables the equal importance of orbital angular momentum is explored in this paper. From its classical definition the angular momentum of electrons in an atom is shown to obey Laplace’s equation, which automatically leads to discrete values in terms of spherical harmonics. This analysis assumes a continuous distribution of electronic charge, which resembles a fluid at equilibrium. It serves to elucidate the success and failure of Bohr’s conjecture and the origin of wave-particle duality. Applied to atoms, minimization of orbital angular momentum leads to Hund’s rules. The orientation of angular momenta in lower-symmetry molecular environments follows from the well-known Jahn-Teller theorem.
New Synthetic Routes for 1-Benzyl-1,4,7,10-tetraazacyclododecane and 1,4,7,10-Tetraazacyclododecane-1-acetic Acid Ethyl Ester, Important Starting Materials for Metal-coded DOTA-Based Affinity Tags
Authors: Kohl Stephan W. , Kuse Katharina , Hummert Markus , Schumann Herbert , Mügge Clemens , Janek Katharina , Weißhoff Hardy
Published: February 2015

Two improved routes to synthesize 1-benzyl-1,4,7,10-tetraazacyclododecane (6) and 1,4,7,10- tetraazacyclododecane-1-acetic acid ethyl ester (11) are described as well as the synthesis of 1-{2-[4-(maleimido-N-propylacetamidobutyl)amino]-2-oxoethyl}-1,4,7,10-tetraazacyclododecane- 4,7,10-triacetic acid (17) and its Y, Ho, Tm, and Lu complexes. The 1H and 13C NMR spectra of the new compounds as well as the single crystal X-ray structure analyses of the intermediates 4-benzyl-1,7-bis(p-toluenesulfonyl)diethylenetriamine (3) and 1,4,7-tris(p-toluenesulfonyl)diethylenetriamine (7) are reported and discussed. The rare earth complexes of 17 have been characterized by 1H NMR spectroscopy and MALDI-TOF mass spectrometry.
Di-tungsten Bis-carbene Complexes Linked by Condensed Heteroaromatic Spacers
Authors: Landmana Marilé , Görls Helmar , Crause Chantelle , Nienaber Hubert , Olivier Andrew , Lotz Simon
Published: February 2015

The 2,7-dilithiated substrates of 3,6-dimethylthieno[3,2-b]thiophene, N,N′-dimethylpyrrolo[3,2- b]pyrrole and N-methylthieno[3,2-b]pyrrole were reacted with W(CO)6 to give, after subsequent alkylation with Et3OBF4, the ditungsten biscarbene complexes [(CO)5W{C(OEt)XXC(OEt)} W(CO)5] (XX = condensed heteroaromatic spacers). Sites of attack during the dilithiation of the condensed rings were studied and compared, and the yields of the desired ditungsten biscarbene complexes optimized by changing the reaction conditions according to the role of the heteroatoms in the rings. The crystallographic data of the three ditungsten biscarbene complexes are reported and their structural features compared. The methyl substituents on the condensed heteroaromatic rings play an important role in determining the molecular configurations.
A Novel Calix[4]arene-Dipyrrole Conjugate Designed for Complexation of Ion Pairs
Authors: Budka Jan , Curinova Petra , Gu Rong , Lhotak Pavel , Stibor Ivan , Schraml Jan , Dehaen Wim
Published: February 2015

A novel calixarene derivative with dipyrromethane moieties on the lower rim was prepared. NMR spectroscopy revealed a high selectivity towards sodium cations and the ability to bind ion pairs.
Introduction of Phosphine-Gold(I) Precursors into a Cys-modified Enkephalin Neuropeptide as Part of Solid Phase Peptide Synthesis
Authors: Caddy Judy , Hoffmanns Ulrich , Metzler-Nolte Nils
Published: February 2015

The synthesis and full characterization of a series of (triphenylphosphine)gold complexes with thiol-containing amino acids and peptides is reported. Boc-Cys-Au(PPh3) was prepared in solution by reaction of Boc-Cys-OH with (Ph3P)AuCl. The related Ac-Cys-Au(PPh3) and an Au derivative of the cysteine-modified neuropeptide enkephalin (Enk), [Cys]5-Au(PPh3)-Enk, were prepared on the resin, using the orthogonal trityl-protecting group on Cys. For comparison, the metal-free [Cys]5-Enk and an S-tert-butyl-protected [Cys]5-Enk were also prepared. Most noteworthy, gold complexation works best when carried out on the resin, and the gold thiolate survives cleavage from the resin under optimized conditions. The new conjugates were comprehensively characterized, including 1D and 2D NMR spectroscopy, and mass spectrometry. Along with characteristic changes in the 1H and 13C NMR spectra, 31P NMR spectra reveal a characteristic downfield shift of ca. 5 ppm upon complexation of the Au(PPh3)-fragment to Cys, which is also pertinent in the Au-labelled [Cys]5-Enk.
The Separation of Fe from Ga to Produce Ultrapure 67Ga
Authors: van der Meulen Nicholas P. , van der Walt Tjaart N.
Published: February 2015

The production of 67Ga at iThemba LABS is performed by the proton bombardment of a tandem natZn/natZn target. 67Ga is separated from the target material using a method based on target dissolution, in acidic media, and dual chromatographic methods on Amberchrom CG-161M. The result is a product with a high radionuclidic purity 67Ga having such a low Fe content in the final product that it may be used in the labelling of peptides.
Studies with 2-(Arylhydrazono)aldehydes: Synthesis and Chemical Reactivity of Mesoxalaldehyde 2-Arylhydrazones and of Ethyl 2-Arylhydrazono-3-oxopropionates
Authors: Makhseed Saad , Hassaneen Huwaida M. E. , Elnagdi Mohamed H.
Published: February 2015

The coupling reaction of 3-(dimethylamino)acrolein (2a) and ethyl 3-(dimethylamino)acrylate (2b) with arenediazonium chlorides afforded the 2-(arylhydrazono)aldehydes 1a - e. Compounds 1a, b reacted with hydroxylamine hydrochloride to yield the oximes 4a, b. The dioxime 5 was obtained from reaction of 1a with an excess of hydroxylamine hydrochloride. This dioxime afforded the 1,2,3-triazole carbonitrile 6 when treated with acetic anhydride, while α-hydrazono propionitrile 8 was obtained when 5 was treated with acetic acid. Compounds 1a - e could be utilized for the synthesis of a variety of pyrazoles and arylazolopyrimidines via reaction with hydrazines, haloketones and aminoazoles, respectively.
A New Antifeedant Withanolide from Jaborosa lanigera
Authors: Tettamanzi M. Cristina , Biurrun Fernando N. , Cirigliano Adriana M.
Published: February 2015

A new trechonolide-type withanolide, jaborosolactol, possessing a hemiketal ring system and a 5-membered lactol, has been isolated from the aerial parts of Jaborosa lanigera. The structure was elucidated based on spectroscopic and spectrometric methods (1D and 2D NMR, MS). The feeding deterrent activity of the compound against the Mediterranean fruit fly Ceratitis capitata was examined.
Glutathione S-Transferase, Acetylcholinesterase Inhibitory and Antibacterial Activities of Chemical Constituents of Barleria prionitis
Authors: Kosmulalage Kalhari S. , Zahid Shamsulhaq , Udenigwe Chibuike C. , Akhtar Sarfraz , Ata Athar , Samarasekera Radhika
Published: February 2015

Phytochemical studies on the ethanolic extract of Barleria prionitis of Sri Lankan origin have resulted in the isolation of a new compound, balarenone (1), along with three known compounds, pipataline (2), lupeol (3) and 13,14-seco-stigmasta-5,14-diene-3-α-ol (4). The structures of 1 - 4 were elucidated with the aid of extensive NMR spectroscopic studies. Compounds 1 - 4 showed moderate inhibitory activity against glutathione S-transferase (GST) and acetylcholinesterase (AChE). Compounds 1, 2 and 4 also exhibited antibacterial activity against Bacillus cereus and Pseudomonas aeruginosa (25 μg/disk). Three different derivatives of compound (2), 7,8-epoxypipataline (5), 8- amino-7-hydroxypipataline (6) and 7,8-dibromopipataline (7) were synthesized to evaluate them for GST and AChE inhibitory activities. Household microwave radiations were used to synthesize compound (6). Among all tested compounds, 8-amino-7-hydroxypipataline (6) exhibited a significant AChE inhibitory activity with an IC50 value of 36.8 μM.
Microbial Hydroxylation of Hydroxyprogesterones and α-Glucosidase Inhibition Activity of Their Metabolites
Authors: Choudhary Muhammad Iqbal , Nasir Muhammad , Khan Shamsun N. , Atif Muhammad , Ali Rahat A. , Khalil Syed M. , Rahman Atta-ur
Published: February 2015

Microbial transformation of 11α-hydroxyprogesterone (1) with Cunninghamella elegans, Gibberella fujikuroi, Fusarium lini, and Candida albicans yielded 11α,15α,16α-trihydroxypregn-4- ene-3,20-dione (3), 11α-hydroxy-5α-pregnane-3,20-dione (4), 6β ,11α-dihydroxypregn-4-ene-3,20- dione (5), 11α-hydroxypregna-1,4-diene-3,20-dione (6), 11α,17β -dihydroxyandrost-4-en-3-one (7), and 11α,15α-dihydroxypregn-4-ene-3,20-dione (8). On the other hand, microbial transformation of 17α-hydroxyprogesterone (2) with Cunninghamella elegans and Fusarium lini yielded 11α,17α- dihydroxypregn-4-ene-3,20-dione (9), and 17α-hydroxypregna-1,4-diene-3,20-dione (10). The structures of the metabolites 3 - 10 were deduced on the basis of spectroscopic methods. Compound 3 was identified as a new metabolite, which exhibited a promising inhibitory activity against the α-glucosidase enzyme.
Solid State Syntheses and Structure of LaPdCd2 and PrNi0.951(4)Cd2
Authors: Doğan Ahmet , Rodewald Ute Ch. , Pöttgen Rainer
Published: February 2015

The intermetallic cadmium compounds LaPdCd2 and PrNi0.951(4)Cd2 were synthesized from the elements in sealed tantalum tubes in an induction furnace. Both phases were investigated by X-ray diffraction on powders and single crystals: MgCuAl2-type, Cmcm, Z = 4, a = 431.9(1), b = 1015.7(4), c = 835.7(2) pm, wR2 = 0.0436, 326 F2 values, 16 variables for LaPdCd2 and a = 420.26(8), b = 981.0(2), c = 815.3(1) pm, wR2 = 0.0404, 604 F2 values, 17 variables for PrNi0.951(4)Cd2. A small nickel deficit was observed for the PrNi0.951(4)Cd2 crystal. The cadmium atoms build up orthorhombically distorted three-dimensional networks (Cd-Cd distances: 302 - 334 pm) that resemble the structure of hexagonal diamond, lonsdaleite. Together with the palladium (nickel) atoms, [PdCd2] and [Ni0.951(4)Cd2] networks are formed which leave distorted hexagonal channels for the rare earth atoms.
Kristallstruktur und Eigenschaften von Chrom(II)-Tetrachloroaluminat/Crystal Structure and Properties of Chromium(II)-Tetrachloroaluminate
Authors: Müller Rainhard , Vajenine Grigori V. , Keßler Ulrich
Published: February 2015

Chromium(II)tetrachloroaluminate can be prepared by reaction of chromium, chromium trichloride and aluminum trichloride in the molar ratio 1 : 1.94 : 5.79 or by reaction of stoichiometric amounts of chromium dichloride and aluminum trichloride. Sublimation of the compound yields phase-pure samples of colourless crystals. Cr(AlCl4)2 crystallizes in the non-centrosymmetric orthorhombic space group Pca21 (No. 29), a = 1511.38(3), b = 604.71(1), c = 1301.76(3) pm. The aggregation of Cr(AlCl4)2 molecules leads to a square-bipyramidal coordination of the chromium atom typical of high-spin d4 ions due to the Jahn-Teller effect. The relationship to centrosymmetric Pd(AlCl4)2 (P21/c) which is built up of similar molecules was established by means of a group-subgroup symmetry tree. The temperature dependence of the magnetic susceptibility agrees with Curie-Weiss behaviour (μeff = 4.70 μB,Θ = −1.3 K).
Rare Earth-rich Magnesium Compounds RE4RhMg (RE = Y, La–Nd, Sm, Gd–Tm, Lu)
Authors: Tuncel Selcan , Rodewald Ute Ch. , Chevalier Bernard , Pöttgen Rainer
Published: February 2015

The series of magnesium compounds RE4RhMg (RE = Y, La-Nd, Sm, Gd-Tm, Lu) was prepared by high-frequency melting of the elements in sealed tantalum tubes. All samples were investigated by powder X-ray diffraction. The structures with RE = Sm, Gd, Dy, Ho, and Er as rare earth metal components were refined from single crystal diffractometer data: Gd4RhIn-type, F4̄3m, Z = 16, a = 1392.1(1) pm, wR2 = 0.060, 616 F2 values, 19 variables for Sm4RhMg, a = 1380.8(2) pm, wR2 = 0.071, 530 F2 values, 19 variables for Gd4RhMg, a = 1366.9(1) pm, wR2 = 0.070, 594 F2 values, 20 variables for Dy4RhMg, a = 1355.7(2) pm, wR2 = 0.077, 578 F2 values, 20 variables for Ho3.52RhMg1.48, and a = 1355.4(2) pm, wR2 = 0.075, 559 F2 values, 20 variables for Er3.94RhMg1.06 .The rhodium atoms have slightly distorted trigonal prismatic rare earth coordination. Condensation of the RhRE6 prisms leads to a three-dimensional network which leaves large voids that are filled by regular Mg4 tetrahedra with a Mg-Mg distance of 312 pm in Sm4RhMg. The magnesium atoms have twelve nearest neighbors (3 Mg + 9 RE) in icosahedral coordination. In the structures with holmium and erbium, the RE1 positions which are not involved in the trigonal prismatic network exhibit RE1/Mg mixing. Shortest distances occur for Sm-Rh (286 pm) within the rigid three-dimensional network of condensed trigonal prisms.
Synthesis, Crystal Structure and Optical Spectra of Yb2[CN2]3
Authors: Reckeweg Olaf , Schleid Thomas , DiSalvo Francis J.
Published: February 2015

Red-orange, transparent single crystals of Yb2[CN2]3 [trigonal, R3̄c (no. 167), a = 630.02(3) and c = 2947.4(2) pm, Z = 6] are obtained by the reaction of Yb, Sn, Zn[CN2] and NaN3 in arc-welded Nb ampoules at 1100 K. The title compound exhibits characteristic C-N bond lengths and angles [d(C-N) = 122.7(3) pm and ∡(N-C-N) = 178.4(5)°, respectively] within the [N=C=N]2− unit as well as the expected fundamental frequencies in its optical spectra (Raman: νs = 1338; δ = 643 / 683 / 695 cm−1; IR: νas = 2005 / 2037; δ = 640 / 679 cm−1). Since Yb2[CN2]3 adopts a corundum-type structure, Yb3+ is octahedrally coordinated by six N atoms of different [CN2]2− anions [d(Yb-N) = 228.6(3) and 233.4(3) pm, 3× each] and every [CN2]2− group has four Yb3+ as next neighbours which form a distorted tetrahedron.
Effect of High-energy Milling on the Solid State Formation of Zinc Manganites (ZnxMn3-xO4, 0.5 ≤ x ≤ 1.5) from the System ZnC2O4 · 2H2O-n MnCO3 (n = 1, 1.5 and 2)
Authors: Berbenni Vittorio , Milanese Chiara , Marini Amedeo
Published: February 2015

By combination of TG/DSC and XRPD measurements it has been shown that zinc manganites form (ZnxMn3−xO4 with 0.5 ≤ x ≤ 1.5) starting from mixtures of zinc oxalate dihydrate and manganese carbonate subjected to mechanical activation by high energy milling. Solid solutions ZnOMn3O4- ZnMn2O4 are the products obtained by the same experimental conditions, when starting from a physical mixture. Furthermore milling, besides changing the enthalpy of dehydration of zinc oxalate, induces a partial formation of amorphous Mn3O4 at r. t. In particular ZnMn2O4 can be prepared by annealing the milled mixture for 18 h at 650 °C while a temperature > 1000 °C is needed to prepare ZnMn2O4 from a physical mixture. Finally, the calorimetric data suggest that the mechanism of the reaction is different in the two kinds of mixtures.
Syntheses and Structures of Two Arene-Ruthenium(II) Complexes with Cyclometalating 2-Pyridyl-m-tolyl Ligands
Authors: Zhang Xiu-Zhen , Yao Wen-Rui , Zhang Qian-Feng , Leung Wa-Hung
Published: February 2015

Reactions of [(η6-C6Me6)RuCl2]2 and [(η6-p-cymene)RuCl2]2 with [Hg(ptpy)2] (Hptpy = 2-pyridyl-m-toluene) in THF afforded [{(η6-C6Me6)Ru(ptpy)}2(μ-Hg2Cl6)] 1 and [(η6-pcymene) Ru(ptpy)(HgCl3)] 2, respectively. The crystal structures of complexes 1 and 2 have been determined by single-crystal X-ray diffraction. The ruthenium atom in both molecules 1 and 2 adopts a pseudo octahedral configuration containing a cyclometalated ptpy ligand. The Ru−C(ptpy) and Ru−N bond lengths in 1 are 2.049(3) and 2.089(2) Å, respectively. The corresponding bond lengths for 2 are 2.025(9) and 2.089(7) Å .
A Spectroscopic and Kinetic Investigation on the Substitution of Fe(III) for Ni(II) in a Siderophore Model
Authors: Barreto Wagner J. , Silva Waléria P. , Scarmínio Ieda S. , Barreto Sônia R. Giancoli , Silva Luís F. Stucchi
Published: February 2015

A kinetic and spectroscopic study was performed on the substitution of Fe(III) by Ni(II) in the water soluble anion [Fe(L1−)2L2−]−, a siderophore model (L− = dopa-semiquinone and L2− = dopacatecholate). The reaction was followed in the UV/vis range through the appearing of an intense band at 592 nm due to the anion complex [Ni(L1−)3]− formed which also presents a resonance Raman effect. The overall reaction obeyed a zero-order rate law at 25, 35, 45, and 50 °C, and the rate constants and thermodynamic parameters have been obtained. A chemometric study based on the Imbrie Q-type factor analysis revealed that the reaction occurred with only one kind of intermediate whose UV/vis spectrum has been calculated.
A Novel Hydrogen-bonded Zigzag Chain Manganese(III) Complex: Synthesis, Crystal Structure and Magnetic Properties
Authors: Kara Hulya
Published: February 2015

The synthesis, crystal structure and magnetic properties of [Mn(III)L(H2O)2]+ClO4 −, 1 [L = N,N′-bis(rac-3,5-dichlorosalicylidenato)-1,2-diaminopropane] are reported. Single crystal X-ray diffraction studies showed the structure to consist of [MnL(H2O)2]+ octahedra, with trans-coordinated water molecules, which are linked into infinite helices by hydrogen bonds. The distorted octahedral manganese(III) centre contains an N2O2O′2 coordination sphere made up of the Schiff base ligand in the equatorial plane. In the axial direction, an elongation of the trans Mn-Owater bonds to 2.165(2) and 2.187(2) Å is observed. Such elongations are typical of d4 systems but in this case may also be attributed to the poorer donor power of the water molecules.
One-pot Green Synthesis for Pyrimido[4,5-d]pyrimidine Derivatives
Authors: Kidwai Mazaahir , Singhal Kavita , Kukreja Shuchi
Published: February 2015

Water has been used efficiently as a solvent for the reaction of barbituric acid, aldehyde and urea or thiourea to yield pyrimido[4,5-d]pyrimidines. This environmentally benign procedure leads to high yields of products of greater purity in a single step using water.
Synthesis Methods For Ce(CrO4)2 · χH2O And Crystal Structures Of K2CrSO7, (NH4)2Cr2O7 And Na2Cr2O7 · 2H2O
Authors: Casari Barbara M. , Eriksson Annika K. , Langer Vratislav
Published: February 2015

New and quick methods to synthesize Ce(CrO4)2 · 2H2O and Ce(CrO4)2 ·H2O, giving high yields, are described. The methods are based on exchange reactions by refluxing in water or on solid state reactions. The first crystal structure containing a chromatosulfato ion is presented. K2CrSO7 belongs to space group P21/n with a = 7.4024(1), b = 7.3908(1), c = 12.9883(2) Å , β = 90.021(1)° and Z = 4. The CrSO7
2− ion, consisting of one chromate group sharing one oxygen atom with one sulfate group, has a pseudo syn-C2v conformation with eclipsed oxygen atoms. K2CrSO7 forms a three dimensional network of CrSO7
2− ions held together by the charge balancing potassium ions, with the general structural features common with dichromate-like structures. The redetermination of the structures of (NH4)2Cr2O7 (space group C2/c, with hydrogen atoms located) and Na2Cr2O7 ·2H2O (space group P21, with hydrogen atoms located and the absolute structure established) are reported
A Salt Metathesis Route To Ruthenium Carbene Complex Isomers With Pyridine Dicarboxamide-Derived Chelate Pincer Ligands
Authors: Wallenhorst Carolin , Axenov Kirill V. , Samec Joseph S. M. , Fröhlich Roland , Erker Gerhard
Published: February 2015

Reaction of the doubly deprotonated pyridine 2,6-dicarboxamido ligand (1) with (PCy3)2Cl2 Ru=CHPh (3a) in THF gave a mixture of (lig)(PCy3)Ru=CHPh isomers (4). The pentane soluble N,N,O-4 isomer was isolated by extraction and characterized by X-ray diffraction. The O,N, O-4 isomer was identified in the residue. Single crystals of the closely related complex (lig)(NHC) Ru=CHPh, O,N,O-5, were obtained from the reaction of 1 with (NHC)(PCy3)Cl2Ru=CHPh (3b) and used for the X-ray crystal structure analysis of the system
Self-Assembly Of 1D- And 3D-Networks Through Non-Coordination Intermolecular Forces: Synthesis And Crystal Structures Of Copper(I) Complexes Based On Pyridazine-Type Ligands
Authors: Plasseraud Laurent , Scheurer Andreas , Hampel Frank
Published: February 2015

Reaction of [Cu2(H3CCN)2(μ-pydz)3][PF6]2 (1) with an excess of pyridazine or phthalazine yielded the novel dinuclear complexes [Cu2(μ-pydz)3(pydz)2][PF6]2 (2) and [Cu2 (μ- pydz)(μ-phtz)2(phtz)2][PF6]2 (5), respectively. Depolymerisation of the coordination polymer 1
∞ {[Cu(μ-pydz)2][PF6]} (3) in dichloromethane by addition of an excess of benzo[c]cinnoline afforded the dinuclear copper(I) salt [Cu2(μ-pydz)2(pydz)2(benzo[c]cinnoline)2][PF6]2 (4). Furthermore, a new route for the preparation of bis(benzonitrile)tris(μ-phthalazine)dicopper(I) bis(trifluoromethanesulfonate), [Cu2(C6H5CN)2(μ-phtz)3][CF3SO3]2 (7), was established from {[Cu(CF3SO3)]2 ・C6H5Me}, phthalazine and benzonitrile via the very air-sensitive intermediate [Cu2(CF3SO3)2(μ-phtz)3] (6). Copper(I) compounds 2, 4, and 7 were completely characterised and the molecular structures confirmed in the solid state by single-crystal X-ray structure determination. The analysis of the packing of the molecules in crystals of 4 and 7 revealed a self-assembly of oneand three-dimensional frameworks, respectively, resulting from intermolecular π-π stacking interactions between pyridazine-type ligands
Synthesis And Spectral, Thermal And Structural Characterization Of A Vitamin B13 Complex Of Nickel(II) With 2-Aminothiazole, Mer-[Ni(HOr)(H2o)2(Ata)2]
Authors: Yeşilel Okan Zafer , Akdağb Kamber , Paşaoğlu Hümeyra , Büyükgüngör Orhan
Published: February 2015

The mer-bis(2-aminothiazole)diaqua-orotato-nickel(II) complex, mer-[Ni(HOr)(H2O)2(ata)2] (1), was synthesized and characterized by spectral (IR and UV/vis) and thermal studies. In addition, the crystal structure of the complex was determined by single crystal X-ray diffraction. The complex crystallizes in the triclinic system, space group P1̅. The orotate ligand is coordinated to the nickel(II) atom through a nitrogen atom of the pyrimidine ring and an oxygen atom of the carboxylate group as a bidentate dianion. The coordination of the Ni(II) ion is extended to six by the two 2-aminothiazoles (ata) and two water molecules. The thermal decomposition has been studied in a static air atmosphere
Chemical Constituents From The Roots And Rhizomes Of Clematis Hexapetala Pall.
Authors: Dong Cai-xia , Shi She-po , Wu Ke-si , Tu Peng-fei
Published: February 2015

A new phenolic glycoside, 2,6-dimethoxy-4-(3-hydroxy-propen-1-yl)phenyl-4-O-α-L-rhamnopyranosyl-( 1 → 6)-β -D-glucopyranoside (1) and a new D-ribono-γ -lactone derivative, 3-O-β -D-glucopyranosyl- 2-hydroxymethyl-D-ribono-γ -lactone (3), together with thirteen known compounds have been isolated from the roots and rhizomes of Clematis hexapetala Pall. The characterization of these compounds was achieved by various chromatographic and spectroscopic methods
Atriplisides A And B, Two New Glycosides From Perovskia Atriplicifolia
Authors: Perveen Shagufta , Malik Abdul , Tareen Rasool Bakhsh , Afza Nighat , Iqbal Lubna
Published: February 2015

The new triterpenoidal and flavonone glycosides atriplisides A and B have been isolated from the ethyl acetate fraction of the whole plant of Perovskia atriplicifolia. Their structures were elucidated on the basis of spectroscopic data, especially 2D NMR techniques including 1H-COSY, HMQC, HMBC, and NOESY
Crystal Structures of New Pyrovanadates A2MnV2O7 (A = Rb, K)
Authors: Yahia Hamdi Ben , Gaudin Etienne , Darriet Jacques
Published: February 2015

The new compounds A2MnV2O7 (A = K, Rb) with structures related to the melilite-type have been synthesized by a solid state reaction route. The crystal structures of K2MnV2O7, Rb2MnV2O7 and KRbMnV2O7 have been determined using X-ray single crystal diffraction data. The compound K2MnV2O7 crystallizes with a melilite-type structure with tetragonal unit cell parameters a = 8.609(3), c = 5.538(4) Å and space group P4̅21m. The structures of Rb2MnV2O7 and KRbMnV2O7 are derived from the melilite-type structure with space group P4̅2/mnm and unit cell parameters a = 8.577(6), c = 11.809(6) Å , and a = 8.530(6), c = 11.466(5) Å , respectively. The three structures consist of [MnV2O7]2− layers perpendicular to the c axis separated by A+ layers. The [MnV2O7]2− layers feature corner-sharing MnO4 tetrahedra and V2O7 pyrovanadate units, the linkage leading to rings of five tetrahedra. The doubling of the c parameter for Rb2MnV2O7 or RbKMnV2O7 is explained by the existence of a mirror plane perpendicular to the [001] direction between two [MnV2O7]2− layers. The A+ alkali cations occupy distorted square antiprisms of oxygen atoms in K2MnV2O7 and distorted square prisms of oxygen atoms in Rb2MnV2O7and RbKMnV2O7.
Magnetic Properties and Specific Heat Studies of the Plumbides CeTPb (T = Cu, Pd, Ag, Au)
Authors: Hermes Wilfried , Rayaprol Sudhindra , Pöttgen Rainer
Published: February 2015

The cerium plumbides CeCuPb, CePdPb, CeAgPb, and CeAuPb have been synthesized from the elements in sealed tantalum tubes in a high-frequency furnace followed by annealing. The copper, silver and gold compounds crystallize with the NdPtSb-type structure, space group P63mc: a = 466.1(2), c = 778.1(3) pm for CeCuPb, a = 484.8(2), c = 773.0(3) pm for CeAgPb, and a = 480.24(9), c = 772.9(2) pm for CeAuPb. CePdPb crystallizes with the ZrNiAl-type structure: P6̅2m, a = 775.0(2), c = 413.32(8) pm. The dc susceptibility measurements show trivalent cerium for all four plumbides with experimental magnetic moments of 2.53(2), 2.71(2), 2.63(2), and 2.58(2) μB/Ce atom for CeCuPb, CePdPb, CeAgPb, and CeAuPb, respectively. The compounds CeCuPb, CeAgPb, and CeAuPb, studied by dc susceptibility and specific heat measurements, order antiferromagnetically at N´eel temperatures of 8.2(1), 7.4(1), and 3.7(1) K, respectively.
Magnesium Hydride: From the Laboratory to the Tank
Authors: Roquefere Jean-Gabriel , Bobet Jean-Louis
Published: February 2015

Magnesium metal is under extensive study for its high hydrogen absorption capacity. The main results obtained by the authors, going from the effects of ‘reactive mechanical grinding’ to the addition of nano oxides or to the deposition of nanoparticles are reported and discussed. The absorption properties are compared with the results of other research groups. An improvement of kinetics has been achieved and the mechanisms of the hydrogenation reaction is almost fully understood, but the effects of catalysts are still subject to hypotheses. Recent developments of MgH2 tanks are also presented.
Hydriding Properties of MgH2-Mg2Ni0.8Co0.2 Composites Obtained by Ball Milling
Authors: Mandzhukova Tsveta , Bobet Jean-Louis , Khrussanova Maria , Peshev Pavel
Published: February 2015

The hydrogen absorption-desorption characteristics of composites consisting of 90 wt.% MgH2- 10 wt.% Mg2Ni0.8Co0.2 prepared by ball milling for 30 and 180 min under argon have been investigated. The results obtained have been compared with those for the 90 wt.% Mg-10 wt.% Mg2Ni0.8Co0.2 composite synthesized in the same medium after 30 min of milling. The presence of the Mg2Ni0.8Co0.2 phase has been found to improve the hydriding kinetics of magnesium, the absorption capacity remaining high at temperatures below 573 K. The use of magnesium hydride instead of magnesium has proved to have a favorable effect on the properties of the composites after prolonged activation in an inert medium. It has been established that the absorption-desorption characteristics of the composite 90 wt.% MgH2-10 wt.% Mg2Ni0.8Co0.2 activated mechanically for 180 min are comparable with those of the composite 90 wt.% Mg-10 wt.% Mg2Ni0.8Co0.2 after mechanical activation for only 30 min. The favorable absorption-desorption characteristics of the composites have been explained with the catalytic effect of the additive, the presence of magnesium hydride and the duration of ball milling.
Chemical Bonding and Physical Properties of Yb5Bi3
Authors: Liang Ying , Cardoso-Gil Raul , Schnelle Walter , Schmidt Marcus , Zhao Jing Tai , Grin Yuri
Published: February 2015

The binary compound Yb5Bi3 was synthesized by reaction of the elements in a sealed Ta container. Its crystal structure was determined from single-crystal X-ray diffraction data: β -Yb5Sb3-type, space group Pnma, Pearson code oP32, a = 12.6375(6), b = 9.7243(4), c = 8.4117(5) Å, V = 1033.72(9) Å3, Z = 4, Rgt(F) = 0.028, wRref(F2) = 0.069, T = 290 K. Band structure calculations and analysis of the chemical bonding suggest mainly ionic interactions in the crystal structure and a possible presence of ytterbium in two valence states Yb2+ and Yb3+. The magnetization measurements showed that at low temperatures Yb5Bi3 contains ytterbium exclusively in the 4f14 configuration without fluctuations to the Yb 4f13 configuration up to 400 K. From the Yb-LIII X-ray absorption spectroscopy data the effective valence of ytterbium was found to be 2.11 (89% of Yb in 4f14 configuration).
Chemical Bonding in Metallic Rutile-type Oxides TO2 (T = Ru, Rh, Pd, Pt)
Authors: Demazeau Gérard , Matar Samir F. , Pöttgen Rainer
Published: February 2015

Synthesis routes to rutile-type oxides with 4d and 5d transition elements are summarized. Trends in electronic structure have been established through an analysis in the framework of density functional theory presenting the band structure, the density of states and the properties of chemical bonding. The metal-oxygen bond is found to play the major role in bonding of the system in the valence band. Throughout the series 4d → 5d (RuO2, RhO2, PdO2 and PtO2) the crystal field analysis of the band structure shows a lowering of eg towards t2g manifolds and a broadening of the overall density of states. In the vicinity of the Fermi level the role of the antibonding metal-oxygen character is investigated in the context of instability towards possible magnetic polarization, especially for RuO2.
Low-temperature Properties of U2Co2InH1.9
Authors: Havela Ladislav , Miliyanchuk Khrystyna , Pereira Laura C. J. , Šantavá Eva
Published: February 2015

U2Co2InH1.9, synthesized by high-pressure hydrogenation of U2Co2In, crystallizes in the tetragonal structure similar to the parent compound, expanded by 8.4 %. Although U2Co2In is a weak paramagnet, its hydride shows properties suggesting a proximity to the magnetic order. Its magnetic susceptibility exhibits a maximum at T = 2.4 K, ascribed to spin fluctuations. Magnetization at low temperatures goes through a metamagnetic transition between 2 - 3 T. The specific heat characteristics, with a pronounced upturn of Cp/T vs. T at low temperatures which can be fitted using an additional −T 1/2 term, resemble the behaviour of U2Co2Sn. The γ coefficient of the electronic specific heat, reaching 244 mJ mol−1 K−2, is gradually suppressed by high magnetic fields.
Synthesis of Some Ethyl 3-(Aryldiazenyl)-7-oxo-dihydropyrido[ 2,3-f]quinoxaline-8-carboxylates
Authors: Zahra Jalal A. , Khanfar Monther A. , El-Abadelah Mustafa M. , Thaher Bassam A. Abu , El-Abadla Naser S. , Voelter Wolfgang
Published: February 2015

Ethyl 7,8-diamino-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylate (6) and its free acid 7 are prepared by chemical reduction of the respective 7-azido-8-nitroquinoline 5. Consecutive nucleophilic addition and cyclocondensation reactions of 6 with α-acetyl-N-arylhydrazonoyl chlorides 8a - c in ethanol and triethylamine are site-selective and yield the corresponding 3-(aryldiazinyl)- 2-methylpyrido[2,3- f ]quinoxalines 10a - c. Analytical and spectral (IR, MS, NMR) data of 6, 7, and 10a - c are in conformity with the assigned structures.