bluuebunny/crossref_metadata_2025 huggingface dataset:
Ordnung und Fehlordnung der Anionen in tetragonalen Boridcarbiden der Seltenerdmetalle / Order and Disorder of Anions in Tetragonal Boride Carbides of Rare Earth Metals
Authors: Oeckler Oliver , Mattausch Hansjürgen , Bauer Josef , Simon Arndt
Published: August 2018

Compounds that feature the metal atom substructure of “La5B2C6” are known for most rare earth metals (Ln). They are characterized by two types of voids surrounded by large bicapped tetragonal antiprisms and smaller distorted octahedra, respectively. For many rare earth elements, a huge variation of lattice parameters has been observed for the corresponding compounds. A series of structure determinations has beed performed in order to elucidate the reasons for this remarkable stability range. The compounds of the earlier lanthanoids (La-Nd) exhibit broad ranges of homogeneity that are due to varying occupancy of octahedral voids which can be empty or filled by varying amounts of C atoms or C2 groups. However, the larger voids are fully occupied with disordered C3B groups. In most cases the disorder is completely statistical with only a few exceptions. In contrast, two different phases have been observed in the case of late rare earth metals (starting from Gd). Their ranges of homogeneity are moderate, and the larger voids are fully occupied by ordered CBC entities. The difference between these two types of phases concerns the octahedral voids which contain C atoms in the case of compounds with the idealized composition Ln5B2C5 and C2 groups for Ln5B2C6, respectively. Positional disorder is possible for both C atoms and C2 groups. Therefore, no single well-defined compound is known that possesses the metal atom arrangement of “La5B2C6”.
Binuclear Ten-Membered Ring Cyclometallated Complexes of Digold(I) and their Reactions with Iodine and Bromine
Authors: Bennett Martin A. , Bhargava Suresh K. , Hockless David C. R. , Mohr Fabian , Watts Kellie , Welling Lee L. , Willis Anthony C.
Published: August 2018

The cyclometallated digold(I) complexes [Au2(μ-2-C6H4CH2PPh2)2] (10) and [Au2(μ-2-CH2C6H4PPh2)2] (11) have been synthesized by the reaction of Li[2-C6H4CH2PPh2] and Li[2-CH2C6H4PPh2], respectively, with [AuBr(PEt3)]. A single crystal X-ray structure analysis of 10 shows the linearly coordinated gold(I) atoms to be separated by 3.0035(9) Å in a puckered ten-membered ring. Both complexes add one mol equivalent of iodine to form initially gold(I)-gold(III) complexes [Au(μ-2-C6H4CH2PPh2)2AuI2] (14a) and [Au(μ-2-CH2C6H4PPh2)2AuI2] (17), which isomerize to the corresponding salts [Au(κ2-P,C-C6H4CH2PPh2)2][AuI2] (13a) and [Au(κ2-P,C-CH2C6H4PPh2)2][AuI2] (16). In 13a the gold(III) cation is planar coordinated by a pair of chelate P-C donor ligands, the phosphorus and carbon atoms being, separately, mutually cis, as shown by X-ray structural analysis. From the reaction of 10 with 2 mol equivalents of bromine, the neutral chelate complex [AuBr2(κ2-P,C-C6H4CH2PPh2)] (15) has been isolated and structurally characterized.
Bis-, Tris- and Tetrakis(lithiomethyl)germanes: New Building Blocks for Organogermanium Compounds
Authors: Strohmann Carsten , Wack Eric
Published: August 2018

Bis(lithiomethyl)germanes, R2Ge(CH2Li)2, tris(lithiomethyl)germanes, RGe(CH2Li)3, and tetrakis( lithiomethyl)germane, Ge(CH2Li)4, were prepared by the reductive C-S bond cleavage with lithium naphthalenide (LiC10H8) or lithium p,p’-di-tert-butylbiphenylide (LiDBB) and characterized by trapping with Bu3SnCl. The bis(lithiomethyl)germanes were used for the synthesis of 1,1-dimethyl-3,3-diphenyl-1-germa-3-silacyclobutane, 1,1-diethyl-3,3-diphenyl-1-germa-3-silacyclobutane, 1,1,3,3-tetraphenyl-1-germa-3-silacyclobutane and 1,1,3,3-tetraphenyl-1,3-digermacyclobutane. The single-crystal X-ray diffraction studies of methyltris(phenylthiomethyl)germane and tetrakis(phenylthiomethyl)germane, starting materials for the corresponding poly(lithiomethyl) germanes, indicate tetrahedrally arranged substituents at the germanium atoms.
Gold-Thiolate Clusters: A Relativistic Density Functional Study of the Model Species Au13(SR)n, R = H, CH3, n = 4, 6, 8
Authors: Genest Alexander , Krüger Sven , Gordienko Alexei B. , Rösch Notker
Published: August 2018

The binding of sulfanyl and alkylsulfanyl model ligands to gold clusters was studied for the case of Au13(SR)n with R = H, CH3 and n = 4, 6, 8. Accurate all-electron electronic structure calculations and geometry optimizations of these gold-thiolate clusters have been performed with a scalar relativistic Kohn-Sham procedure as implemented in the density functional program PARAGAUSS. In all structures obtained, bridge coordination was preferred for both types of ligands; no higher coordinated sites where occupied. While in many cases ligand decoration did not change the overall structure of the Au13 core, also more open structures with Au-Au distances elongated beyond the bulk value have been obtained. The effects due to increasing ligand decoration were small: a small decrease of the binding energy per ligand does not exclude higher ligand coverages. The differences between the model ligands SH and SCH3 were consistent in all cases considered: SCH3 exhibits weaker binding and a slightly smaller charge separation between cluster core and ligand shell, which amounts up to about 1.5 e for 8 ligands. Overall, the Au13 core of the clusters was found to be quite flexible. This can be rationalized by the fact that the calculated binding energy per ligand is comparable or even exceeds the binding energy per atom in Au13.
Mono- and Binuclear Gold(I) Amido Compounds of Purine Derivatives
Authors: Horvath Ulrike E. I. , Cronje Stephanie , McKenzie Jean M. , Barbour Leonard J. , Raubenheimer Helgard G.
Published: August 2018

A series of neutral dinuclear and mononuclear gold(I) complexes with phosphine and N-bonded 9H-purin-9-ate or 9H-purin-6-ylamine-9-ate have been synthesised under basic conditions and characterised by gHSQC, 1H,13C gHMQC and 1H detected 1H,15N gHMQC experiments in addition to ESI-MS and IR spectroscopy. Intermolecular aurophilic interactions are present in the structures of polymeric 1,2-bis(diphenylphosphine)ethane(9H-purin-9-ate)gold(I) 1, (3.1641(4) Å ) and 1,3- bis(diphenylphosphine)propane(9H-purin-9-ate)gold(I) 3, (3.52Å ). The N-Au-P angle in 1 is exceptionally small (166.3(1)°). Intramolecular aurophilic interaction (3.63 Å ) complemented by hydrogen bonding dictates the non-oligomeric structure of 1,3-bis(diphenylphosphine)propane(9H-purin- 6-ylamin-9-ate)gold(I) (7). Dimeric aurophilic interactions appear in the structure of (tributylphosphine)( 9H-purin-9-ate)gold(I) (11) (3.2311(7) Å ), while the structure in the other mononuclear compound, (triphenylphosphine)(9H-purin-9-ate)gold(I) (9) is organised by Au. . .N-interactions.
Crystal Structure and Magnetic Exchange Interaction in a Binuclear Copper(II) Schiff Base Complex with a Bridging m-Phenylenediamine Ligand
Authors: Zeyrek C. T. , Elmali A. , Elerman Y. , Svoboda I.
Published: August 2018

Condensation of 2-hydroxy-3-methoxybenzaldehyde with m-phenylenediamine (1,3-diaminobenzene) (m-pda) gives the ligand [N,N′-bis(2-hydroxy-3-methoxybenzylidene)-1,3-diaminobenzene] which reacts with cupric acetate to give the complex [Cu2(L-m-pda)2]·2H2O, [L = 2-hydroxy-3- methoxybenzaldehyde)]. The molecular structure of the complex [Cu2(L-m-pda)2]·2H2O has been determined by single-crystal X-ray analysis. (C44H40Cu2N4O8)·2H2O, triclinic, space group P1̄. Two [Cu(L-m-pda)] fragments, related by an inversion center, are connected by m-phenylene groups to form a binuclear unit. The coordination geometry around each copper(II) can be described as a distorted tetrahedron formed by the N2O2 donor set of the Schiff base ligands. The intramolecular Cu···Cu separation is 7.401(6) Å. The magnetic susceptibility of the complex in the 5 - 301 K temperature range can be rationalized by the parameters J = −0.4 cm−1 and g = 2.17. This indicates a weak intramolecular antiferromagnetic interaction. Extended Hückel molecular orbital (EHMO) calculations have been performed in order to gain insight into the molecular orbitals that participate in the super-exchange pathway.
2,9-Dimethyl-1,10-phenanthroline as Ligand in the Holo- and Hemidirected 1:1 and 1:2 Lead(II) Complexes
Authors: Morsali Ali
Published: August 2018

1:1 and 1:2 lead(II) complexes with 2,9-dimethyl-1,10-phenanthroline (Dmphen), {[Pb(Dmphen)(NO3)n] and [Pb(Dmphen)2(ClO4)2]} have been synthesized and characterized by CHN elemental analysis, IR, 1H NMR, 13C NMR and 207Pb NMR spectroscopy. The structure of these complexes was confirmed by X-ray crystallography. The single crystal X-ray data of [Pb(Dmphen)(NO3)n] show the complex to be polymeric and the Pb atom to have an unsymmetrical eight-coordinate geometry, the coordination being holodirected, whereas the [Pb(Dmphen)2(ClO4)2] complex is monomeric and the Pb atom has an unsymmetrical eight-coordinate geometry with the coordination hemidirected.
Auration of the Sulfones MeSO2CH2CN and CH2(CH2SO2)2CH2
Authors: Djordjevic Bratislav , Schuster Oliver , Schmidbaur Hubert
Published: August 2018

MeSO2CH2CN shows considerable C-H acidity at its methylene group. Through lithiation followed by reaction with (Ph3P)AuCl it can therefore be readily converted into the dinuclear, geminally substituted product MeSO2C[Au(PPh3)]2CN. With an excess of aurating reagents, a third [(Ph3P)Au] group becomes N-bonded to the nitrile unit to give an ionic trinuclear compound {MeSO2C[Au(PPh3)]2CNAu(PPh3)}+BF4
−. The same product is obtained by direct reaction of MeSO2CH2CN with [(Ph3P)Au]BF4. The crystal structures of the two products have been determined. The diaurated sulfone parts of the molecule and the cation are virtually superimposible. Small Au-C-Au angles and short Au-Au contacts suggest significant aurophilic interactions (“Aframe” structures). The small -C≡N-Au angle of 165.6(5)° in the cation indicates that the strong [(Ph3P)Au]+ acceptor causes substantial changes in the bonding of the nitrile group. Dilithiation of 1,3-dithiane-S,S’-tetroxide followed by reaction with 2 equivalents of (Ph3P)AuCl affords the geminally diaurated compound CH2(CH2SO2)2C[Au(PPh3)]2.
Synthesis, Crystal Structure and Vibrational Spectrum of Cobalt(II)orotate Trihydrate, [Co(C5N2O4H2) · 3 H2O
Authors: Brockner Wolfgang , Branscheid Robert , Gjikaj Mimoza , Adam Arnold
Published: August 2018

Cobalt orotate trihydrate, [Co(C5N2O4H2)]·3H2O, has been synthesized and its crystal structure determined. The title compound crystallizes in the orthorhombic space group P212121 (no. 19) with a = 771.5(2), b = 788.9(7), c = 1470.4(2) pm, and Z = 4. Bridging orotate anions coordinate in a mono- and bidentate manner to the Co atom resulting in infinite chains of alternating Co(II) cations and orotate (OrH2−) anions parallel to the c axis. The distorted octahedral Co coordination geometry is completed by three H2 molecules. The FT-Raman and FT-IR spectra of the crystalline compound have been recorded and an assignment of the vibrational modes is proposed. The thermal behavior (TG) was investigated.
Orthoamide, LXII [1]. – Mikrowellen-unterst ¨ utzte Formylierung schwach CH2-acider Verbindungen mit dem Bredereck-Simchen Reagenz – Umwandlung der Kondensationsprodukte in Heteroaromaten / Orthoamides, LXII [1]. – Microwave Assisted Formylation of Weak CH2-Acidic Compounds with the Bredereck-Simchen Reagent – Preparation of Heteroaromatic Compounds from the Condensation Products
Authors: Kantlehner Willi , Simchen Gerhard , Mezger Jochen , Stoyanov Edmont V. , Kreß Ralf , Frey Wolfgang , Sievers Björn
Published: August 2018

The diformylation of the dinitriles 4 and diesters 7 with the Bredereck-Simchen reagent HC[N(CH3)2]2[OC(CH3)3] (1) under microwave irradiation give the bis-enamines 6 and 8 with dramatically reduced reaction times and improved yields compared to conventional heating. The condensation products formed can be easily converted to bis-pyrazole and bis-isoxazole derivatives 13 and 20, respectively. Methyl anthranilate reacts on prolonged heating with the orthoamide 21 to give ketene aminal 23 in low yield (8 %). Under microwave irradiation the same reagents lead to a mixture of 23 (14 %) and dihydropyrane 24 (28 %).
The Mo2FeB2- and Mn2AlB2-Type Modifications of RE2Ni2Cd (Re = La, Pr, Nd, Sm, Tb, Dy)
Authors: Fickenscher Thomas , Rodewald Ute C. , Niepmann Dirk , Mishra Ratikanta , Eschen Marcus , Pöttgen Rainer
Published: August 2018

The rare earth metal (RE)-nickel-cadmium intermetallics RE2Ni2Cd (RE = La, Pr, Nd, Sm, Tb, Dy) were prepared from the elements in sealed niobium or tantalum tubes in a water-cooled sample chamber of a high-frequency furnace. They crystallize with a tetragonal Mo2FeB2 type low-temperature modification, space group P4/mbm, and an orthorhombic Mn2AlB2 type hightemperature modification, space group Cmmm. The cadmium compounds were characterized through their X-ray powder patterns. Five structures of the low-temperature modifications were refined from X-ray single crystal diffractometer data: α = 763.76(9), c = 387.26(8) pm, wR2 = 0.046, 205 F2 for La2Ni1.67(1)Cd; α = 752.93(7), c = 380.95(6) pm, wR2 = 0.061, 260 F2 for Pr2Ni2Cd; α = 750.88(9), c = 378.33(7) pm, wR2 = 0.051, 195 F2 for Nd2Ni2Cd; α = 743.6(1), c = 374.0(1) pm, wR2 = 0.036, 386 F2 for Sm2Ni1.93(1)Cd; α = 734.9(1), c = 366.1(2) pm, wR2 = 0.030, 252 F2 for Dy2Ni1.94(1)Cd, with 13(12) variables per refinement. The 4g nickel site is only fully occupied in the neodymium and the praseodymium compound. Both modifications can be considered as intergrowths of distorted AlB2 and CsCl related slabs. In both modification the nickel and cadmium atoms build up two-dimensional [Ni2Cd] networks. In the low-temperature modifications the nickel atoms form pairs, while nickel zig-zag chains occur in the high-temperature modifications. These nickel fragments are condensed via the cadmium atoms. The crystal chemistry and the chemical bonding in these intermetallics is discussed
Neue Chalcogenophosphate: KBaPS4, KBaPSe4 und Ba3PO4PSe4 / New Chalcogenophosphates: KBaPS4, KBaPSe4, and Ba3PO4PSe4
Authors: Jörgens Stefan , Mewis Albrecht
Published: August 2018

Colourless single crystals of KBaPS4 (a = 11.587(2), b = 6.700(1), c = 10.118(2) Å ), and pale orange ones of KBaPSe4 (a = 11.972(2), b = 6.973(1), c = 10.388(2) Å ) were obtained by reactions of Ba3(PS4)2 and Ba3(PSe4)2, respectively, with KCl (790 °C; 30 h). The isotypic compounds crystallize with a slightly modified TlEuPS4 type structure (Pnma, Z = 4); that is, the characteristic units are distorted discrete PX4 tetrahedra (X: S, Se) interconnected by K+ and Ba2+. However, due to the strong distortion of the trigonal X6 prisms along [001] the coordination numbers increase from 8 to 9 for the barium atoms and from 8 to 11 for the potassium atoms. Orange crystals of Ba3PO4PSe4 (a= 6.779(1), b =7.108(1), c =12.727(3)Å ; α = 82.45(3)°, β =78.88(3)°, γ =81.34(3)°) resulted as a by-product of the synthesis of Ba3(PSe4)2. The compound crystallizes in a new type of structure (P1̅; Z = 2) and is the first chalcogenophosphate with discrete PO4 and PSe4 tetrahedra. The coordination polyhedra of the barium atoms are formed by both chalcogen atoms
Structure Refinement of the S-Phase Precipitate MgCuAl2
Authors: Heying Birgit , Hoffmann Rolf-Dieter , Pöttgen Rainer
Published: August 2018

The technologically important S-phase precipitate MgCuAl2 has been synthesized from the elements in a sealed tantalum tube in an induction furnace. The aluminide was investigated by powder and single crystal X-ray diffraction methods: Cmcm, a = 401.19(9), b = 926.5(2), c = 712.4(1) pm, wR2 = 0.0425, 234 F2 values, and 16 variable parameters. The new crystallographic data fully confirm the original work by Perlitz and Westgren [Ark. Kemi, Mineral. Geol. 16, 1 (1943)], but the present structure refinement has led to a much higher precision. The crystal chemical peculiarities of MgCuAl2 are briefly discussed.
The Ordered Laves Phases CeNi4Cd and RECu4Cd (RE = Ho, Er, Tm, Yb)
Authors: Doğan Ahmet , Pöttgen Rainer
Published: August 2018

The ternary ordered Laves phases CeNi4Cd and RECu4Cd (RE = Ho, Er, Tm, Yb) were synthesized by induction-melting of the elements in sealed tantalum tubes. The compounds were characterized by X-ray powder and single crystal diffraction: MgCu4Sn type, F 4̄3m, a = 706.9(2) pm for CeNi4Cd, a = 723.1(2) pm for HoCu4Cd, a = 717.7(3) pm for ErCu4Cd, a = 714.2(1) pm for TmCu4Cd, and a = 713.10(7) pm for YbCu4Cd. The nickel and copper atoms build up threedimensional networks of corner-sharing Ni4/2 and Cu4/2 tetrahedra. These networks leave voids of coordination number 16 that are filled with the rare earth (RE) and cadmium atoms.
Tannins and Flavonoids from the Erodium cicutarium Herb
Authors: Fecka Izabela , Cisowski Wojciech
Published: August 2018

A new depside, erodiol, was isolated and identified from the aerial parts of Erodium cicutarium (Geraniaceae), together with essential compounds such as: geraniin, didehydrogeraniin, corilagin, (-) 3-O-galloylshikimic acid, methyl gallate 3-O-β -D-glucopyranoside, rutin, hyperin, quercetin 3- O-(6”-O-galloyl)-β -D-galactopyranoside, isoquercitrin and simple phenolic acids. Their chemical structures were elucidated by means of spectroscopic (ESI MS, HRESI MS, 1D and 2D NMR) evidence.
Fragmentable Heterogeneous Cocatalysts for the Metallocene-Catalyzed Polymerization of Olefins, I. Surface Modification of Silica and Characterization of the Resulting Carriers
Authors: Schumann Herbert , Widmaier Ralf , Lange Katharina C. H. , Wassermann Birgit C.
Published: August 2018

Surface modification of pre-dried spherical silica nano-particles with diameters of 235 nm and 10 to 20 nm and of commercially available non-spherical silica materials using various aminoalkyltrialkoxysilanes and α-ω-bis(alkoxysilyl)organyls (organyl = alkanediyl, aminoalkanediyl, polyether, polysiloxane) has been performed in suspension in solvents with water. The quantity of water has a dominating influence, as compared to the amounts and the ratios of silanes employed, on the surface morphology of the modified silicas. The morphologies observed range from weakly linked aggregates of spherical particles to large agglomerates covered by thick irregular layers of organopolysiloxane, as demonstrated by scanning electron microscopy. These carriers can be modified further with organoaluminium compounds to yield heterogeneous cocatalysts for the polymerization of ethylene.
Spiranoid Withanolides from Jaborosa odonelliana and Jaborosa runcinata
Authors: Cirigliano Adriana M. , Misico Rosana I.
Published: August 2018

Two new spiranoid withanolides, (20R,22R,23R)-12β ,17β ,22-trihydroxy-1-oxo-12,23-cycloergosta- 2,24-dien-26,23-olide (3) and (23R)-5α,6β ,12β ,21-tetrahydroxy-1,22-dioxo-12,23-cycloergosta- 2,17,24-trien-26,23-olide (4) were isolated from plants of Jaborosa odonelliana and Jaborosa runcinata, respectively. Compounds 3 and 4 were characterized by a combination of spectroscopic methods (1D and 2D NMR, MS) and molecular modelling.
Terpenes from Mikania aff. jeffreyi (Asteraceae)
Authors: Mendes Carla C. , Cruz Frederico G. , Guedes Maria Lenise da S. , Roque Nidia F.
Published: August 2018

Ten terpenes, three steroids and one flavone have been isolated from the leaves of Mikania aff. jeffreyi, Asteraceae. Among them there are two new kaurane and one new bis-norlabdane diterpene derivatives. The kaur-16-en-18-oic acid, 4-epi-kaurenoic acid, is predominant in the plant leaves. The structures were elucidated by spectroscopic analysis.
The Five-, Six- and Seven-Vertex Dicarbaboranes, Monocarbaborane Anions and Borane Dianions with closo Structures. Nuclear Spin-Spin Coupling Constants Calculated by DFT Methods
Authors: Wrackmeyer Bernd
Published: August 2018

Five-, six- and seven-vertex dicarbaboranes, carborane anions and borane dianions have been studied by DFT calculations at the B3LYP/6-311+G(d,p) level of theory, aiming at determining the indirect nuclear spin-spin coupling constants with an emphasis on J(11B,11B), J(13C,11B) and J(13C,13C). The reasonable agreement with all experimental data suggests that the calculated data can be used in the discussion of the bonding situation in these cluster compounds, for which many coupling constants cannot be determined experimentally. The delocalisation of electron density is reflected by changes in both magnitude and sign of the coupling constants. The trend in the coupling constants between nuclei in antipodal positions points towards direct bonding interactions.
Isoflavonoids from Seeds of Millettia griffoniana (Bail), 15
Authors: Ngamga Dieudonne , Yankep Emanuel , Tane Pierre , Bezabih Merhatibeb , Ngadjui Bonaventure T. , Fomum Zacharia T. , Abegaz Berhanu M.
Published: August 2018

Three new isoflavonoids, griffonianone F, G and H were isolated from the seeds of Millettia griffoniana, along with the known prebarbigerone, pseudobaptigenin, pseudobaptigenin methyl ether, tephrosin, dipterixine, odorantine, 7,4’,5’-tetramethoxyisoflavone and isojamaicin. Their structures were assigned on the basis of spectroscopic data and chemical transformations.
Syntheses and Spectroscopic Studies of Some New Diazaphospholes and Diazaphosphorinanes. Crystal Structure of 4
Authors: Gholivand Khodayar , Shariatinia Zahra , Pourayoubi Mehrdad , Farshadian Sedigheh
Published: August 2018

New diazaphospholes and diazaphosphorinanes with formula

were synthesized and characterized by 1H, 13C, 31P NMR and IR spectroscopy and elemental analysis. The structure of compound 1 has been determined by X-ray crystallography. A one-dimensional polymeric chain was observed in the crystalline lattice produced by intermolecular -P=O. . .H-N- and -C=O. . .H-N-hydrogen bonds. Compounds 1 and 2 contain five-membered rings and show high values for 2J(PNH) and 2J(P,C) coupling constants due to the ring strain. These constants are reduced seriously in compounds with six-membered rings. In compound 6 with CCl3C(O)NH moiety, all phosphorus-hydrogen couplings are zero.
Contribution to the Chemistry of 2,2,6,6-Tetramethylpiperidino Aluminium Compounds
Authors: Knabel Klaus , Nöth Heinrich
Published: August 2018

tmpAlBr2 (tmp = 2,2,6,6-tetramethylpiperidino) was prepared from AlBr3 and tmp2AlBr at 90 °C in the absence of a solvent, but could not be crystallised from toluene or hexane because it reacted with the solvents to form tmpH·AlBr3 in high yield. tmpH·AlMeCl2, obtained from the components, decomposes at elevated temperatures but no tmpAlCl2 could be isolated. Attempts to generate the cation [tmp-Al-tmp]+ from tmp2AlBr or tmp2AlCl by halide abstraction with B(C6F5)3, Ph3C(SnCl5) or SbCl5 or from tmp2AlR (R = Me, Ph) and B(C6F5)3 have failed. An unexpected reaction occurred on treatment of tmp-B=P(tBu)AlBr3 with BH3 in THF which led to the formation of [AlBr2(thf)4][AlBr4]. The attempted synthesis of tBu2Al(tmp) from tBu2AlBr and Li(tmp) gave a product which, on exposure to CO2 at dry ice temperature, yielded the salt [(tBuAl)2(O2C(tmp))3][tBu3Al-Br-AltBu3] in low yield. All isolated products were characterized by NMR spectroscopy and by X-ray determination of their molecular structures.
Surprising Insights in the Various Molecular Structures of Hypercoordinate Bis(oxinato)silicon Complexes
Authors: Wagler Jörg , Schley Michael , Gerlach Daniela , Böhme Uwe , Brendler Erica , Roewer Gerhard
Published: August 2018

The syntheses of two cyclic diorganosilicon enamines

=CH2) [R = Ph (2a), Me (2b)] are described. These compounds react with 8-oxyquinoline leading to bis(oxinato)silicon complexes RPhSi(oxinate)2 [R = Ph (5a), Me (5b)]. Their X-ray structures reveal hexacoordination of the Si atom with the monodentate substituents in cis-positions and N atoms as well as O atoms in trans-positions.

In crystalline dimethylbis(oxinato)silicon, Me2Si(oxinate)2 (7), the silicon atom is only bicapped tetrahedrally coordinated, while for dichlorobis(oxinato)silicon, Cl2Si(oxinate)2 (8), there is an octahedral coordination of the Si atom with chlorine atoms in trans-positions. This conclusion is based on the results of spectroscopic analysis (IR, 29Si CP/MAS NMR) as well as quantum chemical calculations. The first example of a silicon-bis-oxinate with the N→Si dative bonds in a trans-arrangement has been detected in the hexacoordinate silicon tris-chelate (oxinate)2Si(PhN-CH2CH2-NPh) (11). Its configuration was proven by X-ray structure analysis. Thus, for hexacoordinate bis(oxinato)silicon compounds three new architectures were found which complement the previously established building pattern of the N,N’-cis-O,O’-trans-bis(oxinato)silicon complexes.

The mer-tris(oxinato)siliconium cation (9+) (its configuration being proven by 1H and 13C NMR spectroscopy) features at least three coordination patterns with (O,O;N,N)-cis,cis-, -cis,trans- as well as -trans,cis-arrangements of two oxinate ligands.
Stereoselective Synthesis and Single Crystal X-Ray Structures of Some Sterically Congested Electron-poor N-Vinyl Pyrazole Derivatives
Authors: Noshiranzadeh Nader , Ramazani Ali , Mahyaria Amir Tofangchi , Ślepokurab Katarzyna , Lisb Tadeusz
Published: August 2018

A one-pot synthesis of sterically congested electron-poor N-vinyl pyrazoles in fairly good yields by the reaction of ethyl 3-phenyl-2-propynoate, pyrazoles and triphenylphosphine is reported. The structures of these compounds were confirmed by IR, 1H, and 13C NMR spectroscopy, and single crystal X-ray structure determination. The structural analysis of the products indicated that the reaction is completely regio- and stereoselective.
Reaction of Coumarin Derivatives with Nucleophiles in Aqueous Medium
Authors: Kidwai Mazaahir , Priya  , Rastogi Shweta
Published: August 2018

A series of heterocycles was synthesized by the reaction of α,β -unsaturated ketones of benzopyrans or coumarins with various nucleophiles in aqueous medium bearing two points of diversity. Compared to an identical library generated by conventional parallel synthesis, a microwaveassisted procedure dramatically decreased reaction times from hours to minutes, and yields of products and intermediates were improved remarkably. This synthetic approach is ecofriendly in nature which features water as solvent, microwave irradiation, and usage of a “green” catalyst (K2CO3).
Synthesis, Characterization and anti-HIV and Antitumor Activities of New Coumarin Derivatives
Authors: Al-Soud Yaseen A. , Al-Sa’doni Haitham H. , Amajaour Houssain A. S. , Salih Kifah S. M. , Mubarakb Mohammad S. , Al-Masoudic Najim A.
Published: August 2018

A new series of coumarin and benzofuran derivatives were synthesized as potential non-nucleoside reverse transcriptase inhibitors (NNRTIs) by reacting, separately, 4-bromomethylcoumarins, their sulphonyl chlorides, and ethyl 3-(bromomethyl)-6-methoxy-1-benzofuran-2-carboxylate with different imidazoles and their benzo analogs. The antiviral (HIV-1, HIV-2) properties of the newly synthesized compounds were investigated in vitro and all compounds were found to be inactive, except 10 which showed inhibition of HIV-2 with EC50 > 0.51 μgmL−1. The in vitro cytotoxicity of 17 and 19 was assayed against a panel of tumor cell lines consisting of CD4 human T-cells.
A Phenylethanoid Glycoside and Other Constituents from the Fruits of Forsythia koreana
Authors: El-Desouky Samy K. , Kim Young-Kyoon
Published: August 2018

From the methanol extract of the fruits of Forsythia koreana two new compounds, one phenylethanoid glycoside and one pyrrolidine alkaloid, have been isolated together with six known compounds. The structures of the isolated compounds were elucidated on the basis of 1D and 2D NMR spectroscopic methods and comparison with literature data.
Structure and Stability of a Linear Trinuclear Cobalt(II) Complex: Co3(PhCH=CHCO2)6(bpy)2
Authors: Wang Xian-Wen , Chen Ying , Chen Jing-Zhong , Liu Jian-Hong , Han Lei
Published: August 2018

A trinuclear cobalt(II) complex, [Co3(PhCH=CHCO2)6(bpy)2] (1) (bpy = 2,2-bipyridine), was synthesized and structurally characterized by single crystal X-ray diffraction. Complex 1 crystallizes in the triclinic space group P1 with cell parameters: a = 11.347(6), b = 11.471(6), c = 14.247(8) Å , α = 69.503(9), β = 74.211(9), γ = 76.812(11)°, V = 1653.2(15) Å3, Z = 1, and R1(F) = 0.026, wR2(F2) = 0.138. Complex 1 has a linear arrangement of three Co(II) centers bridged by six cinnamate carboxylate groups, four of which function in a bidentate syn-syn fashion linking the peripheral Co2 atoms, and two as both bidentate bridging and bidentate chelating units. The Co1 atom is located on a crystallographic inversion center and exhibits a slightly distorted octahedral coordination geometry, while the terminal Co atoms (Co2 and Co2#1) have a significantly distorted octahedral environment. Hydrogen bonding interactions and π-π stacking interactions stabilize the structure
One-dimensionally Hydrogen-bonded Silver(I) Saccharinate Complexes with N-(2-Aminoethyl)piperidine and N-(2-Hydroxyethyl)piperidine: Synthesis, Crystal Structures, FTIR and Thermal Studies
Authors: Hamamci Sevim , Yilmaz Veysel T. , Büyükgüngör Orhan
Published: August 2018

Two new complexes [Ag(sac)(aepip)] (1) and [Ag(sac)(hepip)] (2) have been obtained by the reaction of AgNO3 with Na(sac)・2H2O (sac = saccharinate) in the presence of N-(2-aminoethyl)piperidine (aepip) and N-(2-hydroxyethyl)piperidine (hepip), and characterized by elemental analysis, IR spectroscopy, thermal analysis and single crystal X-ray diffraction. Complexes 1 and 2 crystallize in the monoclinic space group C2 and triclinic space group P1, respectively. In both complexes, silver( I) is tricoordinated. The sac ligand is N-coordinated, while aepip and hepip behave as N-N and N-O bidentate chelating ligands, respectively. The pip rings of both aepip amd hepip ligands adopt typical ‘chair’ conformation. The individual molecules are linked into one-dimensional chains by two N-H···O hydrogen bonds in 1, and one O-H···O hydrogen bond in 2. TG-DTG curves illustrated that the endothermic elimination of aepip and hepip ligands takes place in the early stages of thermal decomposition, while that of the sac moiety occurs exothermically at higher temperatures to give metallic silver
Tribochemical Synthesis and Structure of K2BiF5
Authors: Beck Horst P. , Becker Daniel , Haberkorn Robert
Published: August 2018

The synthesis of K2BiF5 by a tribochemical reaction is reported. This compound crystallises in a K2SmF5-type arrangement with the lattice parameters a = 11.3862(2), b = 7.5480(1), c = 6.6008(1) Å and space group Pnma. The effect of substituting Bi into the K2SmF5-type structure is discussed in comparison with other compounds considering the effect of the lone-pair activity of Bi3+.
Benzyl Complexes of Lanthanide(II) and Lanthanide(III) Metals: Trends and Comparisons
Authors: Harder Sjoerd , Ruspic Christian , Bhriain Nollaig Ní , Berkermann Frederic , Schürmann Markus
Published: August 2018

A variety of benzyllanthanide complexes have been prepared by the metathesis reaction of benzylpotassium precursors with lanthanide halides. Syntheses and crystal structures for the following complexes are described: [2-Me2N-α-Me3Si-benzyl]2Eu(II)·(THF)2 (1-Eu), (2-Me2Nbenzyl) 3Ln(III) (2-Ln with Ln = Nd, Sm, Dy, Ho, Yb), (4-R-C6H4CH2)3Ln·(THF)3 (3-Y: Ln = Y, R = H; 3-La: Ln = La, R = tBu). Complexes of types 1 and 2 are thermally robust on account of a stabilization by a benzylic Me3Si substituent and/or intramolecular coordination of the Me2N substituent. Comparison of the crystal structures of these new series of lanthanide complexes shows several similarities and trends. In addition, comparisons with alkali metal and alkaline earth metal benzyl complexes are made.
Concerted and Diradical Stepwise Mechanisms in the Diels-Alder Reactions of Phosphinine and Phosphinine Sulfide: A DFT Investigation
Authors: Bansal Raj K. , Gupta Neelima , Kumawat Surendra K.
Published: August 2018

Computations of the concerted and diradical stepwise mechanisms of the Diels-Alder (DA) reactions on the >C=P− functionality of phosphinine and phosphinine sulfide with 1,3-butadiene at the density functional theory level B3LYP/6-311++G**//B3LYP/6-31G** give the values of energy of concert as 10.7 and 2.6 kcal mol−1, respectively. Similarly, the DA reaction of dimethyl acetylenedicarboxylate (DMAD) with the −CH=CH−CH=P− moiety of phosphinine or its sulfide has been investigated theoretically at the same level of theory. The results reveal that in the DA reaction of phosphinine, the role of sulfur is to oxidize phosphorus to generate a phosphinine sulfide intermediate, which subsequently undergoes DA reaction with 2,3-dimethylbutadiene or DMAD by a concerted mechanism to afford the respective cycloadducts.
Photocatalytically Active Materials with Pyridinium-enolate Partial Structures
Authors: Schmidt Andreas , Albrecht Marcel
Published: August 2018

2,3-Dichloro-1,4-naphthoquinone and tetrabromo- or tetrachloro-1,4-benzoquinone were converted into pyridinium enolate betaines by reaction with pyridine or 4,4′-bipyridine. The reaction conditions were applied to poly-(4-vinylpyridine) and a modified Merrifield resin to obtain functionalized polymeric materials. These were examined in thermogravimetric analyses. Reversible photocatalytic electron transfer reactions in the presence of proflavinium and EDTA as sensitizer and sacrificial donor, respectively, were examined. All monomeric and polymeric materials, except for one, proved to be active.
Enaminonitriles in Heterocyclic Synthesis: Novel Synthesis of 3-Aminopyrroles and Pyrrolo[3,2-d]pyrimidine Derivatives
Authors: Salaheldin Abdellatif M.
Published: August 2018

Several new 3-aminopyrrole derivatives have been synthesized from 3-substituted amino-2-phenylacrylonitriles using Thorpe-Ziegler cyclization. These substituted pyrroles are readily converted into 5H-pyrrolo[3,2-d]pyrimidines (9-deazapurines).
Water at High Dynamic Pressures and Temperatures
Authors: Nellis William J.
Published: August 2018

This paper is dedicated to Prof. G. Demazeau for his many contributions to the study of materials at high pressures and to the International Association for the Advancement of High-Pressure Science and Technology. This paper discusses two of Prof. Demazeau’s interests, water and high pressures. Experimental measurements are reviewed for water compressed dynamically from pressures of a few GPa up to 1.4 TPa and temperatures from 100 K up to 50000 K.
Modeling the Effect of Chemical Substitution and High Pressure on the Electronic Instabilities of the Ternary Intermetallics CeMIn5 (M = Co, Rh, Ir)
Authors: Alvarez Jose V. , Yndurain Felix
Published: August 2018

The phase diagram of the ternary intermetallics CeMIn5 (M = Co, Rh, In) presents new forms of competition and coexistence between magnetic and superconducting phases. We briefly review the experiments that have outlined the temperature-pressure phase diagram of these materials, emphasizing the phenomenon of reversible tuning. Expanding a recently proposed model for the coexistence of antiferromagnetism and superconductivity, we study the role of electronic doping on the ordering temperatures of these phases.
Solvothermal Processes for Nitride Synthesis: Examples of Li3GaN2 and Graphitic C3N4 Elaboration
Authors: Goglio Graziella , Denis Annaïg , Gaudin Etienne , Labrugère Christine , Foy Denis , Largeteau Alain
Published: August 2018

When precursors decompose or react in the presence of a solvent in a closed system at a temperature higher than the solvent’s boiling point the reaction is called a solvothermal process. This reaction can be carried out either in supercritical or subcritical conditions, in homogeneous or heterogeneous systems, pressure and temperature being both key parameters. As the main interest of such processes is the enhancement of chemical reactivity, solvothermal reactions have been widely involved for nitride elaboration. We report two examples relative to solvothermal syntheses of nitrides. The first one deals with the elaboration of Li3GaN2: this ionic nitride has been successfully synthesized, structurally characterized and tested as nutrient for the ammonothermal GaN crystal growth. The second one is related to the elaboration of a well-crystallized graphitic carbon nitride (g-C3N4) aimed to be developed as a precursor for conversion towards dense CNx phases.
Pressure Perturbation Calorimetric Studies on Phospholipid-Sterol Mixtures
Authors: Okoro Linus , Winter Roland
Published: August 2018

Sterols regulate biological processes and sustain the lateral structure of cellular membranes. The sterol cholesterol, its precursor lanosterol, the plant sterols stigmasterol and ergosterol as well as 7-dehydrocholesterol were added up to 36 mol-% to vesicles of the phospholipid 1,2-dipalmitoyl-snglycero- 3-phosphatidylcholine (DPPC). The aim of this study was to investigate the influence of the sterol side chain and ring structure on the volumetric properties of the lipid bilayer system by using pressure perturbation calorimetry (PPC), a relatively new and efficient technique, to study the thermal expansion coefficient and volumetric properties of biomolecules. The experiments were carried out in the temperature range from 10 to 85 °C, i. e., at temperatures below and above the chain-melting transition temperatures of the lipid mixtures. Additionally, corresponding differential scanning calorimetric (DSC) measurements were carried out.Whereas the conformational properties of the different sterols have a significant effect on the order parameter of the lipid acyl-chains, the thermodynamic parameters of these sterols are less influenced by the differential structural changes of the sterols. For lanosterol and stigmasterol, marked differences are found, however.
On the Thermal Expansion of Water and the Phase Behavior of Macromolecules in Aqueous Solution
Authors: Meersman Filip , Nies Erik , Heremans Karel
Published: August 2018

Water is crucial for the existence of life as we know it, and many have wondered what makes water so special. Here we point out the analogies between the pressure-temperature dependence of the isobaric thermal expansion of water (αp) and the pressure-temperature phase behavior of macromolecules in aqueous solutions. We suggest that αp could be the key to understand why water is to be the so-called ‘matrix of life’.
Kalium-Thio/Oxo-Vanadate(V) K3[VSxO4–x] (x = 1–4) und Na3[VSO3]: Synthese, Strukturchemie, Eigenschaften
Authors: Schnabel Simone , Röhr Caroline
Published: August 2018

The mixed potassium thio/oxo-orthovanadates(V) of the series K3[VSxO4−x] (x = 1, 2, 2.6, 3.4-4) and the sodium compound Na3[VSO3] have been prepared in evacuated silica ampoules at reaction temperatures of 450 to 600 °C starting from stoichiometric amounts of an alkali oxovanadate, the alkali sulfide and (where necessary) elemental vanadium and sulfur. The crystal structures (determined on the basis of X-ray single-crystal data) of the yellow compounds Na3[VSO3] (space group R3c, a = 863.3(3), c = 1234.7(3) pm, Z = 6, R1 = 0.0170) and K3[VSO3] (space group P21/m, a = 659.0(3), b = 589.5(3), c = 879.3(3) pm, β = 102.12(3)°, Z = 2, R1 = 0.0907) both contain isolated monothio-vanadate ions [VSO3]3−. The orange crystals of K3[VS2O2] (space group P21/m, a = 1056(2), b = 732.2(10), c = 1167(2) pm, β = 121.86(11)°, Z = 4, R1 = 0.0977) as well as the red phase K3[VS2.6O1.4] (space group P21/c, a = 1009.1(6), b = 681.2(4), c = 1190.1(8) pm, β = 93.55(1)°, Z = 4, R1 = 0.0929) also crystallize with new, singular, monoclinic structure types, which are nevertheless structurally related, as indicated by the similar lattice parameters. Starting from K3[VS4], a phase width up to the composition K3[VS3.4O0.6] (space group Pnma, a = 909.5(3), b = 1035.6(5), c = 895.6(6) pm, Z = 4, R1 = 0.0948) is observed in addition. Structure and bonding in this new series of potassium compounds are discussed and compared with those in the respective sodium phases, including aspects like anion geometry and dynamics (as observed by Raman spectroscopy), packing in the crystals, UV/Vis spectroscopy and FP-LAPW band structure calculations.
A One-pot Synthesis of Novel Functionalized (E)-β-Arylvinyl Bromides from anti-2,3-Dibromo-3-(4-carboxyphenyl)propanoic Acid
Authors: Kuang Chunxiang , Jiang Yubo , Yang Qing , Zhang Wensheng , Wen Yaolin
Published: August 2018

A facile one-pot synthesis of functionalized (E)-β -arylvinyl bromides bearing various 4-alkoxycarbonyl and 4-aryloxycarbonyl groups was achieved by debrominative decarboxylation of anti-2,3- dibromo-3-(4-carboxyphenyl)propanoic acid in the presence of AgOAc and subsequent esterification in the presence of dicyclohexyl carbodiimide and dimethylaminopyridine. This method gives (E)-β - arylvinyl bromides in high stereoselectivities and high yields, and tolerates aldehyde, ester, and nitro functional groups.
Screening of Medicinal Plant Methanol Extracts for the Synthesis of Gold Nanoparticles by Their Reducing Potential
Authors: Ramezani Neda , Ehsanfar Zeynab , Shamsa Fazel , Amin Gholamreza , Shahverdi Hamid R. , Esfahani Hamid R. Monsef , Shamsaie Ali , Bazaz Reza Dolatabadi , Shahverdi Ahmad Reza
Published: August 2018

Development of nontoxic, clean techniques for the synthesis of metal nanoparticles such as gold has attracted increasing attention in recent years. Although many reports have been published about the biogenesis of gold nanoparticles using several plant extracts such as Neem leaf broth (Azadirachta indica), the capacity of a large number of such extracts to form gold nanoparticles has yet to be elucidated. In this research a titrimetric assay was employed for preliminary evaluation of the reducing potential of different medicinal plant extracts. All the extracts were used separately for the synthesis of gold nanoparticles through the reduction of aqueous AuCl4
−. After the screening step, the methanol extracts of Eucalyptus camaldulensis and Pelargonium roseum were selected for further studies. The reducing ability of these extracts was significantly enhanced as compared to Neem leaf broth (Azadirachta indica) which was used as control sample. Transmission electron microscopy, energy-dispersive spectroscopy and visible absorption spectroscopy confirmed the reduction of gold ions to gold nanoparticles. The E. camaldulensis and P. roseum extracts produced gold nanoparticles in the size ranges of 1.25 - 17.5 and 2.5 - 27.5 nm with an average size of 5.5 and 7.5 nm, respectively.
A New pseudo-Alkaloid Taxane and a New Rearranged Taxane from the Needles of Taxus canadensis
Authors: Zhang Manli , Huo Changhong , Dong Mei , Li Ligeng , Sauriol Françoise , Shi Qingwen , Gu Yucheng , Kiyota Hiromasa , Cong Bin
Published: August 2018

A new taxane with an amino side chain on C-5 and a new 11(15→1)abeotaxane having a tetrahydrofuran ring along carbon atoms C-2, C-3, C-4, C-20 identified for the first time from the needles of the Canadian yew, Taxus canadensis. Their structures were characterized as 2α,7β ,9α,10β ,13-pentaacetoxy-11β -hydroxy-5α-(2´ -hydroxy,3'-N,N-dimethylamino-3´- phenyl)-propionyloxytaxa-4(20),12-diene (1) and 13α,20β -diacetoxy-5α,7β ,9α,10β -tetrahydroxy- 2α,20-epoxy-11(15→1)abeotaxa-11,15-diene (2) on the basis of 1D, 2D NMR spectroscopy and high-resolution FABMS analysis. Taxane 1 contains a rare C-12, C-13 double bond and a basic side chain, while taxane 2 bears a rare isopropenyl group at C-1.
Crystal Structure, NQR and DSC Studies of Tetrabromocadmates(II): [4-H2NC5H4NH]2CdBr4 · H2O and [2,3,5,6-(CH3)4C4N2H2]CdBr4
Authors: Hatano Naoko , Nakashima Michio , Horiuchi Keizo , Terao Hiromitsu , Ishihara Hideta
Published: August 2018

4-Aminopyridinium tetrabromocadmate(II) monohydrate (1) crystallizes in the orthorhombic space group Pbcm with a = 6.876(2), b = 14.089(2), and c = 18.845(2) Å , Z = 4, T = 296 K. In the crystal structure, a [CdBr4]2− anion, a 4-aminopyridinium cation, and a water molecule are alternately connected into chains by hydrogen bonds N-H···Br and O-H···Br. 2,3,5,6- Tetramethylpyrazinium tetrabromocadmate(II) (2) crystallizes in the orthorhombic space group P212121 with a = 14.640(12), b = 15.615(7), c = 6.686(5) Å , Z = 4, T = 296 K. In the crystal structure, a [CdBr4]2− anion and a 2,3,5,6-tetramethylpyrazinium cation are interconnected by bifurcated hydrogen bonds N-H· · ·2Br and form infinite chains. 81Br NQR spectra with three lines with an intensity ratio of 1 : 1 : 2 (77 K ≤ T ≤ ca. 325 K) and four lines with an intensity ratio of 1 : 1 : 1 : 1 (77 K ≤ T ≤ ca. 330 K) were observed for crystalline 1 and 2, respectively, which are consistent with the crystal structure data. DSC measurements showed the existence of thermal anomalies at high temperatures in both 1 and 2.
Comparison of Alkoxy-substituted 4,4´-Distyrylbiphenyls and the Corresponding 4,4´-Distyrylbenzenes
Authors: Meier Herbert , Lifka Thorsten , Oehlhof Annette
Published: August 2018

Configurationally highly pure (E,E)-4,4´-bis(styryl)biphenyls 2a - e were obtained by Siegrist reactions of 4,4´-dimethylbiphenyl 3 and alkoxy-substituted benzaldimines (4a - e). DSC measurements have indicated different crystalline modifications of these conjugated compounds. The stilbenoid chromophores of 2a - e are compared to the stilbenoid chromophores in the OPV series, which have a similar length of conjugation. The intense fluorescence and the high transparency in the visible region are promising properties for an application of the donor-substituted compounds 2a - e in twophoton absorption (TPA) techniques.
Synthesis of Dimethylphosphinyl-substituted α-Amino(aryl)methylphosphonic Acids and Their Esters
Authors: Zagraniarsky Yulian , Ivanova Bojidarka , Nikolov Karamfil , Varbanov Sabi , Cholakova Tsvetanka
Published: August 2018

Dimethylphosphinylmethylamine (1) and its aldimines 2 were used for the preparation of dimethyl and diethyl α-amino(aryl)methylphosphonates 3a - l via imine hydrophosphonylation and Kabachnik-Fields reaction. Their acid hydrolysis gave rise to the corresponding α-aminophosphonic acids 4a - e. Compounds 3 and 4 have two different phosphorus-containing groups - phosphonyl and dimethylphosphinyl - and might have interesting biological activity.
Reduction of a Heterocyclic Selenium(IV) Oxide LSeO by [Pd(COD)Cl2] – Crystal Structure of trans-[Pd(LSe)2Cl2]
Authors: Lozan Vasile , Kersting Berthold
Published: August 2018

The heterocyclic selenium(IV) oxide LSeO is reduced by [Pd(COD)Cl2] in MeCN solution to produce trans- [Pd(LSe)2Cl2] (2) (LSe = 2,3-dihydro-2-isopropyl-7-(Nisopropylcarbamoyl)- 1,2-benzisoselenazole-3-oxide). Complex 2 crystallizes in the triclinic space group P1̅ with a = 10.700(1), b = 10.871(1), c = 15.656(2) Å , α = 104.51(1), β = 94.59(1), γ = 95.25(1)◦, V = 1745.5(3) Å3, and Z = 2. The COD is oxidized to 5,6-epoxycyclooctene.
Flavanes from Dracaena cambodiana
Authors: Liu Jian , Dai Hao-Fu , Wu Jiao , Zeng Yan-Bo , Mei Wen-Li
Published: August 2018

Two new flavanes, (2S)-4′ ,7-dihydroxy-6,8-dimethylflavane (1), and (2S)-5,7-dihydroxy-4′-methoxy- 8-methylflavane (2), together with five known flavanes, (2S)-3′ ,7-dihydroxy-4′-methoxy-8- methylflavane (3), (2R)-4′,7-dihydroxy-8-methylflavane (4), (±)-3′,7-dihydroxy-4′-methoxyflavane (5), (±)-4′,7-dihydroxy-3′-methoxyflavane (6), and (2S)-4′,7-dihydroxyflavane (7), were isolated from the stem of Dracaena cambodiana. Their structures were determined by spectroscopic techniques (UV, IR, 1D and 2D NMR). Their antimicrobial activities were preliminarily examined by the filter paper disc agar diffusion method.