bluuebunny/crossref_metadata_2025 huggingface dataset:
Highly Efficient Synthesis of (Phosphinodihydrooxazole)- (1,5-cyclooctadiene) Iridium Complexes
Authors: Semeniuchenko Volodymyr , Khilya Volodymyr , Groth Ulrich
Published: February 2015

A highly efficient one-pot procedure for the synthesis of complexes of the type [Ir(COD)(Phox)]X, where Phox is a (chiral) phosphinooxazoline ligand, X = PF6 or B[(3,5-(CF3)2C6H3)]4 (BARF), is developed. Former reported syntheses demanded the isolation of pure ligands by column chromatography, but the ligands tend to adsorb irreversibly on silica. Moreover, the chromatography has to be performed with careful exclusion of air. The present method avoids this difficulties. The yields of the syntheses are comparable with those starting from the pure ligands. The method is also suitable for the preparation of complexes of the type [Rh(COD)(Phox)]BARF and [Rh(Phox)2]BARF.
Electron Transfer-induced Aromatization of 1,4-Dihydropyridines
Authors: Memarian Hamid R. , Ghazaie Marieh , Mehneh Somayeh Kakhki
Published: February 2015

A wide variety of 3,5-dicarboethoxy-1,4-dihydropyridines and 3,5-diacetyl-1,4-dihydropyridines are aromatized to the pyridine derivatives by 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) at room temperature and under microwave irradiation. An electron transfer-induced mechanism is proposed for this reaction which is influenced by the nature of the solvent, the nature of the substituents located on 3-, 4- and 5-positions of the 1,4-dihydropyridine ring, and the presence of oxygen or argon atmosphere.
5-Aminouracil as a Building Block in Heterocyclic Synthesis, Part II. One-pot Synthesis of Pyrido[3,2-d:6,5-dʹ]dipyrimidines under Microwave Irradiation without Catalyst
Authors: Shaker Raafat M. , Ameen Mohamed A. , Abdel Hameed Afaf M. , Elrady Mohamed Abd
Published: February 2015

An efficient and direct procedure for the synthesis of pyrido[3,2-d:6,5-dʹ]dipyrimidine derivatives under microwave-assisted conditions is been described. The structures of the products were characterized by elemental analyses, and their IR, 1H NMR, 13C NMR, and MS spectra.
Oxidation of Me3Bi with Formation of the Inorganic Polymer [Me2BiOMe]∞
Authors: Breunig Hans Joachim , Lork Enno , Nema Mihai-Gabriel
Published: February 2015

Single crystals of [Me2BiOMe]∞ (1) formed in the reaction of Me3Bi with oxygen in benzene have been analysed by X-ray crystallography (orthorhombic, Pnma, Z = 4, a = 8.254(2), b = 9.9020(10), c = 7.0430(10) Å, T = 173(2) K).
The Gas-phase Structure of the Hexasilsesquioxane Si6O9(OSiMe3)6
Authors: Wann Derek A. , Reilly Anthony M. , Rataboul Franck , Lickiss Paul D. , Rankin David W. H.
Published: February 2015

The equilibrium molecular structure of the hexasilsesquioxane, Si6O9(OSiMe3)6, has been determined in the gas phase by electron diffraction. With OSi-containing substituents on the cage silicon atoms, this molecule closely resembles the moiety that if reproduced in a periodic manner would yield a zeolite-type structure. Semi-empirical molecular-dynamics (SE-MD) calculations were used to give amplitudes of vibration, vibrational distance corrections (differences between interatomic distances in the equilibrium structure and the vibrationally averaged distances that are given directly by the diffraction data) and anharmonic constants. A number of different SE-MD methods were tested, and their results are compared. The inclusion of d-type orbitals in the SE-MD method is crucial for obtaining accurate vibrational quantities for Si6O9(OSiMe3)6, with the PM6 and MNDO/D methods both giving acceptable values
Size-controlled Synthesis of Gold Nanoparticles by Thermolysis of a Gold(I)-Sulfide Complex in the Presence of Alkylamines
Authors: Yamamoto Mari , Kashiwagi Yukiyasu , Nakamoto Masami
Published: February 2015

A size-controlled synthesis of gold nanoparticles has been developed by the thermolysis of AuCl(SMe2) in the presence of alkylamines at 120 °C. In the procedure, the key intermediate was [Au(NH2R)2]Cl, detected by electrospray ionization (ESI) mass spectrometry. This thermally unstable intermediate was reduced by alkylamines under mild conditions to produce alkylamine-capped gold nanoparticles. The average diameters of the gold nanoparticles could be regulated in a range from 4.3 to 6.1 nm by applying primary alkylamines with alkyl chains of different lengths. Larger gold nanoparticles with diameters from 10 to 22 nm were prepared by a combination of alkylamines and alkylcarboxylic acids with various lengths of the alkyl chains. The gold nanoparticles were characterized by transmission electron microscopy (TEM), UV/Vis absorption spectroscopy, powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), gas chromatography/mass spectroscopy (GC/MS), and thermogravimetric and differencial thermal analyses (TG/DTA)
Solvothermal Synthesis, Crystal Structure and Properties of [Mg(en)3][Sb4S7] – the First Thioantimonate(III) Containing a Main Group Metal Complex Cation as Structure Director
Authors: Quiroga-González Enrique , Näther Christian , Bensch Wolfgang
Published: February 2015

The new thioantimonate [Mg(en)3][Sb4S7] containing for the first time a [Mg(en)3]2+ cation as structure-directing unit was synthesized under solvothermal conditions applying elemental Mg, SbCl3, S and ethylenediamine. The compound crystallizes in the monoclinic space group P21/c with a = 9.9267(6), b = 14.254(1), c = 17.259(1) A° , β = 102.611(7)°, V = 2383.1(3) °A3, Z = 4. In the structure trigonal SbS3 pyramids are joined to form an Sb3S3 ring. The rings are connected through SbS3 units yielding an undulated chain anion running along [001]. Considering so-called secondary Sb-S bonds, a layer-like thioantimonate anion is formed. The [Mg(en)3]2+ cations are located between the layers. Relatively short S・ ・ ・H-N contacts suggest hydrogen bonding interactions between the cation and the [Sb4S7]2− anion. The compound starts to decompose at about 220 °C. The optical band gap of 2.35 eV is in agreement with the orange color of the crystals. In the Raman spectrum prominent Sb-S resonances are seen between 250 and 400 cm−1 which can be assigned to different Sb-S vibrations
Intermediate-valent Ce23Ru7Mg4 and RE23Ru7Mg4 (RE = La, Pr, Nd) with Pr23Ir7Mg4-type Structure
Authors: Linsinger Stefan , Eul Matthias , Hermes Wilfried , Hoffmann Rolf-Dieter , Pöttgen Rainer
Published: February 2015

The rare earth-rich magnesium compounds RE23Ru7Mg4 (RE = La, Ce, Pr, Nd) were synthesized from the elements in sealed tantalum ampoules in an induction furnace. They crystallize with the hexagonal non-centrosymmetric Pr23Ir7Mg4-type structure, space group P63mc. The structures of La23Ru6.88(1)Mg4 (a = 1017.7(4), c = 2286.5(5) pm, wR2 = 0.0277, 2708 F2, 71 variables), Ce23Ru7Mg4 (a = 993.5(3), c = 2243.9(8) pm, wR2 = 0.0573, 2268 F2, 70 variables), and Pr23Ru7Mg4 (a = 996.8(3), c = 2241.5(6) pm, wR2 = 0.0492, 2565 F2, 70 variables) have been refined from single-crystal diffractometer data. The structures are built up from complex threedimensional networks of edge- and corner-sharing RE6Ru trigonal prisms. Cavities within these networks are filled by slightly elongated Mg4 tetrahedra (311 - 315 pm in Pr23Ru7Mg4) and RE6 octahedra. The cerium compound has an a parameter which is even smaller than that of Nd23 Ru7Mg4, indicating intermediate-valent cerium. This was confirmed by magnetic susceptibility measurements. Ce23Ru7Mg4 shows an average, reduced magnetic moment of 2.01 μB/Ce atom. Pr23Ru7Mg4 contains stable trivalent praseodymium (3.64 μB/Pr atom)
Novel Synthetic Routes to s-Block Metal 2,5-Diphenylphospholides and Crystal Structures of the Bis(tetrahydrofuran) Complexes of the Potassium, Calcium, and Strontium Derivatives
Authors: Wimmer Katja , Birg Christin , Kretschmer Robert , Al-Shboul Tareq M.A. , Görls Helmar , Krieck Sven , Westerhausen Matthias
Published: February 2015

The reduction of 1,4-diphenyl-1,4-bis(diphenylphosphanyl)buta-1,3-diene (1) (1,4-diphenyl- NUPHOS) with potassium in THF yields bis(THF)potassium 2,5-diphenylphospholide (2) which crystallizes with a chain structure. The metathesis reaction of 2 with the iodides of calcium, strontium, and barium leads to the formation of [bis(THF)calcium bis(2,5-diphenylphospholide)] (3), [bis(THF)strontium bis(2,5-diphenylphospholide)] (4), and [bis(THF)barium bis(2,5-diphenylphospholide)] (5). The reaction of M{P(H)SiiPr3}2 with diphenylbutadiyne in THF also leads to the formation of the 2,5-diphenylphospholides of calcium (3), strontium (4), and barium (5). The molecular structures of 2 to 4 are discussed. The environment of the metal atoms is very similar in all these compounds: The metal atoms show an η5 coordination to the phospholide rings forming a bent sandwich complex. The open coordination site is occupied by two THF molecules
Synthesis and Solid-state Structures of 1,3- and 1,4-Bis(diethylgallyl) benzene
Authors: Izundu Joseph , Jutzi Peter , Neumann Beate , Sielemann Henning , Stammler Hans-Georg
Published: February 2015

The compounds 1,3-bis(diethylgallyl)benzene (3) and 1,4- bis(diethylgallyl)benzene (6) were prepared by reaction of the corresponding chloromercuriobenzenes with an excess of triethylgallium by applying pressure and higher temperatures. These compounds very easily undergo redistribution reactions in solution and in the solid state. Extremely air-sensitive crystals suitable for an X-ray crystal structure analysis were obtained from triethylgallium as solvent. The structural studies revealed the presence of tetra-coordinated carbon and gallium atoms in symmetric aryl-diethylgallyl bridging units. The coordination behavior of 3 and 6 in the solid state is quite different from that of the corresponding methyl-substituted compounds
Synthesis, Structure and Bonding in Triorganogermyl-alanes and Triphenylgermyl-aluminates
Authors: Habereder Tassilo , Nöth Heinrich , Suter Max
Published: February 2015

Triphenylgermyl-lithium in diethyl ether/THF did not react with Al2Me6 to form [(Ph3Ge)AlMe3]- Li(THF)n. Addition of TMEDA to this solution yielded crystalline Ph3GeLi(THF)TMEDA. The reaction of Ph3GeLi in diethyl ether/hexane solution with H3Al-NMe3 in diethyl ether/THF generated [Ph3GeAlH3]Li(THF)4 while the reaction with Me2AlCl led to Ph3GeAlMe2(OEt2) and the trigermyl-aluminate [(Ph3Ge)3AlMe]Li. The analogous aluminate [(Ph3Ge)3AlH]Li(THF)3 was obtained by reacting LiGePh3 with AlH2Cl(OEt2) in the presence of THF. It was expected that the bulky bis(tetramethylpiperidino)chloroalane would react with Ph3GeLi to give the germyl-alane tmp2AlGePh3 which was observed when only diethyl ether was used as a solvent, but in an Et2O/toluene mixture only Ph8Ge3 could be isolated. Increasing the steric requirement of the germyllithium compound by using the bulky (tBu3Si)Me2Ge group instead of the Ph3Ge group led to a straightforward reaction generating the first structurally characterized germyl-alane (tBu3Si)Me2Ge- Al(tmp)2 with a planar tri-coordinated Al center. The X-ray structure determinations showed that the germyl-aluminates have shorter Ge-Al bonds than the germyl-alane inspite of the lower coordination number
Structure and Reactivity of (η5-Cyclopentadienyl)(triphenylphosphine)- (undecamethylcyclohexasilyl)nickel(II)-Hexane (2/1) Structure and Reactivity of (η5-Cyclopentadienyl)(triphenylphosphine)- (undecamethylcyclohexasilyl)nickel(II)-Hexane (2/1)
Authors: Hoffmann Florian , Böhme Uwe , Roewer Gerhard
Published: February 2015

The nickel cyclohexasilyl complex CpNi(PPh3)Si6Me11 was synthesized from nickelocene, triphenylphosphine, and undecamethylcyclohexasilyl potassium and was fully characterized. It shows a relationship between its Si-Si bond lengths and its reactivity towards oxygen. The cleavage of one cyclopentadienyl ligand from nickelocene by silyl anions in the presence of additional ligands opens a promising new pathway to nickel silyl complexes of the type CpNi(L)-SiR3
Dinuclear Gold Complexes of Two Simple but Underutilized Dicarbanionic Ligand Types
Authors: Coetzee Karolien , Strasser Christoph E. , Cronje Stephanie , Raubenheimer Helgard G.
Published: February 2015

Both mono- and bisylide zwitterionic complexes of gold(I), [(C6F5){PhCH(PPh3)}Au] (4), [(C6F5)2(C6H4-p){CH(PPh3)}2Au5] (5) and [(C6F5)2(C6H4-m){CH(PPh3)}2Au2] (6) were prepared by THT substitution in [C6F5(THT)Au] (THT = tetrahydrothiophene) using deprotonated mono- and bis-phosphonium salts. Lithiation of 4,4'-dibromo-2,3,5,6,2',3',5',6'-octafluoro-1,1_- biphenyl and transmetallation with [Cl(Ph3P)Au] produced a dinuclear gold complex of octafluorosubstituted biphenyl [[(PPh3)2(C6F4-C6F4)2Au2]] (8)
Trinuclear Mixed-valent Gold Complexes Derived from 2-C6F4PPh2: Phosphine Oxide Complexes of Gold(III) and an ortho-Metallated Complex of Gold(I)
Authors: Bennett Martin A. , Mirzadeh Nedaossadat , Privér Steven H. , Wagler Jörg , Bhargava Suresh K.
Published: February 2015

Crystals of two mixed-valent gold complexes [(O2NO)AuI(μ-2-C6F4PPh2)AuIII{κ2-2-C6- F4P(O)Ph2}(μ-2-C6F4PPh2)AuI(ONO2)] (14) and [(O2NO)AuI(μ-2-C6F4PPh2)AuIII{κ3-2-C6F4- P(O)Ph(C6H4)}(μ-2-C6F4PPh2)AuI] (15) have been obtained from the reaction of the digold(I,III) complex [ClAuI(μ-2-C6F4PPh2)(κ2-2-C6F4PPh2)AuIIICl] (5) with, respectively, a small and a large excess of silver nitrate. Both complexes contain three, approximately collinear metal atoms, the central gold(III) atom being planar-coordinated by a chelate (O,C)-phosphine oxide formed by oxidation of 2-C6F4PPh2 and the carbon atoms of two bridging 2-C6F4PPh2 groups. In 14 each of the terminal gold(I) atoms is coordinated by a monodentate nitrate ion and the phosphorus atom of μ-2-C6F4PPh2, whereas in 15 the nitrate ion on one of the gold(I) atoms of 14 has been replaced by the carbon atom of a bridging C6H4 group derived by Ag+-promoted cyclometallation of a phenyl group on the neighbouring phosphine oxide
IR Spectroscopy of Two Polymorphs of Copper(I) Thiocyanate and of Complexes ofCopper(I) Thiocyanate with Thiourea and Ethylenethiourea
Authors: Bowmaker Graham A. , Hanna John V.
Published: February 2015

Syntheses and infrared spectroscopic studies are reported for two different polymorphs of copper( I) thiocyanate and for adducts of copper(I) thiocyanate with thiourea (‘tu’) and ethylenethiourea (‘etu’ = imidazolidine-2-thione; (CH2NH)2CS)). These include the previously reported complex CuSCN/etu (1 : 2), which has a trigonal monomeric structure, and CuSCN/etu (1 : 1), which has a three-dimensional polymeric structure. A mechanochemical/infrared study of the CuSCN: tu (1 : 2) system showed that no 1 : 2 complex exists in this case, the product being a mixture of a 1 : 3 complex and a novel 1 : 0.5 complex. The latter complex was prepared both mechanochemically and from solution, and characterized by infrared and solid-state 65Cu broadline NMR spectroscopy. Diagnostic ligand and metal-ligand bands in the IR and far-IR spectra are assigned for both polymorphs of CuSCN and for all of the complexes studied and are discussed in relation to the structures of the complexes
Gold(I) Complexes Bearing P∩N-Ligands: An Unprecedented Twelve-membered Ring Structure Stabilized by Aurophilic Interactions
Authors: Monkowius Uwe , Zabel Manfred , Fleck Michel , Yersin Hartmut
Published: February 2015

The P∩N-ligands Ph2Pqn, 1, Ph2 Piqn, 2, Ph2 Ppym, 3, and the As∩N-ligands Ph2Asqn, 4, Ph2Asiqn, 5, (Ph = phenyl, qn = 8-quinoline, iqn = 1-isoquinoline, pym = 2-pyrimidine) have been synthesized, the ligands 2 and 5 for the first time. Their ligand properties were probed by the synthesis of gold(I) complexes. Reaction with (tht)AuCl (tht = tetrahydrothiophene) yielded the chlorogold complexes Ph2RP-Au-Cl (R = qn, 6; iqn, 7; pym, 8) and Ph2RAs-Au-Cl (R = qn, 9; iqn, 10) in high yields. Further treatment of 7 and 8 with one equivalent of AgBF4 provided the complexes [(Ph2Piqn)Au]BF4, 11, [(Ph2Ppym)Au]BF4, 12, and [(Ph2Piqn)Au(tht)]BF4, 14. For comparison, the previously reported complex [(Ph2Ppy)Au]BF4 (py = pyridine), 13, was re-investigated. The compounds were characterized by elemental analyses, mass spectrometry and NMR spectroscopy. In addition, the solid-state structures of 2, 3, 6, 7, 9 - 14 have been determined by X-ray crystallography. The chloro-gold compounds crystallize in the common rod-like structure known from R3EAuCl (R = aryl, E = P, As) complexes without further aggregation via aurophilic interactions. In all cases the phosphine acts as a monodentate ligand. In the solid state compounds 11 - 13 feature an unprecedented cyclic trinuclear aggregation pattern, in which the Au(I) atoms are linearly coordinated by the bridging phosphine ligands forming a cyclic (P-Au-N)3 arrangement. The resulting twelvemembered ring is further stabilized by Au · · · Au interactions. Due to the presence of these Au · · · Au contacts, 11 - 13 are emissive in the solid state but not in solution
Selective Si–O–Si Bond Cleavage as Synthetic Access to Functionalized, Hydrolysis-stable Zinc Silanolates
Authors: Däschlein Christian , Strohmann Carsten
Published: February 2015

The selective cleavage of the strong and poorly reactive Si-O-Si bond in functionalized siloxanes under mild conditions is a decisive task for modern synthetic chemistry. Simple treatment of the aminomethyl-functionalized disiloxanes 1, 6, (R,R)-7 and 8 ([R2(CH2NR')SiO]2, R =Me or Ph, NR'= NC5H10, NC5H8(CH3)2 or NC4H7(CH3)) with zinc(II) bromide and zinc(II) chloride, respectively, results in the formation of highly hydrolysis-stable, molecular zinc silanolates which were long time supposed to be unstable in the presence of water. Both, the selective cleavage of the Si-O-Si bond as well as the formation of the molecular zinc silanolates are independent of the substituents at silicon, the used zinc(II) salt or the aminomethyl side arm. Detailed structural studies showed that zwitterionic interactions are the reason for the high stability towards hydrolysis of the formed zinc silanolates 9, 10, (R,R)-11 and 12. NMR studies are indicative of the same structure of these molecular systems in solution as in the solid state
Tin-containing Indane and Tetralin Derivatives
Authors: Zarl Elisabeth , Albering Jörg H. , Fischer Roland C. , Flock Michaela , Genser Dominik , Seibt Barbara , Uhlig Frank
Published: February 2015

The preparation of tin-containing indane and tetralin derivatives via two different reaction pathways is reported. The first route is the reaction of dichlorostannanes or bis(fluoroalkylsulfonyl)stannanes withα,α'-di(chloromagnesium)xylene. The second reaction is the direct coupling of chlorostannanes and α,α'-dichloroxylene which always yields a mixture of tin-containing indanes and tetralins. The separation of these compounds can easily be achieved by fractional crystallization. By these simple and effective routes the first 2,3-distannatetralins were synthesized
Enantioselective Hydrosilylation with a Chiral N-Heterocyclic Carbene Complex of Rhodium(I) [1]
Authors: Zinner Sandra C. , Zhang-Preße Mei , Herrmann Wolfgang A. , Kühn Fritz E.
Published: February 2015

Both enantiomers of the chiral rhodium-NHC complex [(4X, 5X)-1,3-bis[2,6-diisopropyl-phenyl]- 4,5-ditert-butylimidazolidine-2-ylidene][1,5-cyclooctadiene]-iodo-rhodium(I) with X = R, S were applied as catalysts for the asymmetric hydrosilylation of prochiral ketones. The influence of employed solvent, substrate, silane, and catalyst enantiomer on the catalytic activity and the enantioselectivity of the desired product was investigated
Structure and Properties of Non-classical Polymers. XV. 1D Polymers Possessing Two Bands with Ferromagnetically Coupled Electrons
Authors: Tyutyulkov Nikolai , Drebov Nedko , Müllen Klaus , Dietz Fritz
Published: February 2015

The energy spectra and magnetic properties of a new class of non-classical (non-Kekulé) 1D polymers, having two bands with magnetically coupled electrons, have been investigated by manyelectron band theory
Thermolysereaktionen der donorfreien Silanimine tBu2Si=N-SiRtBu2 (R = tBu, Ph) / Thermolysis Reactions of Donor-free Silanimines tBu2Si=N-SiRtBu2 (R = tBu, Ph)
Authors: Lerner Hans-Wolfram , Sänger Inge , Bolte Michael , Wagner Matthias
Published: February 2015

The donor-free silanimines tBu2Si=N-SiRtBu2 (R = tBu, Ph), which are prepared from tBu2ClSiN3 and NaSiRtBu2 at −78 ◦C inBu2O, decompose in benzene at room temperature with the formation of isobutene. Products of ene reactions of isobutene and tBu2Si=N-SiRtBu2 (R = tBu, Ph) are formed. X-Ray quality crystals of H2C=C(CH2SitBu2-NH-SiPhtBu2)2 (monoclinic, space group C2/c, Z = 4) were grown from a benzene solution at ambient temperature, whereas single crystals of H2C=C(CH2SitBu2-NH-SitBu3)2 (monoclinic, space group P21, Z = 2) were obtained by recrystallization from THF
Two New Clerodane Diterpenes from Dodonaea viscosa
Authors: Huang Zheng , Jiang Meng-Yuan , Zhou Zhong-Yu , Xu Di
Published: February 2015

Two new clerodane diterpenes 4 and 3, along with four known constituents, including neocleroda- 3,13-diene-15,16-olide-18-oic acid (1), stictic acid (2), hautriwaic acid (5), and 15,16-epoxy-19- hydroxy-1,3,13(16),14-clerodatetraen-18-oic acid (6), were isolated from stems and leaves of Dodonaea viscosa. Their structures were elucidated by spectroscopic methods, including one- and twodimensional NMR experiments (COSY, HMBC, HMQC, and ROESY)
Reaction of a Zwitterionic Pyridinium Ylide with N,N-Dimethylaniline
Authors: Sweidan Kamal , Kuhn Norbert , Maichle-Mößmer Cäcilia , Steimann Manfred
Published: February 2015

1,3-Dimethyl-2,4,6-trioxo-5-pyridinomethyl-1,3-perhydrodiazin- 5-ylpyridinium ylide (3) reacts with N,N-dimethylaniline to give 5-((1,3-dimethyl-2,4,6-trioxo-hexahydropyrimidin- 5-yl)methyl)-5-(4-(dimethylamino)benzyl)-1,3- dimethylpyrimidine- 2,4,6(1H3H5H)-trione (6) in good yield. The crystal structure of 6 is reported
Fabrication and Characterization of Antibacterial-active Multilayer Films Based on Keggin Polyoxometalates and Methylene Blue
Authors: Chen Dan , Peng Jun , Pang Haijun , Zhang Pengpeng , Chen Yuan , Chen Changyun , Ma Huiyuan
Published: February 2015

Two kinds of multilayer films based on Keggin polyoxometalates α-[SiW12O40]4−/α- [PMo12O40]3− and methylene blue have been prepared via the layer-by-layer (LBL) self-assembly technique. The multilayer films were characterized by UV/Vis spectra, atomic force microscopy (AFM) and X-ray photoelectron spectra (XPS). The cyclic voltammetry (CV) measurements have demonstrated that the electrochemical properties of POMs are maintained in the LBL films. The antibacterial activity of the LBL films has also been investigated, which shows a distinct antibacterial effect against Escherichia coli.
Phytochemical Studies on Alstonia scholaris
Authors: Sultana Nighat , Saleem Muhammad
Published: February 2015

Reinvestigation of the flowers of Alstonia scholaris of Pakistan origin have resulted in the isolation of three new triterpenoids, two of the ursane type, 3β -acetate-24-nor-urs-4,12-diene ester triterpene (1) and 3β -hydroxy-24-nor-urs-4,12,28-triene triterpene (2), and one of the oleanane type, 3,28-β - diacetoxy-5-olea-triterpene (3), together with two known triterpenes,α-amyrin acetate (4) and ursolic acid (5). This is the first report of the isolation of 4 and 5 from the flower part of this species. The structures of 1 - 5 were elucidated with the aid of extensive NMR-spectroscopic studies.
Sind Metalloprotonencryptanden möglich? – DFT-Studie zur Protonenaffinität von [2.2.2]-analogen Metallocryptanden / Can Metallocryptands act as Proton Cages? – DFT Study of Proton Affinity in [2.2.2]-analogousMetallocryptands Sind Metalloprotonencryptanden m¨oglich? – DFT-Studie zur Protonenaffinit¨at von [2.2.2]-analogen Metallocryptanden
Authors: Puchta Ralph , Scheurer Andreas
Published: February 2015

Based on density functional calculations (RB3LYP/LANL2DZp) the bicyclic metallocryptand [Pd3(L2)2] [(L2)3−: 1,1´ ,1´´-nitrilotris(5,5-dimethylhexane-2,4-dione trianion)] shows the same high gas-phase basicity (−257.1 kcal mol−1) as Lehn’s [2.2.2] cryptand (−254.4 kcal mol−1). This illustrates that the concept of metallotopomers adopted by Saalfrank et al. can be applied to design proton sponges as well as proton cryptands by metallosupramolecular coordination chemistry. The slightly higher gas-phase proton affinity of [Pd3(L2)2] compared to [2.2.2] can be attributed to the smaller cavity in the metallotopomer.
A Novel Five-coordinate Mn Complex with a Redox-active SNNNS Ligand System
Authors: Dürr Katharina , Yalalov Denis A. , Heinemann Frank W. , Tsogoeva Svetlana B. , Ivanović-Burmazović Ivana
Published: February 2015

Synthesis and characterization of a manganese complex of a new redox-active diaminocyclohexane derivative of a thiourea-based ligand with SNNNS donor atom set is reported. The molecular structure of the complex exhibits a pentadentate SNNNS ligand coordinated in the neutral form to the Mn(II) center. The coordination around the central metal is best described as distorted trigonal bipyramidal with the pyridine nitrogen and the two sulfur atoms being in the equatorial plane and the remaining two nitrogen donors occupying the apical positions of the bipyramid. Cyclic voltammetry in DMSO shows the MnII/MnIII redox couple with the oxidation peak at −0.199 V and the reduction peak at −0.587 V vs. Fc/Fc+ (scan rate 0.5 V s−1). The ligand itself possesses redox activity and exhibits prominent oxidation and reduction peaks at −1.194 and −1.481 V vs. Fc/Fc+, respectively. The results of electrochemical experiments under oxygen atmosphere suggest that upon reaction with electrochemically generated superoxide the redox-active ligand is modified causing decomposition of the complex.
Supramolecular Architectures of Copper(II) Perchlorate Complexes of cis,trans-1,3,5-Triaminocyclohexane Assembled Exploiting the Delicate Balance Between Weak and Strong Interactions
Authors: Ochoa M. Nieves Corella , Cooper Geoffrey J. T. , Newton Graham N. , Long De-Liang , Seeber Georg , Cronin Leroy
Published: February 2015

The complexation of copper(II) perchlorate with cis,trans-1,3,5-triamino-cyclohexane (transtachH) yields four related mononuclear complexes, [Cu(trans-tachH)2](ClO4)4・(H2O) (1), [Cu(transtachH) 2](ClO4)4・2MeOH (2), [Cu(trans-tachH)2(ClO4)](ClO4)3 (3) and [Cu(trans-tach)(transtachH)( ClO4)2](ClO4)・H2O (4). These complexes only differ with respect to ligand protonation, solvent coordination / content, and counterion binding, yet these small differences manifest as vast differences in the supramolecular structures, and we also show that certain crystalline phases of these four compounds persist for different lengths of time in the mother liquor.
Enantioselective Biocatalytic Reduction of Non-protected Hydroxyacetophenones
Authors: Neupert Adrian , Ress Tina , Wittmann Jürgen , Hummel Werner , Gröger Harald
Published: February 2015

Direct enantioselective reduction of 2´-, 3´- and 4´ -hydroxyacetophenone without protection of the hydroxy moiety was carried out in the presence of (R)- and (S)-alcohol dehydrogenases as biocatalysts. Whereas reduction of 2´-hydroxyacetophenone gave only low to medium conversions, reduction of 3´- and 4´ -hydroxyacetophenone proceeded efficiently leading to the resulting 1-(3- hydroxyphenyl)ethan-1-ol and 1-(4-hydroxyphenyl)ethan-1-ol with high conversion (up to > 95 %) and excellent enantioselectivity (up to > 99% ee).
Vibrational Spectra of Phenylphosphonic and Phenylthiophosphonic Acid and their Complete Assignment
Authors: Förner Wolfgang , Badawi Hassan M.
Published: February 2015

The structures and conformational stabilities of phenylphosphonic acid and phenylthiophosphonic acid were investigated using calculations mostly at DFT/6-311G** and ab initio MP2/6-311G** level. From the calculations the molecules were predicted to exist in a conformational equilibrium consisting of two conformers which as enantiomers have the same energy, but rather unexpected dihedral angles XPCC (X being O or S) which are not equal to zero. The antisymmetric potential function for the internal rotation was determined for each one of the molecules. In these functions the conformers with zero dihedral angles appear to be stable minima (also optimization converges to this), but the vibrational frequency for the torsion turned out to be imaginary, indicating that they are maxima with respect to this symmetry coordinate. Only optimization without any restrictions and starting from a non-zero torsional angle converged to a real minimum with such a geometry (“non-planar”). For that minimum structure infrared and Raman spectra were calculated, and those for phenylphosphonic acid were compared to experimental data, showing satisfactory agreement. This gives confidence to present the spectra of phenylthiophosphonic acid as a prediction. The rather low intensity of the OH bands in the experimental infrared spectrum (as compared to normal organic acids) indicates rather weak hydrogen bonding. Normal coordinate calculations were carried out, and potential energy distributions were calculated for the molecules in the non (near)-planar conformations providing a complete assignment of the vibrational modes to atomic motions in the molecules. From the rather low rotational barriers we conclude, in agreement with results from the literature (for other P=O compounds) based on localized orbitals that conjugation effects are absent - or at least negligible - as compared to electrostatic and steric ones in determining the structures of the stable conformers in the phenyl derivatives. The P=O (and also the P=S) bond is highly polarized according to our analysis of Mulliken populations. The polarization turned out to be smaller in the thiophosphonic acid due to the smaller electronegativity of sulfur as compared to oxygen.
Understanding Selectivities in Ligand-free Oxidative Cyclizations of 1,5- and 1,6-Dienes with RuO4 from Density Functional Theory
Authors: di Dio Philipp J. , Zahn Stefan , Stark Christian B.W. , Kirchner Barbara
Published: February 2015

Quantum-chemical calculations using density functional theory were carried out to investigate the mechanism of the oxidative cyclization of 1,5- and 1,6-dienes with ruthenium tetroxide. Current experimental results show different selectivities for the formation of tetrahydrofuran and tetrahydropyran derivatives. Our theoretical data correctly reproduce the experimental selectivities. Transition structures for the first [3+2]-cycloaddition of RuO4 with ethene and for the second [3+2]- cycloaddition with two ethene molecules, 1,5-hexadiene, and 1,6-heptadiene were calculated. For the formation of tetrahydrofuran and tetrahydropyran derivatives we observed two reaction pathways. The transition structure for the formation of cis-tetrahydrofuran derivatives was found to be more stable than the trans-tetrahydrofuran-forming transition structure by about 40 kJ mol−1. By comparison to the reaction with two ethene molecules it was shown that the linking alkyl chain causes the energy gap between stereoisomers by a directing influence. In the tetrahydropyran reaction the transtetrahydropyran- forming transition structure was less than 4 kJ mol−1 more stable than the transition structure leading to the cis-tetrahydropyran. The obtained geometries showed that for tetrahydropyrans the energy gap between stereoisomers is not caused by the linking alkyl chain.
Push-Pull-Allenes: The Influences of Substituents on the Activation of Allenes by Biomimetic Zinc Complexes
Authors: Burkhard O. Jahn , Eger Wilhelm A. , Anders Ernst
Published: February 2015

The influence of substituents at the allene skeleton on the rate-determining step of the reaction with nucleophiles catalyzed by biomimetic zinc complexes was investigated with quantum chemical (especially DFT) methods. Additional examinations were applied to derivatives of the zinc hydroxide complex modeled in analogy to the catalytic center of carbonic anhydrase. Especially suitable substituents in the allene moiety can lead to a significant lowering of the activation barrier. Further we demonstrate that by the application of this principle of a bioanalogous enhancement of reactivity other nucleophiles instead of the biological substrate can also be reactants in completely closed catalytic reaction cycles.
First Total Synthesis of a Fluorinated Calystegin
Authors: Csuk René , Prell Erik , Reißmann Stefan , Korb Claudia
Published: February 2015

A straightforward chiral pool synthesis for the first fluorinated calystegin is described. Key steps of this synthesis include an ultrasound-assisted Zn-mediated tandem ring opening reaction followed by a Grubbs’ catalyst-mediated ring closure metathesis reaction. The target compound is a selective and competitive inhibitor for a β -glycosidase.
H3PW12O40: An Efficient and Recyclable Heterogeneous Catalyst for the Selective Synthesis of 2-Aryl-5,6-dihydro-4H-1,3-oxazines and 2-Aryl-1,4,5,6-tetrahydropyrimidines
Authors: Mohammadpoor-Baltork Iraj , Moghadam Majid , Tangestaninejad Shahram , Mirkhani Valiollah , Eskandari Zohre
Published: February 2015

An environmentally friendly and highly efficient procedure has been developed for the selective synthesis of 2-aryl-5,6-dihydro-4H-1,3-oxazines and 2-aryl-1,4,5,6-tetrahydropyrimidines by cyclocondensation of arylnitriles with 3-amino-1-propanol and 1,3-diaminopropane in the presence of catalytic amounts of H3PW12O40 under thermal conditions and MW irradiation. Under the same reaction conditions, dicyanobenzenes are transformed to their corresponding mono-oxazines and monotetrahydropyrimidines with excellent chemoselectivity. These reactions are simple and clean, giving the products in high yields and high purity. The catalyst can be easily recovered after the reaction and reused efficiently in subsequent runs.
Synthesis of 3,4-Dihydropyrimidin-2(1H)-one-5-carboxamides
Authors: Soleymani Mousa , Memarian Hamid Reza
Published: February 2015

The synthesis of various dihydropyrimidinone derivatives bearing carbamoyl moieties in 5-position under reflux conditions and microwave irradiation is described. An efficient three-component Biginelli reaction using catalytic amounts of zirconium(IV) chloride as an efficient catalyst leads to the formation of these compounds.
New Calcium Hydride Halides with Familiar Structures. Syntheses and Crystal Structures of Ca7H12Cl2 and Ca2H3Br
Authors: Reckeweg Olaf , DiSalvo Francis J.
Published: February 2015

Single crystals of Ca7H12Cl2 and Ca2H3Br were obtained by reacting stoichiometric amounts of CaH2 and CaX2 (X = Cl, Br) at 1300 K in the presence of surplus Ca metal for 13 h in silicajacketed Nb ampoules. The crystal structures of the new compounds were determined by means of single-crystal X-ray diffraction. Ca7H12Cl2 crystallizes isotypical to Ba7Cl2F12 and Sr7H12Cl2 in the hexagonal space group P¯6 (no. 174) with the lattice parameters a = 936.51(8), c = 368.65(2) pm, while Ca2H3Br crystallizes in a stuffed anti-CdI2 structure isotypical to Ba2H3Cl and therefore adopts the space group P¯3m1 (no. 164) with the lattice parameters a = 391.37(6) and c = 697.04(13) pm. The structural results are corroborated by EUTAX calculations on the title compounds and the comparison of these results to those for CaH2, CaX2 and CaHX (X = Cl, Br). Similar calculations on the hypothetical compound “Ca7H12Br2” give a possible explanation for the preferred formation of the compound Ca2H3Br.
Condensed [OPr4]10+ and Discrete [AsO3]3–Ψ1-Tetrahedra in Pr5O4Cl[AsO3]2
Authors: Ben Yahia Hamdi , Villesuzanne Antoine , Rodewald Ute Ch. , Schleid Thomas , Pöttgen Rainer
Published: February 2015

The oxide chloride arsenite Pr5O4Cl[AsO3]2 was obtained as green crystals as a by-product of the synthesis of PrOTAs oxide arsenides (T = late transition metal), starting from Pr6O11, a transition metal oxide, arsenic, and an NaCl/KCl flux. Pr5O4Cl[AsO3]2 crystallizes with the monoclinic Nd5O4Cl[AsO3]2-type structure, space group C2/m. The structure was refined from single-crystal diffractometer data: a = 12.4943(15), b = 5.6884(13) c = 9.0776(19) Å , β = 116.61(1)°, R(F) = 0.0264, wR(F2) = 0.0509, 542 F2 values, and 52 variables. It is built up from corrugated layers of edge- and corner-sharing [OPr4]10+ tetrahedra, which are connected via chloride anions. The space between the layers is filled by these Cl− and discrete arsenite anions [AsO3]3− with lone pairs pointing towards each other. The network of condensed [OPr4]10+ tetrahedra is compared with the different arrays in the oxide pnictides α-PrOZnP, and in β -PrOZnP. Arsenic lone pair energy bands, main interactions, and the spatial distribution were identified precisely using density functional theory (DFT). Among the three crystallographically different sites for praseodymium, one was found non-magnetic in these calculations.
Synthese und Cyclisierung von Boryl- und Silylhydrazonen / Synthesis and Cyclisation of Boryl- and Silylhydrazones
Authors: Görth Martin , Schneider Ute , Ott Holger , Schulzke Carola , Stalke Dietmar , Klingebiel Uwe
Published: February 2015

Reactions of the lithium salts of the tert-butylmethylhydrazones Me3C(Me)C=N-NLiR, (R = H, Me, CMe3) with fluorosilanes and -boranes in a molar ratio 1 : 1 gave the silyl- (1 - 3, 5, 6) and borylhydrazones (4, 8) Me3 C(Me)C=N-N(R)Rʹ; 1: R = H, Rʹ = SiFMe2 ; 2: R = H, Rʹ = SiMe2CMe3; 3: R = H, Rʹ = SiF(CMe3 )2; 4: R = H, Rʹ = BFN(SiMe3)2; 5: R = Me3 C, Rʹ = SiF2CMe3; 6: R = Me3C, Rʹ = F2SiC(SiMe3)3; 8: R = Me3C, Rʹ = BFN(SiMe3)2. The lithiated hydrazone Me2C=N-NH(Me) reacted with F3SiC(SiMe3)3 to give the silylhydrazone Me2C=N- NHSiF2C(SiMe3)3, 7. Because of the fluoro functionality of 1 and 4, the bis-hydrazonylsilane 9 and the bis- and tris-hydrazonylboranes 10 and 11 could be synthesised, (Me3C(Me)C=N-NH)2R; 9: R = SiMe2 , 10: R = BN(SiMe3)2; 11: (Me3C(Me)C=N-NH)3B. Starting from 2 and its lithium salt, secondary substitutions are possible. Bis(silyl)- and silyl(boryl)hydrazones are formed (12 - 15); Me3C(Me)C=N(R) (SiMe2CMe3) 12: R = SiFMe2; 13: R = SiF(CMe3)2; 14: R = SiF2CMe3; 15: R = BFN(SiMe3 )2. Ring closure occurs in the reaction of dilithiated Me2C=N- NHCMe3 with F2Si(CHMe2)2. The 1,2-diaza-3-sila-5-cyclopentene 16 is isolated. The fluorofunctional silyl-hydrazones 7, 12, and 13 cyclise in reactions with t-BuLi to give 1,2-diaza-3-sila-5- cyclopentenes 17 - 20; RN(N=CRʹ-CH2)Rʺ; 17: R =Me,Rʹ = Me3C, Rʺ = SiFC(SiMe3)3; 18: R = Me3C, Rʹ = SiMe2CMe3, Rʺ = SiMe2; 19: R =Me3C, Rʹ = SiMe2CMe3, Rʺ = Si(CMe3)2. A 1,2- diaza-3-bora-5-cyclopentene 20 is the result of the reaction of 8 with t-BuLi: Me3CN(N=CCMe3- CH2)BN(SiMe3)2. The H-acidic methylene group of the five-membered ring in 20 can be lithiated with n-BuLi and substituted with fluorosilanes. Starting from 16 and 20, the silyl-substituted rings Me3CN(N=CMe-CHR)Si(CHMe2)2 21 - 23 and 25 are obtained; 21: R = SiMe3; 22: R = SiF2C(SiMe3)3; 23: R = SiF3; 25: Me3CN[N=CC(Me)3CHSiMe3]BN(SiMe3)2. Using SiF4 as fluorosilane, the main product is the difluorosilane containing two rings; F2Si[CHC(Me)=N-NCMe3- Si(CHMe2)2]2. The methine group in 4-position of the silyl-substituted rings is also acidic and reacts with n-BuLi to give lithium salts which react with aminodifluoroboranes giving the ring compounds Me3CN[N=C(CMe3)C(SiMe2R)(FBNRʹ SiMe3)]SiMe2 26 - 28; 26: R = Me, Rʹ = CMe3; 27: R = F, Rʹ = CMe3 ; 28: R = F, Rʹ = SiMe3. In contrast to the substitution reactions of fluorosilanes with lithiated rings, an unusual oxidation reaction occurs starting from lithiated Me3CN(N=C(CMe3)CH2)Si(CHMe2)2 and ClSiMe2CMe3 to give 29, in which a C-C bond in 4- position links two five-membered rings. The disilane (Me3CSiMe2)2 is formed as a by-product of this reaction. The combination of the N-SiF2CMe3-substituted hydrazones 5 and 14 with t-BuLi in a molar ratio 1 : 2 leads to the colourless, crystalline tricyclic products 30 and 31 which are dimeric 1,2-diaza-3-sila-3,5-cyclopentadienes. The molecular structures of 3, 6, 11, 30, and 31 are reported.
Synthesis and Crystal Structure of a New 1D Oxamidato-bridged Heterobimetallic Polymer
Authors: Lou Wei Jiang , Zhang Yun , Cui Hong , Liu Bao Lin , Tao Ruo Jie
Published: February 2015

A new 1D ladder-like chain coordination polymer, namely, {[Cu(aeoe)Zn(H2O)3 ・ 1.5H2O]2}n (H4aeoe = 2-(2-(2-aminoethylamino)-2-oxoacetamido)terephthalic acid) has been synthesized and characterized by IR, thermogravimetric and single-crystal X-ray diffraction analyses (triclinic, space group P1̄, with a = 9.443(7), b = 9.519(7), c = 11.124(9) Å , α = 65.094(10)°, β = 77.559(10)°, γ = 81.752(10)°, Z = 1).
Treatment of Tetramethylpyrazole and 3,5-Diphenylpyrazole with Dialkylaluminum Hydrides - Hydroalumination versus Deprotonation
Authors: Uhl Werner , Vogelpohl Andreas
Published: February 2015

Treatment of tetramethylpyrazole, N2C3Me4, with equimolar quantities of di(tert-butyl)aluminum hydride leads to the addition of an Al-H bond to one of the C=N double bonds. The dimeric product (1) contains a central six-membered Al2N4 ring in which two tBu2Al+ units are bridging two N2C3 heterocycles. In the zwitterionic, non-centrosymmetric compound one aluminum atom is coordinated by two imino nitrogen atoms, while the second one is bonded to two amide nitrogen atoms. No double hydroalumination occurs upon treatment of tetramethylpyrazole with two equivalents of the hydride. Instead, an adduct (2) of the monomeric hydroalumination product with di(tert-butyl)aluminum hydride was isolated in which the two aluminum atoms are connected by a 3c-2e Al-H-Al bond. A unique trinuclear compound (3) is obtained upon reaction of tetramethylpyrazole with an excess of the sterically less shielded diethylaluminum hydride. It contains two different N2C3 heterocycles: One still contains a C=N double bond similar to that in compounds 1 and 2, while the second one is completely reduced by double hydroalumination to give a saturated heterocycle. The two rings are bridged by three AlEt2 groups. Deprotonation results upon treatment of 3,5-diphenylpyrazole, N2C3H2(C6H5)2, with di(tert-butyl)aluminum hydride.
Synthesis, Crystal Structure, Magnetic, Thermal and Fluorescent Properties of [Co(H2O)4(nia)2](suc)·(H2suc)
Authors: Demir Selcuk , Yilmaz Veysel T. , Mroziński Jerzy , Lis Tadeusz , Hołyńska Małgorzata
Published: February 2015

A new cobalt(II) complex, [Co(H2O)4(nia)2](suc)·(H2suc) [nicotinamide = nia, succinate = suc2−], has been synthesized and characterized by elemental analysis, IR, TG-DTA and single-crystal X-ray diffraction. It contains [Co(H2O)4(nia)2]2+ complex cations, uncoordinated suc2− anios and H2suc species. In the complex cation the cobalt(II) ion is coordinated by four aqua and two nia ligands in a distorted octahedral geometry. The suc2− dianion acts as a counter-ion, while H2suc is present as a molecule of solvation. A three-dimensional network is formed by O-H· · ·O and N-H· · ·O hydrogen bonds. The title complex exhibits luminescence in the solid state at room temperature. The magnetism of the complex was studied over the temperature range 1.8 - 300 K.
Lithium and Aluminum Anthracenyldiimidosulfinates
Authors: Schulz Thomas , Stalke Dietmar
Published: February 2015

9,10-Dibromo-anthracene was lithiated once or twice, and the products were reacted with different sulfurdiimides. The reactions yielded [(THF)2Li(NtBu)2SAnBr] (1), [(Et2O)(LiBr)Li(NtBu)2- SAnBr]2 (2), [Me2Al(NtBu)2SAnBr] (3), [{(THF)2Li(NR)2S}2An] (4: R = tBu; 5: R = SiMe3) and [{Me2Al(NSiMe3)2S}2An] (6). All products were fully characterized by X-ray structure analysis, elemental analysis, NMR and mass spectroscopy. From the solution NMR spectra it is evident that the rotation about the S-C bond is hindered even at r. t. leaving all protons of the anthracene framework non-equivalent.
Polymorphism of Dibromo-tetrakis(tetrahydrofuran-κO)magnesium(II)
Authors: Stern Daniel , Granitzka Markus , Schulz Thomas , Stalke Dietmar
Published: February 2015

The title compound, [MgBr2(C4H8O)4] (1a), forms twinned four-component monoclinic crystals as a new polymorph, space group P21/n with Z´ = 2, in addition to the already known tetragonal polymorph (1b). Although the molecular parameters in the two polymorphs match very well, the packing patterns are significantly different. Furthermore, the correct constitution of the mixed halide bromo-chloro-tetrakis(tetrahydrofuran-κO)magnesium(II) (2) could be determined.
Alkynylsilanes and Alkynyl(vinyl)silanes. Synthesis,Molecular Structures and Multinuclear Magnetic Resonance Study
Authors: Wrackmeyer Bernd , Bayer Stefan , Tok Oleg L. , Klimkina Elena V. , Milius Wolfgang , Kempe Rhett , Khan Ezzat
Published: February 2015

Alkynylsilanes bearing one to four alkynyl groups at silicon, with organyl groups (Me, Ph, Vin), H, Cl at silicon, and with substituents H, nBu, tBu, Ph, C6H4-4-Me, 3-thienyl, CH2NMe2 at the C≡C bond, were prepared, and their 13C and 29Si NMR data are reported. The results of X-ray structure analyses of three representative derivatives [di(phenylethynyl)dimethylsilane, di(phenylethynyl) methyl(phenyl)silane, and tri(phenylethynyl)methylsilane] are presented. The chemistry of mono- and dialkynylsilanes was further developed to prepare compounds with alternating Si atoms and C≡C bonds, affording new dialkynylsilanes as well as numerous new vinylsilanes which have also been characterized by 13C and 29Si NMR spectroscopy in solution. In the case of ethynyl(triphenylsilylethynyl) dimethylsilane, the molecular structure was determined by X-ray diffraction.
Unusual Behaviour During the Route of a Japp-Klingemann Reaction
Authors: Marten Jan , Seichter Wilhelm , Wagler Jörg , Weber Edwin
Published: February 2015

Performing a standard Japp-Klingemann synthesis that involved diazotation of 2,6-dinitroaniline and reaction with pentane-2,4-dione in aqueous hydrochloric acid medium surprisingly yielded a mixture of the expected 2,6-dinitro- and the unexpected 2-chloro-6-nitro-substituted hydrazones. This mixture was isolated as solid-solution crystals containing the components in an approximate ratio of 1 to 2. Based on both, selected compounds of comparison that show the aromatic ring substituents changed in position and intermediate diazonium salts, potential causal connections of the unusual behaviour during the route of the particular Japp-Klingemann reaction were studied. X-Ray crystal structures of the relevant compounds have been determined to support the discussion.
A Cleistanthane Diterpene From a Marine-derived Fusarium Species Under Submerged Fermentation
Authors: Shiono Yoshihito , Ogata Kota , Koseki Takuya , Murayama Tetsuya , Funakoshi Takayuki
Published: February 2015

A cleistanthane-type diterpene, compound 1, was isolated from the marine-derived Fusarium sp. FH-146. The structure of 1 was determined by 1D and 2D NMR spectroscopy. Compound 1 showed moderate antimicrobial, cytotoxic, and phytotoxic activities
Triniobiumoctabromide, Nb3Br8, Revisited
Authors: Habermehl Katja , Meyer Gerd
Published: February 2015

A facile route to single crystals of Nb3Br8 by the reaction of NbBr5 with the wall of the niobium reaction vessel at 800 °C is reported. The crystal structure (a = 707.87(5), c = 3895.7(6) pm, R3̄m, Z = 6) was determined from diffractometer data; the crystal data are compared with those obtained from film data in 1966 which were of already high precision. Triangular {Nb3} clusters with Nb-Nb distances of 288.6(2) pm are surrounded by 13 bromide ligands which bridge them to double layers, {Nb3}(μ3-Br4)i
1/1(μ2- Br1)i
(3/2)・2(μ1-Br2)a-a
6/2(μ1-Br3)a-a-a
3/3 that are stacked to a 12R structure.