bluuebunny/crossref_metadata_2025 huggingface dataset:
Electret Model for the Collective Behaviour of Biological Systems
Authors: Bilz H. , Büttner H. , Fröhlich H.
Published: February 2015

It is suggested that several basic properties of biological systems, such as muscular motions, active transport of energy, etc., may be described in terms of a dynamical model possessing metastable ferroelectric states. The model is based on the observation that confi-gurationally unstable anions, in particular O2-, can lead to ferroelectric phase transitions. Due to the highly variable electronic polarizability of such ions a fourth-order potential is generated which can be the origin of three types of solitary excitations: elastic 'pulse' solitons, ferroelectric 'kink' (or domain-wall) solitons and periodic (coherent) solitary waves. Their possible relation to biological phenomena is discussed.
Stabilization of a Host-Guest Type Complex by Bifurcated Hydrogen Bonds : 18-crown-6 · (2,4-Dinitrophenylhydrazine)2
a
Authors: Hilgenfeld R. , Saenger W.
Published: February 2015

The X-ray structure of the 1:2 host-guest complex between 1,4,7,10,13,16-hexaoxa-cyclooctadecane (18-crown-6) and 2,4-dinitrophenylhydrazine is reported. Crystallo-graphy data are: space group P21/c, a = 8.557(2), b = 16.745(6), c = 12.387(4) Å, β = 117.08(13)°, Z = 2, Dm = 1.37 g · cm-3 , Dc = 1.387 g · cm-3 , m.p. 414 K (decomp.). The present B is 0.11 for 1733 diffractometer data.

In the complex, the two 2,4-dinitrophenylhydrazine molecules are located "above" and "below" the plane of the hexaether and related by an inversion centre. They interact with the macrocyclic host via N-H···0 hydrogen bonds, two of which are bifurcated. All the ether oxygens of the crown serve as hydrogen bond acceptors.
A New Route to 1H-Pyrido[l,2-a]quinazolines
Authors: Soliman Farid S. G. , Stadlbauer Wolfgang
Published: February 2015

The synthesis of 2,5-disubstituted 5,6-dihydro-1 H-pyrido[1,2-a]quinazoline-1,6-diones (3) by reacting monosubstituted bis 2,4,6-trichlorophenyl malonates (1) with 3-aryl-3,4- dihydro-2-methyl-4-quinazolinones (2) is described. Allylation of the pyridoquinazoline 3c with allylbromide afforded the corresponding 3-allyloxy derivative 4. Certain generalizations of the cleavage processes of this series in the MS are reported.
Sulfonamidyls, 4. Ab Initio MO Calculations on Sulfonyl and Carbonyl Substituted Aminyl Radicals
Authors: Teeninga Herman , Nieuwpoort Wim C. , Engberts Jan B. F. N.
Published: February 2015

The relative magnitude of the nitrogen hyperfine splitting constants of sulfonamidyls and carboxamidyls is rationalized in terms of the results of ab initio MO calculations using the "double zeta" basis set of Roos and Siegbahn.
Opening of the B10H10
2- Cage to Give B10H14
Authors: Mongeot H. , Atchekzai H. R.
Published: February 2015

Decaborane B10H14 is formed by opening the B10H10
2- cage in strong acidic medium. The reaction must be carried out in the presence of an inert solvent which dissolves B10H14. The best yields (28%) are obtained when zinc dust is added to the reaction mixture. The conversions of B10H10
2- into B10H14 or B10H12(Et2S)2 probably obey the same mechanism.
Synthese und Eigenschaften von zwei-, drei- und vierkernigen Übergangsmetallkomplexen mit den metallorganischen Chelatliganden [C5H5M{P(OMe)2O}2]⊖ (M = Ni, Pd) [1] / Synthesis and Properties of Bi-, Tri- and Tetranuclear Transition Metal Complexes with the Organometallic Chelate Ligands [C5H5M{P(OMe)2O}2]⊖ (M = Ni, Pd) [1]
Authors: Werner Helmut , Ngo-Khae Tri , Friebel Claus , Köhler Peter , Reinen Dirk
Published: February 2015

Abstract The compounds C5H5M[{P(OMe)2O}2H] and C5H5M[{P(OMe)2O}2]Q (M = Ni, Pd; Q = NH4, Tl) react with metal acetylacetonates M'(acac)n and metal chlorides M'Cln to give the tri-and tetranuclear complexes C5H5M[{P(OMe)2O}2]nM' [n = 2 or 3; M' = Co(II), Cu(II), Zn(II), VO, Al(III), Cr(III), Fe(III)]. The mixed-ligand complexes [C5H5Ni{P(OMe)2O}2]2Ni(NH3)2, [C5H5Ni{P(OMe)2O}2]Ni(acac), [C5H5Pd{P(OMe)2O}2]VO(acac), [C5H5M{P(OMe)2O}2]Pd(2-RC3H4) (M = Ni, Pd; R = Me, But) and [C5H5Ni{P(OMe)2O}2]Rh(C8H12) are obtained following similar synthetic routes. Thermolysis of [C5H5Ni{P(OMe)2O}2]2Ni(NH3)2 in vacuo leads to the trinuclear nickel complex [C5H5Ni{P(OMe)2O}2]2Ni. The magnetic properties as well as the IR, NMR, UV and ESR spectra of the new organometallic chelate complexes are discussed.
Reactions of Amino Acids on 2-Methylmercaptohydantoin Derivatives. Synthesis of Imidazoimidazoline and Imidazoquinazoline Derivatives
Authors: Daboun H. A. , Abd-Elfattah A. M. , Hussein M. M. , Shalaby A. F. A.
Published: February 2015

Treatment of 5-arylidene-2-methylmercaptohydantoins (1a-d) and 5-arylazo-2-methyl- mercaptohydantoins (3a, b) with glycine in acetic acid gave 5-arylidene-N2-carboxy- methylglycocyamidines (2a-d) and 5-arylazo-N2-carboxymethylglycocyamidines (4a, b) respectively. 2 a, b, d were cyclised with acetic anhydride to give imidazoimidazoline derivatives (5a-c). 2-Methylmercapto-3-phenylhydantoin (7) reacted with anthranilic acid to give 9 which previously prepared by the action of aniline on ethyl 2-methylthio-4-oxo- 3,4-dihydro-3-quinazolinylacetate (8). Arylidenes 1 a-c, 10 a-c and arylazo derivatives 3 a, b reacted with anthranilic acid to give imidazoquinazoline derivatives 11a-f and 12 a, b, respectively.
Elektrochemische Eigenschaften von Dihydropyridin-und Pyridinderivaten / Electrochemical Properties of Pyridine and Dihydropyridine Derivatives
Authors: Abou-Elenien G. , Rieser J. , Ismail N. , Wallenfels K.
Published: February 2015

The electrochemical oxidation and reduction properties of different dihydropyridines and pyridines have been investigated in non aqueous solvent as benzonitrile and aceto-nitrile with tetra-n-butylammonium perchlorate as supporting electrolyte at platinium electrodes using DC-voltametry, cycl. voltametry and coulometry. Possible redox-mechanisms are discussed.
Photoproduction of Hydrogen from Water Catalysed by Metal Sulfur Chelates
Authors: Battaglia Rosangela , Henning Rainer , Kisch Horst
Published: February 2015

Metal dithiolenes and other sulfur containing metal complexes catalyse the photoproduction of hydrogen from water in the presence of tetrahydro-or dihydrofurans.
13C, 1H-Spin-Spin Kopplungskonstanten,VIII. 2-Methyl- und 3.5-Dimethyladamantan / 13C, 1H Spin-Spin Coupling Constants, VIII. 2-Methyl- and 3,5-Dimethyladamantane
Authors: Aydin Rafet , Gunther Harald
Published: February 2015

One-bond, geminal and vicinal 13C, 1H coupling constants have been determined for 2-methyl-and 3,5-dimethyladamantane using the derivatives deuterated in position 2 and 1, respectively, and the relation nJ(13C, 1H) = 6,5144 nJ(13C, 2H) for the conversion of the measured nJ(13C, 2H) values. The effect of methyl-substitution on these parameters is discussed.
Die Kristallstruktur von Te6O11Cl2 / The Crystal Structure of Te6O11Cl2
Authors: Abriel Walter
Published: February 2015

Crystals of the title compound are monoclinic (space group P21/m) with a = 6.844(4) Å, 6 = 6.800(4) Å, c= 15.227(9) Å, y= 120.19° and Z = 2. The structure contains infinite cationic [(Te12O22) 4+]∞ -chains with three different sites for tellurium. There are three oxygen atoms in a y-tetrahedral arrangement around Te 1, and four oxygen atoms in a ψ-trigonal-bipyramidal coordination around Te 2 and Te 3.
Isolierbare Chlor [(thio)alkoxy] triorganylphosphoniumchloride als Zwischenprodukte der Oxiran (Thiiran)-Halogenierung mit Dichlorphosphoranen [1] / Isolable Chloro[(thio)alkoxy]triorganylphosphoniumchlorides as Intermediates of the Oxirane (Thiirane)-Halogenation with Dichlorophosphoranes [1]
Authors: Appel Rolf , Gläsel Volker Ingo
Published: February 2015

Isolable chloro[(thio)alkoxy]triorganylphosphoniumchlorides RR2'P-X-CH2R"] + Cl- are synthesized by reaction of oxiranes (2-5) (oxetane (6), thiiranes (18a-c)) with dichloro-phosphoranes (1a-f). Structure and stability are discussed. Thermal Arbusov-rearrange-ment yields vicinal di-resp. trihalo-alkanes and phosphanoxides. The structures are confirmed by 31P{1H} and 13C{1H} NMR data.
Elektrochemische Synthesen, VII [1] Elektrochemische Substitutionsreaktionen an M(CO)6-n (PR3)n-Komplexen (M = Cr, Mo, W) / Electrochemical Syntheses, VII [1] Electrochemical Substitution Reactions of M(CO)6-n(PR3)n Complexes (M = Cr, Mo, W)
Authors: Grobe Joseph , Zimmermann Heinz
Published: February 2015

The principle of electrochemical substitution of metal carbonyls has been applied to monosubstituted derivatives M(CO)5PR3 (M = Cr, Mo, W) with the aim of selective prepa-ration of di-and trisubstituted products M(CO)4(PR3)(PR'3) or M(CO)3(PR3)(PR'3)2. It is shown that, due to simultaneous replacement of CO and PR3 mixtures of products are formed.
Photodimerisierung von 6-trans-Styryl-4-methoxy-2-pyron (= 5.6-Dehydrokawain), 1. Mitteilung / Photodimerisation of 6-trans-Styryl-4-methoxy-2-pyrone (= 5,6-Dehydrokawain)
Authors: Kaloga Macki , Christiansen Ilona
Published: February 2015

The photochemical behaviour of 5,6-Dehydrokawain (1) was investigated. An aceton solution of 1 was placed into a Petri-dish and allowed to evaporate. After a four weeks irradiation with a 100 W light bulb from a distance of 30 cm [1] the main component was isolated. Its structure and configuration is elucidated as r-1,c-2-di[6-(4-methoxy-2- pyronyl) ] - t- 3 ,t -4-diphenyIcyclobutane (2) by means of spectroscopic methods and correlation with β-truxinic acid after degradative reaction.
Zur Kristallstruktur der gemischten Phosphat/Sulfat-Fluorapatite / On the Crystal Structure of Mixed Phosphate/Sulfate Fluoroapatites
Authors: Apella M. C. , Baran E. J.
Published: February 2015

It is shown that the apatite phases of composition Ca10-xNax(PO4)6-x(SO4)xF2 crystallize in a monoclinic unit cell, which is related to those of pure fluoroapatite by doubling the b-parameter. Some comparisons with related systems are made and a possible explanation for the origin of the small monoclinic distortion is advanced
On the Hydration of N-Isomeric 5-Tetrazolecarbaldehydes
Authors: Moderhack Dietrich
Published: February 2015

Of the title aldehydes 1 and 2, the isomers 1 are more strongly hydrated when kept in dioxan + water or hexadeuterioacetone + deuterium oxide mixtures, respectively. The uncatalysed reaction R-CHO + H2O →R-CH(OH)2 proceeds much faster with compounds 1
Perfluormethyl-Element-Liganden, XXV [1] Organozinnverbindungen als Reagenzien, IV: Spaltungsreaktionen der Element-Element-Bindung in Komplexen des Typs M(CO)5ER2ER′2 bzw. M(CO)5ER2E′R′ mit Trimethylstannan (R, R′ = CH3, CF3; E = P, As; E′ = S, Se, Te; M = Cr, Mo) / Perfluoromethyl-Element Ligands, X X V [1] Organotin Compounds as Reagents, IV:Cleavage Reactions of the Element-Element Bond in Complexes of the Type M(CO)5ER2ER′2 and M(CO)5ER2E′R′ , Respectively, with Trimethylstannane (R, R′ = CH3, CF3; E = P, As; E′ = S, Se, Te; M = Cr, Mo)
Authors: Grobe Joseph , Le Van Due
Published: February 2015

The cleavage of element-element bonds in ligands of the type R2EER′2 and R2EE′R′ (R, R′ = CH3, CF3; E = P, As; E′ = S, Se, Te) coordinated to M(CO)5-fragments (M = Cr, Mo) by Me3SnH (Me = CH3) has been studied in some detail by NMR spectroscopic measurements (1H, 19F). In comparison with the analogous reactions of the free ligands, the rate of reaction is considerably reduced, wheras the cleavage direction is generally retained. Possible reaction intermediates have been synthesized by independent routes and tested under comparable conditions.
Oligophosphin-Liganden, III [1] Bis(3-diphenylphosphinopropyl)phenylphospbinchloroiridium(I) * * und dessen Carbonyl-und Hydridderivate / Oligophosphine Ligands, III [1] Bis(3-diphenylphosphinopropyl)phenylphosphinechloroiridium(I) and its Carbonyl and Hydride Derivatives
Authors: Arpac Ertugrul , Dahlenburg Lutz
Published: February 2015

The title complex, IrCl(bdpp) (1), where bdpp = PhP[(CH2)3PPh2]2, has been obtained from [IrCl(C8H14)2]2 and the triphosphine ligand. Characteristic 31P NMR data of 1 dissolved in THF are δ(P̲Ph2) = 2.7 and δ(P̲Ph) = - 19.9 with cis-2J(P̲IrP̲) = 32.8 Hz. Reaction of 1 with CO proceeds stepwise to yield five-coordinate IrCl(CO)(bdpp) (2) and ionic [Ir(CO)2(bdpp)]Cl (3). A trigonal bipyramidal geometry with equatorial CO ligands is assigned to the cation of 3 on the basis of its v(CO) infrared intensities. When allowed to react with HCl, 1 gives the monohydride IrHCl2(bdpp) (4). Similarly, the dihydride IrH2Cl(bdpp) (5) is formed from 1 and H2. As has been established by IR and NMR spectroscopy, 4 and 5 adopt cis-mer-octahedral structures.
Solvent Effects on the IR Spectra of N-Methylacetamide
Authors: Manzur J. , González G.
Published: February 2015

The solvent effect on the v(N-H) amide I and amide II IR bands of N-methylacetamide were investigated. The frequency shifts could be related to the solvent donor and acceptor num-bers by mean of a two parameters relationship that accounts for the mutual influence between the two interacting sites of the amide.
Übergangsmetall-Carben-Komplexe, CXIX. Carbonyl [ethoxy(triphenylsilyl)carben] (dinitrosyl)eisen/ Transition Metal Carbene Complexes, CXIX. Carbonyl[ethoxy(triphenylsilyl)carbene](dinitrosyl)iron
Authors: Fischer Ernst Otto , Stadler Peter
Published: February 2015

Dicarbonyl(dinitrosyl)iron reacts with triphenylsilyllithium and subsequently with triethyloxonium tetrafluoroborate to give carbonyl[ethoxy(triphenylsilyl)carbene](dinitrosyl) iron.
Complexes of 1,2,4-Triazoles, Part XVII The Crystal Structure of Tris-μ-(4-ethyl-1,2,4-triazole-N1,N2)- (4-ethyl-1,2,4-triazole-N1)-aquo-bis [bis(thiocyanato-N)- nickel(II)]hydrate, Ni2(C4N3H7)4(H2O)(NCS)4 ·H2O(x ≃ 2.5)
Authors: Vos Ger , Kok Anthonie J. de , Verschoor Gerrit C.
Published: February 2015

The crystal structure of Ni2(C4N3H7)4(H2O)(NCS)4 · 2.5 H2O has been determined by X-ray diffraction techniques. The compound crystallizes in the monoclinic space group P21/n with a = 15.121(4), b= 13.237(2), c= 18.069(3), β = 94.71(2)° and Z = 4; R = 0.040 (Rm = 0.051). The compound consists of dimeric units in which two Ni ions are bridged by three ethyltriazole (Ettrz) groups. For one Ni, two N donating NCS- groups and an Ettrz coordinating by only one N atom complete the NiNe octahedron. The other Ni atom, which is also octahedrally coordinated, has a coordinated water molecule instead of a monodentate Ettrz.
NMR-Untersuchungen an Organoelement(IVb)-phosphinen, VII [1] 119Sn-NMR-Untersuchungen an Trimethylstannylphosphin-substituierten Verbindungen der Pseudonickelcarbonylserie/NMR Studies on Organoelement(IVb)-phosphines, VII [1] 119Sn NMR Spectroscopic Investigations on Trimethylstannylphosphine Substituted Compounds of the Pseudonickelcarbonyl Series
Authors: Meißner Manfred , Kroth Heinz-Jürgen , Köhricht Karl-Heinz , Schumann Herbert
Published: February 2015

119Sn NMR chemical shifts as well as 1H119Sn and 31P 119Sn NMR coupling constants are reported and discussed for compounds of the type [(CH3)3Sn]n[tC4H9]3-n P (n = 1, 2, 3) and related complexes Mn(NO)3L, Fe(CO)(NO)2L, Co(CO)2(NO)L and Ni(CO)3 L (L = organotin phosphine).
Eine neue Form von Al(H2PO4)3 mit dreidimensionaler Al-O-P-Vernetzung/ A New Form of Al(H2PO4)3 with Three-Dimensional Al-O-P Crosslinking
Authors: Brodalla Dieter , Kniep Rüdiger , Mootz Dietrich
Published: February 2015

3
∞[Al(H2PO4)3] has been prepared and characterized as a second modification of aluminium tris(dihydrogenphosphate). Its crystal structure is a three-dimensional Al-O-P network of AlO6 octahedra, linked by common vertices through O2P(OH)2 tetrahedra with six further octahedra. Each P-OH group is a proton donor as well as a proton acceptor of O-H···O hydrogen bonds arranged in angular chains of alternating polarity in macroscopic domains.
Zur Stereochemie der Bisaboloide aus Matricaria chamomilla L/On the Stereochemistry of the Bisaboloids from Matricaria chamomilla L.
Authors: Flaskamp Elmar , Nonnenmacher Gerhard , Zimmermann Gottfried , Isaac Otto
Published: February 2015

The stereochemistry of the bisaboloids in chamomile-with the exception of bisabolol-oxide C-has been elucidated. The in-vitro-examination of the mutual convertibilities of some bisaboloids gave evidence for the stereochemical accordance of the common chiral centres of all the bisaboloids. The absolute configurations of the remaining third asymmetric carbon atoms in bisabololoxide A and B have been determined by NMR spectrometric studies in comparison with their unnatural semisynthetic epimers. All the stereogenic centres of the bisabololoxides A and B, of (-)-α-bisabolol and of bisabolonoxide A turn out to be S-configurated.
Synthese und Molekülstruktur der dreikernigen Cluster-Verbindung (η5C5Me5)IrFe2(CO)9 / Synthesis and Molecular Structure of the Trinuclear Cluster Compound (η5-C5Me5)IrFe2(CO)9
Authors: Guggolz Ernst , Ziegler Manfred L. , Kalcher Willibald , Plank Johann , Riedel Doris , Herrmann Wolfgang A.
Published: February 2015

Reaction of triirondodecacarbonyl (1) with the dinuclear chloroiridium complex [(η5 -C5Me5)Ir(μ-Cl)Cl]2 (2) in benzene at 50 °C yields the novel mixed iron iridium cluster of composition (η5 -C5Me5)IrFe2(CO)9 (8) the molecular structure of which has been established by X-ray diffraction methods. The mononuclear half-sandwich complex (η5 -C5Me5)Ir(CO)2 (4) present in the reaction mixture was found to represent the immediate precursor of the cluster compound 8.
Photochemische Reaktionen von Re2(CO)10 in Gegenwart von Cyclooctatetraen und 1.3-Butadien / Photochemical Reactions of Re2(CO)10 in the Presence of Cyclooctatriene and 1,3-Butadiene
Authors: Guggolz Ernst , Oberdorfer Franz , Ziegler Manfred L.
Published: February 2015

Rhenium Carbonyl Olefin Complexes Re2(CO)io has been photolyzed in the presence of cyclooctatetraene, 1,3-butadiene and 1,4-pentadiene, respectively. In pentane solutions the species (CO)4Re-μ-(η3 :η1-C4H6)Re(CO)5, (CO)4Re-μ-(η2:η2-C4H6]Re(CO)4 (11) and HRe3(CO)14 could be isolated with 1,3-butadiene. C8H8 yielded several compounds of which the following could be unequivocally characterized (CO)4Re-μ-(η3:η1-C8H8)Re(CO)5 (14), (η2-C8H8)Re(CO)4-μ-(1,2,8-η3:5-η1-C8H8)-Re(CO)4 and (CO)3Re-μ-(η4:η4-C8H8)Re(CO)3.11 and 14 have been characterized by X-ray structure analysis.
Anhydride und Thioanhydride von tert-Butylstibinig-und -stibonigsäuren / Anhydrides and Thioanhydrides of tert-Butylstibinous-and Stibonous Acids
Authors: Breunig Hans Joachim , Kischkel Helmut
Published: February 2015

The reactions of di-tert-butylantimony chloride with sodium hydroxide or sodium sulfide yield new anhydrides or thioanhydrides of tert-butylstibinous acids, which have structures with bridging oxygen or sulfur atoms. Analogous reactions of tert-butylantimonydichloride produce the first examples of anhydrides or thioanhydrides of tertbutylstibonous acids, which have cyclic structures (t-BuSbE)n E = O, n = 3, 4; E = S, n = 2, 3, 4, 5. Structural evidence is based on IR, 1H NMR and MS data.
Koordinationschemie reduzierter N-Heterozyklen. Komplexe des Pyrazin-Radikalanions mit Phenylmetallkationen +MPh von Beryllium, Magnesium und Zink / Coordination Chemistry of Reduced N-Heterocycles. Complexes of Pyrazine Anion Radical with Phenyl Metal Cations +MPh of Beryllium, Magnesium and Zinc
Authors: Kaim Wolfgang
Published: February 2015

The diphenyls MPh2 (M = Be, Mg, Zn, Cd, Hg) have been reacted with pyrazine (Pz) in tetrahydrofuran. Only the magnesium derivative undergoes electron transfer to yield the 1:1 radical complex [Pz(MgPh)]·. However, in the presence of sodium or potassium persistent 1:2 complexes [Pz(MPh)2]+. are formed with M = Be, Mg, Zn. Use of the higher homologues CdPh2 and HgPh2 leads to reduction to the metals. The 1:2 complexes have been characterized by ESR spectroscopy; metal coupling constants of 9Be, 25Mg and 67Zn could be determined in natural isotopic abundance.
Condensation of 3-Aryl-2,4-dicarboethoxy-5-hydroxy-5-methylcyclohexanones with o-Phenylenediamine, Thiourea, α,β-Unsaturated Ketones and Hydrazines
Authors: Metwally Mohamed Abbas , Afsah El-Sayed , Amer Fathy A.
Published: February 2015

Reaction of the title compound 1 with o-phenylenediamine afforded either the diaze-pinones (2) or the amides (3). Treatment of 1 with thiourea gave the thiouracils (4). The indazoles (5) gave diacetyl or diphenylsulphonyl derivatives (6, 7) on treatment with acetic anhydride or benzenesulphonyl chloride, respectively. Condensation of 1 with benzenesulphonhydrazide gave the 2-substituted indazole (8). Michael condensation of 1 with anisalcyclohexanone gave 9.
Polymergebundenes Sulfonylazid zur entformylierenden Diazogruppen-Übertragung und zur Diazo -cyclopolyen -Synthese / Polymer Anchored Sulfonylazide for Deformylating Diazo Group Transfer and the Synthesis of Diazo-cyclopolyenes
Authors: Dürr Heinz , Hauck Gerhard , Brück Wolfgang , Kober Helge
Published: February 2015

Polymer anchored sulfonylazide is compared with its efficiency in the diazogroup transfer reaction of tosylazide. The resulting yields with the polymeric reaction are slightly lower than with tosylazide.

However the greater thermostability of polymeric sulfonyl azide and its workup procedure make this alternative very attractive for synthesis. The reaction of polymeric sulfonyl azide with cyclic polyenes gives very small yields compared with the monomeric reaction. The attempt to generate diazocyclononatetraene by an alternative route leads only to the secondary product namely indene. At low temperature, and intermediate diazo-compound is, however, observed, which is tentatively assigned to structure 12.
3.5-Dihydroxy-6.7.8-trimethoxyflavon aus Heiichrysum graveolens: Bestätigung der Konstitution / Confirmation of the Structure of an Extractive from Helichrysum graveolens as 3,5-Dihydroxy-6,7,8-trimethoxyflavone
Authors: Hansel Rudolf , Khaliefi Faeis , Pelter Andrew
Published: February 2015

By X ray and NMR techniques the flavone structure for an extractive from Helichrysum graveolens has been confirmed. An extractive from an Artemisia sp. previously assigned the same structure must therefore have a different constitution.
Ein Triarsanato(1.3)-Chelat des Titans / A Triarsanato(1,3) Chelate of Titanium
Authors: Köpf Hartmut , Gorges Ulrich
Published: February 2015

When the cyclopentaarsane (AsC2H5)6 is reacted in a 1:2 or 1:5 molar ratio with metallic potassium in THF, soluble dipotassium catenaarsanes of the assumed stoichiometry K2(ASC2H5)5 (1) or K2(ASC2H5)2 (2), respectively, are formed. On reaction with (C5H5)2TiCl2 in THF, both the red 1 or the greenish 2 lead to the same dark-brown, airsensitive triarsanato complex (C5H5)2Ti(AsC2H5)3 (3).
Metallorganische Verbindungen der Lanthanoiden, XII [1] Dicyclopentadienyl(diorganophosphin) -Derivate von Terbium, Holmium, Erbium, Thulium, Ytterbium und Lutetium / Organometallic Compounds of the Lanthanides, XII [1] Dicyclopentadienyl(diorganophosphine) Derivatives of Terbium, Holmium, Erbium, Thulium, Ytterbium, and Lutetium
Authors: Schumann Herbert , Frisch Georg-Michael
Published: February 2015

Organolanthanide Compounds, Organophosphines Lithium (di-terJ-butyl)phosphide and lithium(£erf-butyl)phenyl phosphide react with the dicyclopentadienyllanthanide chlorides of terbium, holmium, erbium, thulium, ytterbium, and lutetium with elimination of lithium chloride and formation of the corresponding dicyclopentadienyl(organopho8phine) lanthanide derivatives. NMR data of the lutetium compounds are given.
Zur Hochdruckpolymorphie von Bal2 / High Pressure Polymorphism of Bal2
Authors: Beck H. P.
Published: February 2015

High pressure investigations of Bal2 yielded a new polymorph, which could be quenched and characterized by X-ray methods. PbCl2-type Bal2 is converted to an anti-Fe2P-type structure with more regular coordination polyhedra and an increase in effective coordination numbers. We discuss changes in bonding type by comparing the Madelung part of lattice energy in the two polymorphs.
Darstellung und Charakterisierung von Selenophosgen / Preparation and Characterization of Selenophosgene
Authors: Darmadi Alexius , Haas Alois , Willner Helge
Published: February 2015

Selenophosgene was prepared for the first time by vacuum pyrolyses of 2,2,4,4-tetra-chloro-1,3-diselenetane. The dark blue compound, stable only below -130 °C, was characterized by mass, low temperature UV, IR matrix and Raman matrix spectroscopy.
Struktur und Entstehung des farbigen Simon-Awe-Komplexes / Structure and Formation of the Coloured Simon-Awe Complex
Authors: Wiegrebe Wolfgang , Vilbig Margit
Published: February 2015

A nice blue colour arises from acetaldehyde, Na2[Fe(CN)5NO] • 2 H2O and piperidine (Simon-Awe Reaction). Structure elucidation of the blue material (leading to 1) by combustion analysis, ligand exchange to [Fe(CN)6]4-, reduction to β-aminoethanol and hydrolysis to glyoxal are described. - The blue complex does not contain the amine moiety but is formed via an enamine, an colourless immoniumsalt 2 and its hydrolysis to 1. - Loach's experiments are re-evaluated
Lanthaniden-Verschiebungen in der 1H- und 13C-Kernresonanzspektroskopie zur Konstitutionsermittlung von Thiadiazoloxiden / Lanthanide Induced Shifts in the 1H and 13C Nuclear Magnetic Resonance Spectroscopy for Structure Elucidations of Thiadiazole Oxides
Authors: Plücken Udo , Meier Herbert
Published: February 2015

A systematic investigation of the LIS-method for structure elucidations is performed on the basis of thermally generated monoxides of 1,2,3-thiadiazoles. A calculation process for the evaluation of lanthanide induced shifts according to the McConnell-Robertson equa-tion was developed. The program can be applied to underdetermined systems with fewer variables than chemically not equivalent X H plus 13 C nuclei. A quality criterium for the method is given by 4-phenyl-l,2,3-thiadiazole-3-oxid -wellknown by an X-ray analysis.
Intradiol Aromatic Ring Cleavage in a Dioxygenase Model System
Authors: Brown Dennis G. , Hughes William J.
Published: February 2015

Dioxygenase Model, Copper, Catechol The complex (3-n-nonylcatecholato)(1,10-phenanthroline)copper(II) reacts with molecular oxygen to give an isomeric mixture of 2-n-nonylmuconic acid and several secondary oxidation products. The catecholato ligand is oxidatively cleaved in an intradiol fashion reminescent of the reactions catalyzed by intradiol aromatic dioxygenases. The 1,10-phenanthroline ligand can be quantitatively recovered and is not oxidized. In addition to characterization of oxidation products, the kinetics of oxygen consumption have been analyzed. The rate law for oxygen uptake is -d[O2]/dt = k[O2] [copper]2 .
Solid-Phase Synthesis of Peptides via a,β-Unsaturated Amino Acids. Incorporation of the Amide Gronp in encZo-Positions
Authors: Nöda Kosaku , Gross Erhard
Published: February 2015

Dehydroalanine is introduced as pseudoprotecting group for the to-amide function of Asn and Gin in solid-phase peptide synthesis. Using Boc-X(Dha-NHMe)-OH (X = Asp or Glu), the model peptides,

L-Leu-L-Asn-Gly-NH2 and

L-Leu-Lr-Gln-Gly-NH2, were synthesized
Darstellung von triorganyl-und dialkylaminosubstituierten Fluorphosphoniumsalzen / Preparation of Triorgano-and Dialkylamino-substituted Fluorophosphonium Salts
Authors: Bartsch Rainer , Stelzer Othmar , Schmutzler Reinhard
Published: February 2015

Fluorophosphonium bromides are easily accessible by ligand exchange reactions between bromophosphonium bromides and difluorophosphoranes. The reaction between fluorophosphoranes of different Lewis acidity is investigated. Fluorophosphonium-organo-fluorophosphates are formed in some cases by transfer of fluoride ion. Alkylamino-substituted fluorophosphonium bromides may be obtained by Br/F-exchange in bromo-phosphonium bromides with sodium fluoride. The products are characterized by means of 1 H, 19 F, and 31 P NMR spectroscopy.
Umlagerungsreaktionen von lithiierten Silylhydroxylaminen mit Fluorsilanen / Rearrangement Reactions of Lithiated Silylhydroxylamines with Fluorosilanes
Authors: Bentmann Dieter , Klingebiel Uwe
Published: February 2015

Halogenosilanes, with the exception of CH3SiF3 and SiF4, react with lithiated bis-(trimethylsilyl)hydroxylamine in ether to yield substituted hydroxylamines, and LiF. In the analogous reaction with trifluoromethylsilane and tetrafluorosilane the products undergo an intramolecular rearrangement to form silylaminosiloxanes.
(MeSn)4Se6, Geometrie und Schwingungsformen eines Adamantan-Gerüstes aus Zinn-Selen-Bindungen / (MeSn)4Se6, Geometry and Vibrational Modes of an Adamantane Framework Formed by Tin-Selenium Bonds
Authors: Blecher Axel , Dräger Martin , Mathiasch Bernd
Published: February 2015

The title compound has been synthesized by reaction of MeSnBr3 and NaHSe in aqueous solution. The X-ray structure determination showed adamantane-like molecules (Sn-Se 253(1), Sn-C 215(1) pm) arranged in a quasi hexagonal-close packing. The atomic coordinates were used for an analysis of the vibrational spectra, yielding information on the distribution of the potential energy for the normal modes in terms of internal co-ordinates and a set of force constants. The valence force constants f(Sn-Se) 154(6), f(Sn-C) 216(2) N/m) are compared with those in related monocyclic molecules.
Trigonal Prismatic or Octahedral Surrounding in Sheet Oxides ?
Authors: Delmas Claude , Braconnier Jean-Jacques , Fouassier Claude , Hagenmuller Paul
Published: February 2015

Layer Oxides, Intercalate, Trigonal Prismatic of Octahedral Surrounding According to the oxygen packing two types of alkali ion surroundings (octahedral or trigonal prismatic) are possible in the AxMO2 sheet oxides or the related A2MO3 compounds. The stability of both environments is discussed from the geometrical and electrostatic view points. Structural transitions to metastable forms can be induced by high pressure, intercalation, desintercalation or exchange reactions. The possibility of room temperature transformations can be anticipated from the relationships between the various oxygen packings.
Thio-hydroxoanionen des Germaniums: Darstellung, Struktur und Eigenschaften von Na2GeS2(OH)2 · 5 H2O / Thio-hydroxo Anions of Germanium: Preparation, Structure and Properties of Na2GeS2(OH)2 · 5 H2O
Authors: Krebs Bernt , Wallstab Hans-Joachim
Published: February 2015

Pure thio-hydroxo-germanates can be prepared from aqueous solutions by reactions of stoichiometric amounts of either sodium sulfide and GeO2, or NaOH and GeS2. The preparation of colourless crystalline Na2GeS2(OH)2 · 5 H2O is reported. The compound is characterized by a single-crystal X-ray structure analysis. It is orthorhombic, space group Pbcn, with a = 10.752(2), b= 13.787(2), c = 14.150(2) Å. The structure contains novel monomeric GeS2(OH)2
2- anions with Ge-S bond distances of 2.150(1) and 2.145(1) Å and with Ge-O lengths of 1.809(3) and 1.815(3) Å. An extensive S ··· HO-and O -HO-hydrogen bond system connects the anions with the octahedrally coordinated Na+ ions. The vibrational spectra are reported. The symmetric GeS2 andGeO2 stretching vibrations in the anion are observed at 415 and 618 cm-1.
Ternary Intercalation Compound of Graphite with Aluminum Fluoride and Fluorine
Authors: Nakajima Tsuyoshi , Kawaguchi Masayuki , Watanabe Nobuatsu
Published: February 2015

A ternary intercalation compound of graphite with AlF3 and F2, CxF(AlF3)y was prepared under fluorine atmosphere at temperatures of 20-400 °C. The typical 1st stage compound has a composition of C6F(AlF3)0,15 with a repeat distance of 940 pm. Rapid progress in the reaction led of the formation of graphite fluoride, (C2F)n. ESCA spectra indicate that the chemical bond between host graphite and intercalated fluorine has nearly covalent nature similar to that for (C2F)n.
Ligandenstabilisierung durch Komplexbildung: P.P′.P″ -Triaminocyclotriphosphazan und adamantananaloges Tetraphosphorhexaimid / Stabilisation of Ligands by Complex Formation: P,P′,P″ -Triaminocyclotriphosphazane and an Adamantane-Analogous Tetraphosphorus Hexaimide
Authors: Nöth Heinrich , Thorn Volker
Published: February 2015

The thermal decomposition of (CO)5MP(NH2)3 (M = Cr, Mo, W) has been studied. No definite products were obtained for M = W but the molybdenum complex yielded [(CO)5MoP]4(NH)6. The same type of complex results with M = Cr, in addition to [(CO)5CrP(NH)NH2]3. The pentacarbonylchromium groups may be removed from the adamantane type [(CO)5CrP]4(NH)6 with sulfur. The new compound S4P4(NH)6 results in this reaction. This compound is also a by-product in the thermal decomposition of SP(NH2)3. Attempts to prepare P4(NH)6 by desulfurisation from S4P4(NH)6 or from the chromium complex failed.
Cyclodiaza - λ6-thiane / Cyclodiaza-λ6-thianes
Authors: Tesky Frank-Michael , Mews Rüdiger , Krebs Bernt
Published: February 2015

From sulfurtriimides and N-perfluoroalkyl-isocyanates or -sulfinyl-amines SSS′S′-tetra-imino-(11 a-c), SS′-dioxo-SS′-di-imino-(19 and 28), and SSS′-tri-oxo-S′-imino-cyclodiaza-λ6 -thianes (34) were prepared. The structures of 11 b, 19 and 28 are discussed, general rules for the stability of these ring systems are derived.
Organometalloidal Compounds with o-Phenylene Substituents, VII [1] Crystal and Molecular Structure of 10,15-Dihydro-5H-5,10,15-trioxa-tribenzo [a,d,g] cyclononene (Trimeric o-Phenylene Oxide) and its Implications Concerning Preferred Conformations of Compounds (Arylene)3X3
Authors: Deuten Klaus von , Klar Günter
Published: February 2015

The title compound crystallizes with an orthorhombic P cell, a = 893.5(1), b = 949.2(2), c = 1520.6(3) pm; Z = 4, space group Pnab. Its molecular conformation has crystallographic C2-symmetry with one phenylene ring in the plane of the three oxygen atoms, the other rings extending almost perpendicularly above and below this plane. The two kinds of oxygen atoms in the molecule show characteristic differences with respect to CO bond lengths and COC bond angles; only the oxygen lying on the C2-axis (joining the "perpendicular" rings) exhibits π-interactions with its phenylene rings. The influence of electronic and steric factors on the preferred conformation of the class of compounds (arylene)3X3 is pointed out.
Chemie polyfunktioneller Liganden, 69 [1] Über drei Organo-Arsen-Käfigverbindungen mit Noradamantanstruktur / Chemistry of Polyfunctional Ligands, 69 [1] Three Organo-Arsenic Cage Compounds with Noradamantane Structure
Authors: Ellermann Jochen , Lietz Martin
Published: February 2015

The reaction of l.l.l-tris(diiodarsinomethyl)ethane, CH3C(CH2Asl2)3 (1), with H2C(COOC2H5)2, H2C(COOCH3)2 and H2C(COC6H5)2 in presence of the auxiliary base (C2H5)3N gives the noradamantane structured compounds CH3C(CH2As)3E2 [E=C(COOC2H 5)2 (2), C(COOCH3)2 (3) and C(COC6H5)2 (4)].

The new compounds have been characterized by mass spectrometry and infrared, Raman and 1H NMR spectroscopy.
Sn21Cl16(OH)14O6, das sogenannte basische Zinn(II)-chlorid [1] / Sn21Cl16(OH)14O6, the So-called Basic Tin(II) Chloride
Authors: Schnering Hans Georg von , Nesper Reinhard , Pelshenke Hermann
Published: February 2015

Sn21Cl16(OH)14O6 has been shown to be the correct composition of the so-called basic tin(II) chloride. Well crystallized colourless platelets of pearly luster were precipitated from homogeneous solution. The structure (single crystal X-ray diffraction data, corrected for absorption and twinning, R32-D3
7, a = 1001.8 pm, c = 4403.0 pm, Z = 3, R = 0.045) is characterized by two different nets M1 = 2
∞ [Sn5(OH)6Cl6]2- and M2= 2
∞[Sn8O3(OH)4Cl3]3+ stacked along [001] with intercalated Cl- ions. M1 and M2 consist of condensed [Sn(OH)3] and [Sn(OH)2Cl2] or [Sn(OH)3] and [Sn(OH)2Cl]-type groups, respectively. M2 contains additionally the new cubane group [Sn4O3(OH)] which is linked by [Sn(OH)3]- and [SnCl]-fragments. The negative charge distribution seems to dominate the arrangement of chlorine atoms, oxygen atoms and lone pairs leading to well constructed hexagonal nets. All but one of the Sn atoms exhibit the typical ψ-trigonal pyramidal coordination. The ψ-trigonal bipyramidal [Sn(OH)2Cl2]-coordination of Sn(4) can be interpreted as a reaction-transition state.
In the Search for New Anticancer Drugs, II1 Antitumor Activity, Toxicity and Electron Spin Resonance of Spin Labeled Thio-TEPA Derivatives
Authors: Gutierrez Peter L. , Konieczny Maria , Sosnovsky George
Published: February 2015

The spin labeled analog of Thio-Tepa, 1-oxyl-2,2,6,6-tetramethyl-4-piperidyl-N,N;N′,N′−bis (ethylene)−phosphorodiamidothioate (SL−O−TT), which contains a nitroxyl free radical linked by an oxygen bridge to phosphorus, has antitumor properties against P388 murine leukemia (T/C = 242) and a higher therapeutic ratio (5.15) than its parent compound, Thio-TEPA (2.75). The drug is less toxic to P388 cells in culture as judged by the 3H-thymidine uptake. On the basis of electron spin resonance spectroscopy using L1210 cells incubated with SL−O−TT, it is concluded that the drug is bound to cells in culture in such a way as to restrict the motion of the nitroxyl label. A second spin labeled analog, 1-oxyl-2,2,6,6-tetramethyl-4-amino-piperidyl-N,N;N′,N′−bis (ethylene)−phosphorodiamidothioate (SL−NH−TT), containing a nitroxyl label linked by a nitrogen bridge to phosphorus, first synthesized by Russian workers, was prepared by an improved procedure in 95% yield. In vivo results indicate that this analog has about the same therapeutic value (2.73) as Thio-TEPA (2.75), and that higher doses of this compound are required than those for both the O-bridged analog and Thio-TEPA to achieve maximum T/C values.
Das Allopolarisierungsprinzip und seine Anwendungen, VI [1] Die Alkylierung von Enolatanionen: Polarität und Regioselektivität / The Allopolarization Principle and its Applications, VI [1] The Alkylation of Enolate Anions: Polarity and Regioselectivity
Authors: Gompper Rudolf , Vogt Hans-Hubert , Wagner Hans-Ulrich
Published: February 2015

The O/C methylation ratio in the reaction of sodium enolates with dimethylsulfate depends on the polar(electronic) effect of substituents. The relative π-charge density Px/y = 1x/1y can be used as a measure for the polarity of ambifunctional anions; in case of enolate anions Po/c = 1o/1c-The change of the regioselectivity Sf = log Qo/Qc in the alkylation of enolates is a function of the change in the polarity Po/c; ⊿Sf = f (⊿Px/y). The polar effect of substituents influences the charge control during the alkylation process via a change of the polarity of the enolate system: The higher the polarity of the anion, the stronger the charge control and the higher the yield of enol ether (O-alkylation).
2,3-Dihydro-1,3-diborole: Synthesen, Reaktionen und Eigenschaften [1] / 2,3-Dihydro-1,3-diboroles: Syntheses, Reactions and Properties [1]
Authors: Siebert Walter , Ender Ulrich , Herter Wilfried
Published: February 2015

Redox reactions between CH2(BI2)2 and hexyne-3 or butyne-2 lead to 4,5-dialkyl-1,3-diiodo- 2,3-dihydro-1,3-diboroles. In 2c and 2d the B - I function is substituted by CI, OC2H5, SCH3, N(CH3)2, CH3, C2H5 and C6H5 to yield the corresponding derivatives 2e-21. 1H, 11B, and 13C data of 2 are reported.
Methoden zur Darstellung kationischer Rhenium-pentacarbonyl(thiazylhalogenid)-Komplexe / Methods for the Preparation of Cationic Rhenium-pentacarbonyl(thiazylhalide) Complexes
Authors: Hartmann Gabriele , Mews Rüdiger
Published: February 2015

The preparation of [Re(CO)5NSX]+AsF6
- (2a X = Cl, 2b X = Br) is possible (a) by metathesis from [Re(CO)5NSF]+AsF6
- with SiX4, (b) by insertion of the NS+-cation into the metal-halogenbond of Re(CO)5X and (c) by nucleophilic halide addition to the sulfur in the dicationic thionitrosyl complex [Re(CO)5NS]+
+.
Übergangsmetallkomplexe mit Schwefelliganden, XI* Molybdän-Oxo-Komplexe des Typs [Mo(IV)(O)(S2)2], [Mo(VI)(O)2(S4)], [MO(IV)(O)(S4)] und [Mo(IV)(O)(S5)] mit zwei-, vier- und fünfzähnigen Thioether-thiolat-Liganden (Sx = mehrzähniger Thioether-thiolat-Ligand) / Transition Metal Complexes with Sulfur Ligands, XI* Molybdenum Oxo Complexes of the Type [Mo(IV)(O)(S2)2], [Mo(VI)(O)2(S4)], [MO(IV)(O)(S4)] and [Mo(IV)(O) (S5)] with Bi-, Tetra- and Pentadentate Thioether-Thiolate Ligands (SX = Multidentate Thioether-Thiolate Ligand
Authors: Sellmann Dieter , Zapf Lothar
Published: February 2015

MoCl

Reacting [Mo(O)2(acac)2] (acac- = acetylacetonate) with the tetradentate thioether-thiol ligand 2,3,8.9-dibenzo-1,4,7,10-tetrathiadecane (dttd-H2) yields cis-[Mo(O)2(dttd)] ; this compound is reduced by PPh3 to give [MoO(dttd)], which is also obtained from [MoCl2(dttd)] and H2O. Depending upon the concentrations of the reactants [4(THF)2], CH
3SC6H4SH and H2O , in THF the products [MoO(CH
3SC6H4S)2] or [MoCl2(CH3SC6H4S)2] are formed. In the analogous reaction between [MoCl4(THF)2] and the pentadentate ligand 2,3,11,12-dibenzo- 1,4,7,10,13-pentathiatridecane (dpttd-H2) in THF/H2O. [MoO(dpttd)] is obtained exclusively. Due to their poor solubility, the Mo(IV)-oxo complexes show only limited reactivity only; with NO reductive nitrosylation to cis-Mo(NO)2 complexes is observed.
Preparation and Characterization of Some Isoelectronic Boron-Nitrogen Analogs of Substituted Uracil [1]
Authors: Bielawski Jacek , Niedenzu Kurt , Stewart Jean S.
Published: February 2015

Several 1,3,5-triaza-2-boracyclohexa-4,6-diones, which are isoelectronic analogs of substituted uracil, have been prepared by condensation reactions of boranes with biurets. They include species containing a NH or BH unit as potentially reactive sites. The latter are extremely sensitive to hydrolysis but are readily handled as the 2-methylaminoethanol derivative containing fourcoordinate boron.
3-Substituierte 1-AIkoxyindolin-2-one aus N-Alkoxy-2-phenylgIycoIamiden und Dicyclohexylcarbodiimid / 3-Substituted 1-Alkoxyindolin-2-ones from N-Alkoxy-2-phenylglycolamides and Dicyclohexylcarbodiimide
Authors: Geffken Detlef , Strohauer Knuth
Published: February 2015

The reaction of N-alkoxy-2-phenylglycolamides 2 with dicyclohexylcarbodiimide in boiling tetrachloromethane gives 3-substituted 1-alkoxyindolin-2-ones 3 in good yields.
Synthesen von Emodinaldehyd [1] / Synthesis of Emodine Aldehyde [1]
Authors: Thiem Joachim , Wessel Hans-Peter
Published: February 2015

9

By chromium trioxide oxidation and subsequent acid hydrolysis triacetyl emodine (3) was transferred to the aldehyde in a two-step synthesis. In a more favourable sequence 3 was reacted to the bromomethyl derivative 4 and this solvolyzed to the citreoroseine derivative 5. A second NBS reaction gave 8 which after acid hydrolysis led to emodine aldehyde (9). This five-step process proceeded without chromatographic separation in 27% overall yield.
Substitutionsreaktionen an 3,7-Dialkoxy-4H,8H-benzol(1,2-c:4,5-c′)diisoxazoI- 4,8-dionen und ihren Derivaten — synthetische Untersuchungen mit elektronenreichen Olefinen und anderen Nukleophilen / Substitution-Reactions at 3,7-Dialkoxy-4H,8H-benzol(1,2-c:4,5-c′)diisoxazole-4,8-diones and of its Derivatives — Synthetic Research with Electron-Rich Olefins and Nucleophiles
Authors: Neidlein Richard , Klotz Udo J.
Published: February 2015

3, 5, 8a-8d, 10

The syntheses of the compounds and 12a-12d by substitution-reactions, the different spectroscopic results are reported in detail.
1H and 13C NMR Spectroscopic Evidence for the Complexation of Potassium Cations by Cyclohexanedioxydiacetamides
Authors: Lin Whei Oh , Alt Helmut G.
Published: February 2015

The complexation of cyclohexanedioxydiacetamides by K+ cations may be studied by 1H and 13C NMR spectroscopy.
Two lithium tricyanomethanide compounds: syntheses and single-crystal structure determination of LiK[C(CN)3]2 and Li[C(CN)3]·½ (H3C)2CO
Authors: Reckeweg Olaf , DiSalvo Francis J.
Published: February 2015

The new compounds LiK[C(CN)3]2 and Li[C(CN)3]·½ (H3C)2CO were synthesized and their crystal structures were determined. Li[C(CN)3]·½ (H3C)2CO crystallizes in the orthorhombic space group Ima2 (no. 46) with the cell parameters a=794.97(14), b=1165.1(2) and c=1485.4(3) pm, while LiK[C(CN)3]2 adopts the monoclinic space group P21/c (no. 14) with the cell parameters a=1265.7(2), b=1068.0(2) and c=778.36(12) pm and the angle β=95.775(7)°. Single crystals of K[C(CN)3] were also acquired, and the crystal structure was refined more precisely than before corroborating earlier results.
Positively Charged Amino Acids at the SNAP-25 C Terminus Determine Fusion Rates, Fusion Pore Properties, and Energetics of Tight SNARE Complex Zippering
Authors: Fang Qinghua , Zhao Ying , Herbst Adam Drew , Kim Brian N. , Lindau Manfred
Published: February 2015

SNAP-25 is a Q-SNARE protein mediating exocytosis of neurosecretory vesicles including chromaffin granules. Previous results with a SNAP-25 construct lacking the nine C terminal residues (SNAP-25Δ9) showed changed fusion pore properties (Fang et al., 2008), suggesting a model for fusion pore mechanics that couple C terminal zipping of the SNARE complex to the opening of the fusion pore. The deleted fragment contains the positively charged residues R198 and K201, adjacent to layers 7 and 8 of the SNARE complex. To determine how fusion pore conductance and dynamics depend on these residues, single exocytotic events in bovine chromaffin cells expressing R198Q, R198E, K201Q, or K201E mutants were investigated by carbon fiber amperometry and cell-attached patch capacitance measurements. Coarse grain molecular dynamics simulations revealed spontaneous transitions between a loose and tightly zippered state at the SNARE complex C terminus. The SNAP-25 K201Q mutant showed no changes compared with SNAP-25 wild-type. However, K201E, R198Q, and R198E displayed reduced release frequencies, slower release kinetics, and prolonged fusion pore duration that were correlated with reduced probability to engage in the tightly zippered state. The results show that the positively charged amino acids at the SNAP-25 C terminus promote tight SNARE complex zippering and are required for high release frequency and rapid release in individual fusion events.
Identification of 12/15-Lipoxygenase as a Regulator of Axon Degeneration through High-Content Screening
Authors: Rudhard York , Sengupta Ghosh Arundhati , Lippert Beatrix , Böcker Alexander , Pedaran Mehdi , Krämer Joachim , Ngu Hai , Foreman Oded , Liu Yichin , Lewcock Joseph W.
Published: February 2015

Axon degeneration is a programed process that takes place during development, in response to neuronal injury, and as a component of neurodegenerative disease pathology, yet the molecular mechanisms that drive this process remain poorly defined. In this study, we have developed a semi-automated, 384-well format axon degeneration assay in rat dorsal root ganglion (DRG) neurons using a trophic factor withdrawal paradigm. Using this setup, we have screened a library of known drugs and bioactives to identify several previously unappreciated regulators of axon degeneration, including lipoxygenases. Multiple structurally distinct lipoxygenase inhibitors as well as mouse DRG neurons lacking expression of 12/15-lipoxygenase display protection of axons in this context. Retinal ganglion cell axons from 12/15-lipoxygenase-null mice were similarly protected from degeneration following nerve crush injury. Through additional mechanistic studies, we demonstrate that lipoxygenases act cell autonomously within neurons to regulate degeneration, and are required for mitochondrial permeabilization and caspase activation in the axon. These findings suggest that these enzymes may represent an attractive target for treatment of neuropathies and provide a potential mechanism for the neuroprotection observed in various settings following lipoxygenase inhibitor treatment.