bluuebunny/crossref_metadata_2025 huggingface dataset:
Die Stabilisierung von P(NH2)Hal2 (Hal = Cl, Br, I) und P(NHMe)2Cl als Komplexliganden / The Stabilisation of P(NH2)Hal2 (Hal = Cl, Br, I) and P(NHMe)2Cl as Complex Ligands
Authors: Maisch Hartmut
Published: February 2015

The phosphanes P(NH2)Hal2 and P(NHMe)2Cl are stabilised as ligands in (CO)5MoP(NH2)Hal2 [Hal = Cl (2), Br (3), I (4)] and (CO)5MoP(NHMe)2Cl (10) by reactions of (CO)5MoP(NH2)3 (1) with HHal or of (CO)5MoP(NHMe)3 (8) with HCl, respectively. 4 decomposes at room temperature and reacts with t-BuNH2 to give, (CO)5MOP(NH-t-BU)2NH2 (6). 1 and HI form (CO)5MoPI3. 3 can also be prepared from 2 with HBr, 4 from 2 and 3 with HBr and HI, respectively. The reactions of 2-4 with NR3 produce polymers, whereas the reaction of 3 with pyridine leads to (CO)5MoNC5H5. The mixtures (CO)5MoP(NHMe)Br2/(CO)5MoPBr3 and (CO)5MoP(NH-i-Pr)2Cl/(CO)5MoP(NH-i-Pr)Cl2 are isolated from reactions of 8 with HBr and of 9 with HI, and 9 reacts with HBr to give (CO)5MoPBr3. (CO)5MoP(NHMe)I2 is formed in small amounts by the reaction of 8 with HI, the main product is an insoluble solid, which is probably the impure intermediate [(CO)5MoP(NHMe)(NH2Me)2]2+2I-. Reaction of 10 with NEt3 leads to the formation of the dinuclear complex 12 in which the new diazadiphosphetidine [MeNHP-NMe]2 functions as a bridging ligand between two (CO)5Mo units.
Di- und trimeres Dimethylaminoisocyanat. Strukturen und Spektren / Di- and Trimeric Dimethylaminoisocyanate. Structures and Spectra
Authors: Zürn V. , Schwarz W. , Rozdzinski W. , Schmidt A.
Published: February 2015

N-Heterocyclic Compounds N,N-Dimethyl-N′,N′-bis(trimethylsilyl)hydrazine reacts with fluorophosgene to yield 5,5-dimethyl-3-dimethylamino-2,4-dioxo-5-azonia-imidazolidide (1). With phosgene, 1-methyl-2-chloroformyl-4-dimethylamino-1,2,4-triazolidine-3,5-dione (5) can be prepared. The thermal decomposition of N,N-dimethyl-N'-carbomethoxi-N′-trimethylsüyl-hydra-zine gives 1,3,5-tris(dimethylamino)-1,3,5-hexahydrotriazine-2,4,6-trione (2) and 1,2-dimethyl-4-dimethylamino-1,2,4-triazolidine-3,5-dione (3). 2 can also be prepared by thermal decomposition of N.N-dimethyl-N′-carbomethoxi-N′-fluoroformylhydrazine (4). The crystal and molecular structures of 1 and 2 were determined by X-ray analysis. The 1H NMR and vibrational data of 1-5 were communicated. The mass spectra of 1-3 were measured and discussed.
Zur Kristallchemie der Oxoplumbate(II), IV Einbau von Sr2+ in Pb9Al8O21 / Solid State Chemistry of Oxoplumbates(II), IV Incorporation of Sr2+ in Pb9Al8O21
Authors: Plötz K. B. , Müller-Buschbaum Hk.
Published: February 2015

In the new compound Pb9Al8O21 parts of Pb2+ are replaced by Sr2+. Isolated crystals of Pb8Pb0,6Sr0,4Al8O21 were investigated by single crystal work (space group Pa 3-T6
h; α = 13,26 Å; Z = 4). It can be shown, that the Pb2+ ion in the position 4b (posessing an untypical 2+6 coordination) is partly substituted by Sr2+.
Die Kristallstruktur von Dinatriumdi-μ-azido-tetraazido-bis- (hexamethy lentetramin) - dicuprat (II) - trihydrat, Na2[Cu2(N3)6(C6H12N4)2]·3 H2O, einem pentakoordinierten Kupfer(II)- Komplex / The Crystal Structure of Sodium Di-μ-azido-tetraazidobis(hexamethylenetetramine) dicuprate(II)-tri hydrate, Na2[Cu2(N3)6(C6H12N4)2]·3H2O, a Pentacoordinated Copper(II) Complex
Authors: Pickardt Joachim
Published: February 2015

By reaction of cupric chloride with sodium azide and hexamethylenetetramine in aqueous solution crystals of the title compound could be obtained. An X-ray analysis showed the compound to contain a dimeric cuprate(II) anion with terminal as well as bridging azido groups.
Einfluß der Adsorption auf die elektrochemische Reduktion von 1-Nitro-2-naphthol an Kohlenstoff-Faser-Elektroden / Influence of the Adsorption on the Electrochemical Reduction of 1-Nitro-2-naphthol at Carbon Fibre Electrodes
Authors: Theodoridou Elli , Karabinas Pantelis , Jannakoudakis Dimitrios
Published: February 2015

In the electrochemical reduction of 1-nitro-2-naphthol at carbon fibre electrodes an adsorption peak cathodic of the diffusion-controlled peak is obtained, as it happens in processes involving a strong adsorption of the reactant. This adsorption peak appears when the electrodes remain at positive potentials (+1V) in acidic solutions of the nitronaphthol and its interpretation is corroborated by its scan rate and concentration dependence.
Die Struktur des Na7Ga13-I und ein Konzept zur bindungsmäßigen Deutung / The Structure of Na7Ga13-I and its Characterization by a Bonding Scheme
Authors: Frank-Cordier Ursula , Cordier Gerhard , Schäfer Herbert
Published: February 2015

The new compound Na7Ga13-I crystallizes in the trigonal-rhombohedral system, space group R3m, with the constants a = 1496.5(3) pm, c = 3893(1) pm, c/o = 2.60.

The Ga atoms form Ga12 icosahedra and Ga15 clusters, connected to a threedimensional net. The arrangement of these clusters is related to the MgCu2 structure. The Na content of this compound correlates with the number of electrons necessary for a stable electron configuration in the Ga partial structure.

The BaAl4 type structure of NaGa4 has been confirmed by single crystal data
Darstellung und Kristallstruktur von Arsen(III)phosplior(V)oxid, AsPO4 / Preparation and Crystal Structure of Arsenic(III) Phosphorus(V) Oxide, AsPO4
Authors: Bodenstein Doris , Brehm Axel , Jones Peter G. , Schwarzmann Einhard , Sheldrick George M.
Published: February 2015

The compound ASPO4 was prepared from AS2O3 and P2O5 in a sealed tube at 673 K. The crystal structure, isostructural with AsO2, was refined to R = 0.021 [Pnma, a - 843.15(10), b = 502.29(10), c = 720.39(12) pm, Z = 4]. The structure consists of infinite layers. The arsenic(III) atoms are coordinated by three oxygen atoms at right angles; phosphorus(V) by four oxygens in the form of a distorted tetrahedron
Phasenbeziehungen im System As2Te3—AsI3 und die Kristallstruktur von As5Te7I / Phase Relations in the System As2Te3-AsI3 and the Crystal Structure of As5Te7I
Authors: Kniep Rüdiger
Published: February 2015

The system As2Te3-AsI3 is quasibinary and includes the intermediate phases As5Te7I and α-AsTeI with incongruent melting behaviour. The crystal structure of AssTe7I contains ribbons of condensed octahedral chains sharing common edges. Arsenic atoms are situated in the centres of the octahedra and - in a trigonal-pyramidal arrangement - at the borders of the ribbons. There are close relationships between the crystal structures of As2Te3 and AssTe7I as well as As5Te7I and α-AsTeI. The particular expansion of the As5Te7I one-phase region within the quasibinary system is discussed with respect to these structural relations
Metallorganische Verbindungen der Lanthanoiden, XTTT [1] Tris(di-f-butylarsin)-Derivate von Yttrium, Lanthan, Praseodym, Holmium, Erbium, Thulium und Lutetium / Organometallic Compounds of the Lanthanides, XIII [1] Tris(di-t-butylarsine) Derivatives of Yttrium, Lanthanum, Praseodymium, Holmium, Erbium, Thuhum, and Lutetium
Authors: Schumann Herbert , Frisch Georg-Michael
Published: February 2015

Lithium (di-t-butyl) arsenide reacts with the trichlorides of yttrium, lanthanum, praseodymium, holmium, erbium, thulium, and lutetium under elimination of lithium chloride and formation of the corresponding tris(di-t-butylarsine) derivatives
Trichonnethylphosphonsäuredihydrazid und 3.6-Bi8(trichlormethyl)-3.6-dioxo-1.2.4.5-tetraaza-3.6-diphosphacyclohexan / Trichloromethylphosphonic Acid Dihydrazide and 3,6-Bis(trichloromethyl)-3,6-dioxo-1,2,4,5-tetraaza-3,6-diphosphacyclohexane
Authors: Engelhardt Udo , Kirner Ingeborg
Published: February 2015

The title compounds are prepared from trichloromethylphosphonic acid dichloride and excess hydrazine hydrate, and from the dihydrazide and the dichloride in the presence of triethylamine, resp. They are characterized by elemental analysis, mass spectra, 1H and 31P NMR spectra, IR and Raman data. Thin layer chromatographic experiments show that in the raw material of the ring compound two isomers (probably cis- and trans-) are present, whereas in the recrystallized product only one isomer can be detected. Attempts of a preparative separation of isomers were unsuccessfull so far due to very low concentrations of the product with the slightly higher Rf. Single crystals of the isolated ring compound decompose on irradiation with X-rays
Strukturchemie von Verbindungen des pentakoordinierten Siliciums. Das Bis(ethylendioxy)methylsilan-Anion / Structural Studies of Pentacoordinate Silicon. The Bis(ethylenedioxy)methylsilane Anion
Authors: Schomburg Dietmar
Published: February 2015

Hexamethylendiammonium-bis(ethylenedioxy)methylsilane crystallizes in the hexagonal space group P6122, Z = 6 with a= 11.902(1), c = 30.148(4) A. The structure was refined to R - 0.041 using 2281 independent reflections. The geometry around the pentacoordinate silicon atom is between a trigonal bipyramid and a square pyramid. Oeq-Si-Oeq 136.0(1)°, Oax-Si-Oax 161.7(1)°. The Si-Oax bond lengths are 1.749(2) and 1.769(2) A, the Si-Oeq 1.711(2) and 1.735(2) A, Si-Ceq 1.876(3) A. The compound forms strong N-H ··· O hydrogen bonds between cation and anion. The cation lies on a crystallographic twofold axis
On the Extraction of Uranium from Sea Water by a Complexing Resin
Authors: Schwochau K. , Astheimer L. , Schenk H.-J. , Witte E. G.
Published: February 2015

A cross-linked polyacryl resin containing amidoxime or related functional groups is capable of concentrating uranium from natural sea water. The resin presents a uranium loading of more than 3000 ppm; moreover it has a higher selectivity, uptake rate, and attrition stability than hydrous titanium oxide
Funktionelle Trimethylphosphanderivate, XVII [1] Methyl-bis(dimethylphosphinomethyl)phosphan, (Me2PCH2)2PMe / Functional Derivatives of Trimethylphosphane, XVII [1] Methyl-bis(dimethylphosphinomethyl)phosphane, (Me2PCH2)2PMe
Authors: Karsch Hans H.
Published: February 2015

(Me2PCH2)2PMe (3) is obtained from MePCl2 (2a) or MeP(OPh)2 (2b) and LiCH2PMe2 (1). The oxides [Me2P(O)CH2]2PMe (4) and [Me2P(O)CH2]2P(O)Me (5), are formed on the reaction with air. Quaternisation with Mel gives the salts [(Me3PCH2)2PMe]I2 (6) and [(Me3PCH2)2PMe2]I3 (12). For comparison, also the isoelectronic (Me3SiCH2)2PMe (7), and (Me3SiCH2)2PtBu (8), are synthesized and transformed to their methylphosphonium salts 10 and 11. With CH2Br2, 3 forms the six-membered heterocycle [MeP(CH2PMe2)2CH2]Br2 (13a), which could not be isolated in a pure state, however. 3 may be metalated by LiBu: Li[Me2PCHP(Me)CH2PMe2] (15), is obtained, but a second metalation step could not be observed. The hydrolysis of 12 under unusual mild conditions (H2O or H2O/CH3OH) gives [Me2P(O)CH2PMe3]I (16), and [Me4P]I (17), as main products. Properties and NMR data of the new compounds are described.
Reactions of n-C5H5Co(CO)2 and n-Me3SiC5H4Co(CO)2 with (XCN)2 and X(CN)2 (X = S or Se)
Authors: Morán Moisés , Ibáñez Augusto
Published: February 2015

The pseudohalogens (XCN)2 (X = S or Se) react with n-C5H5Co(CO)2 and n-Me3SiC5H4Co(CO)2 with formation of the 18 electron complexes, RCo(CO)(XCN)2 (R = n-C5H5 or n-Me3SiC5H4). By reactions with X(CN)2 (X = S or Se), the cyclopentadienyl cobalt dicarbonyls are transformed into the mixed complexes, RCo(CO)(CN)(XVN) (R = n-C5H5 or n-Me3SiC5H4. All the compounds are characterized by elemental analysis, IR, electronic and 1H NMR spectra. The thiocyanogen derivatives undergo linkage isomerism (N→S) in polar solvents.
Beiträge zur Chemie des Phosphors, 109 [1] t-Bu6lAs2P6 - der erste Phosphor-Arsen-Polycyclus / Contributions to the Chemistry of Phosphorus, 109 [1] t-Bu6As2P6 - the First Phosphorus Arsenic Polycycle
Authors: Baudler Marianne , Aktalay Yusuf , Heinlein Thomas , Tebbe Karl-Friedrich
Published: February 2015

The first phosphorus arsenic polycycle t-Bu6As2P6 (1) was synthesized by dehalogenation of a 3:1 mixture of tert-butyldichlorophosphane and phosphorus trichloride using magnesium. 1 has been characterized by spectroscopic methods and by a crystal structure analysis having the t-Bu6Ps-analogous 2,2′,3,3′,4,4′-hexa-tert-butyl-l′-diarsa-2,2′,3,3′,4,4′-hexaphospha- bicyclobutane structure. In solution, the rotation around the exocyclic As-As bond is restricted already at room temperature.

1 crystallizes triclinically in the space group PT (No. 2) with a = 919.4 pm, b = 924.3 pm, c = 1171.7 pm, a = 97.21°, β = 102.98°, γ = 112.75°, and Z = 1 formula unit (V = 0.8694 nm3, Dx = 1.295 Mg · m-3). The crystal structure has been solved by 'direct methods' and refined to R = 0.048 with 2131 observed reflections. The molecule with symmetry C1 consists of two trans oriented and slightly folded four-membered P3As rings. The exocyclic bond length (d(As-As) = 244.1 pm) as well as the average endocyclic bond lengths d̅(As-P) = 235.6 pm; 3d̅(P-P) = 222.6 pm) are normal. The arrangement of the tert-butyl substituents with average bond lengths d̅(P-C) = 189.9 pm and d̅(C-C) = 1 5 2 . 5 p m is all-trans.
Darstellung und Reaktionen von S-Perfluoralkyl-Schwefelmonofluoridimiden / Preparation and Reactions of S-Perfluoroalkyl Sulphurmonofluoride Imides
Authors: Lensch Cornelia , Glemser Oskar
Published: February 2015

S-Perfluoroalkyl-N-pentafluorosulphanyl sulphurmonofluoride imides

(Rt - CF3 (1a) , t-C3F7 (1b)) are prepared by the reaction of NSF3 with appropriate sulphurtrifluoride derivatives. The fluorine bonded to sulphur(IV) in 1a and 1b is substituted by PCl5 to give sulphurmonochloride imides

(Rt = CF3 (2a), i-C3F7 (2b)). The chlorine in 2a and 2b can be exchanged by reaction with suitable silver(I) and mercury(II) salts.
Ureadiid-Derivate von Mangan(I)-und Rhemum(I)-carbonylen / Ureadiide Derivatives of Manganese (I) and Rhenium (I) Carbonyls
Authors: Dannecker Walter , Müller Hans Werner
Published: February 2015

The synthesis of the ureadiido compounds M′[M(CO)nL] (1-5; M′ = Li, K; M = Mn, Re; n = 5,4), in which the ureadiide ions act as monodentate and bidentate ligands, resp., is described. The force constants of the CO-stretching vibrations are calculated and the σ-donor and π-acceptor properties of ureadiide ligands are discussed.
Zur Elektrochemie von Metall(O)-Verbindungen, V [1] Reaktionen von Diazadien-Metall(VIb)-carbonylkationen und -anionen / Electrochemistry of Metal(O) Compounds, V [1] Reactions of Diazadiene Metal(VIb) Carbonyl Cations and Anions
Authors: Dieck Heindirk torn , Kühl Ewald
Published: February 2015

Carbonyl complexes of chromium, molybdenum and tungsten of the type DAD M(CO)4 with DAD - diazadiene (R-N=CR′-CR′=NR) are shown by cyclic voltammetry to undergo electron transfer reactions to [DAD M(CO)4]+ and [DAD M(CO)4]-. The rate of subsequent chemical reactions with nucleophiles or by loss of ligands depend on the sol-vent, the metal and the ligands' electronic and steric properties. Chromium(+I) is more readily stabilized than Mo(+I) or W(-I) while the opposite is true for the stability of the anions formed. The dimerisation of a low-coordinate species DAD Mo(CO)3 from the reduction of DAD Mo(CO)3(CH3CN) is detected electrochemically. The stabilization of oxidation states +1 and -I is briefly discussed in view of the DAD ligand properties.
Acyclische Liganden mit fixierter Koordinationsgeometrie, 1:2-Komplexe von Cobalt(II) mit den Anionen von 2.2′-Dihydroxydiphenyloxid und -sulfid -Kristall-und Molekülstruktur von Natrium-bis[diphenylsulfid-2.2′ -diolato(2-)]cobaltat(II>- Aceton-Wasser (1/2/1) / Acyclic Ligands with Fixed Coordination Geometry, I 1:2 Complexes of Cobalt(II) with the Anions of 2,2′-Dihyydroxydiphenyloxide and -sulfide - Crystal and Molecular Structure of Sodium bis[diphenylsulfide-2,2′-diolato(2-)]cobaltate(II)- Acetone-Water (1/2/1)
Authors: Müller Hartmut , Holzmann Arno , Hinrichs Winfried , Klar Günter
Published: February 2015

The synthesis of bis[diphenylchalcogenide-2,2′-diolate(2-)]-cobaltate(II) compounds is described. In these complexes diphenyloxide-2,2′-diolate acts as a bidentate, diphenylsulfide- 2,2′-diolate as a tridentate chelating ligand leading to tetrahedral or octahedral coordinated cobalt(II), resp.

An X-ray analysis of sodium bis[diphenylsulfide-2,2′-diolate(2-)]cobaltate(II)-acetonewater (1/2/1) shows the ligands to occupy fac-, their sulfur atoms cis-positions. The Co-0 distances (average 204.5 pm) are in the normal range while the C-S distances (average 248.5 pm) are longer than usually found indicating weaker bonds to sulfur than to oxygen.
Reactions of OH Radicals with Acetylacetone in Aqueous Solution. A Pulse Radiolysis and Electron Spin Resonance Study
Authors: Broszkiewicz R. K. , Söylemez T. , Schulte-Frohlinde D.
Published: February 2015

Pulse radiolysis experiments monitoring optical absorbance as well as conductivity and in-situ ESR radiolysis studies show that the OH radical reacts with the enol (k=8.6 x 109 M-1 s-1) and the enolate (k = 7.4 X 109 M-1 s-1) forms of acetylacetone by addition to the C = C double bond in aqueous N2O saturated solution. The OH reaction with enol leads to equal amounts of two radicals, CH3COCHOHCOHCH3 (2) and CH3COCHC(OH)2CH3 (4), as determined by scavenger reactions. At pH less than 1 the radical CH3COCHCOCH3 (1) is observed by ESR spectroscopy showing that radical 2 and/or 4 eliminate water by proton catalyzed reactions. Under alkaline condition the OH adducts to the enolate eliminate OH -with rate constants larger than 105 s-1 leading to radical 1. G(OH-) is determined to be 5.6 showing that addition is the main reaction of OH with enolate. To a much smaller degree the OH radical is proposed to abstract an H atom from that CH3 group which is attached to the C -C double bond in enol and enolate, producing substituted allyl radicals which absorb in the visible region. The reaction of OH with the keto form has not been observed indicating that the rate constant of this reaction is significantly smaller than those with enol and enolate.
Does a quasi-Thermal retro-Diels-Alder Decomposition Exist in Mass Spectrometry ? [1]
Authors: Bukovits G. J. , Budzikiewicz H.
Published: February 2015

Evidence is produced to the effect that in mass spectrometry a quasi-thermal retro-Diels-Alder decomposition does not occur. This reaction has to be triggered by the positive charge in the molecule.
Reduktion von Butyl-und Phenylantimon(III)bromiden sowie von t-Butylantimon(III)chloriden mit Magnesium in Gegenwart von Trimethylchlorsilan: Konkurrenz von Sb-Sb-und Sb-Si-Verknüpfung / Reduction of Butyl-and Phenylantimony(III) Bromides and of t-Butylantimony(III) Chlorides with Magnesium in the Presence of Trimethylchlorosilane: Competition of Sb-Sb and Sb-Si Coupling
Authors: Breunig Hans Joachim , Severengiz Tevfik
Published: February 2015

Butylantimony(III) bromides react with Mg in tetrahydrofuran (THF) even in presence of Me3SiCl exclusively with Sb-Sb-coupling: Starting from Bu2SbBr, Bu2SbSbBu2 is formed and BuSbBr2 is reduced to (BuSb)x. Sb-Si-coupling dominates in the reactions of Ph2SbBr or t-Bu2SbCl with Mg/Me3SiCl/THF yielding Ph2SbSiMe3 or t-Bu2SbSiMe3.

Both Sb-Sb- and Sb-Si-coupling reactions are observed, when PhSbBr2 reacts with Mg and Me3SiCl yielding PhSb(SiMe3)2 and (PhSb)x. The same reactants can also form the distibanes Ph2(SiMe3)2Sb2 and Ph(SiMe3)3Sb2. The reaction of t-BuSbCl2 with Mg/Me3SiCl yields the stibines t-BuSb(SiMe3)2 and Sb(SiMe3)3 together with (t-BuSb)4. In the reactions of t-BuSbCl2 or PhSbBr2 the ratio of Sb-Sb- and Sb-Si-coupling can be strongly influenced by using different reaction conditions.
Darstellung, Eigenschaften und Reaktivität von 2-, 3- und 4-Chloracyl(diphenyl)phosphanoxiden / Preparation, Properties and Reactivity of 2-, 3- and 4-Chloroacyl(diphenyl)phosphane Oxides
Authors: Lindner Ekkehard , Steinwand Michael
Published: February 2015

The highly reactive chloroacyl(diphenyl)phosphane oxides RC(O)-P(O)Ph2 (2a-d, g) [R = HCCl2 (a), CCl3 (b), CH3CHCl (c), CH3CCl2 (d), ClCH2CH2 (e), CH3CHClCH2 (f), ClCH2(CH2)2 (g)] are obtained by oxidation of the thermally labile chloroacyl(diphenyl)- phosphanes RC(O)-PPh2 (1a-d, g) with molecular oxygen in ether at low temperatures. While hydrolysis leads to a complete decomposition of 2a-d, g, the oxidation of 1a, c, e-g with oxygen in the presence of HP(O)Ph2 yields the diphosphorylated alcohols RC[P(O)Ph2]2OH (3a, c, e-g). 3e, f can be interpreted as trapping products of the not isolable oxides 2e, f. In tetrachloroethene a partial transformation of 3a into the phosphinate RC[P(O)Ph2][OP(O)Ph2]H can be observed which can be followed 31P{1H}-NMR spectroscopically. In solution the alcohols 3c, e-g decompose to give HP(O)Ph2 and the corresponding phosphane oxides 2c, e-g.
11B- und 13C-NMR-Spektroskopie von nido-Hexaalkyl-2.3.4.5-tetracarbahexaboranen(6) / 11B- und 13C-NMR Spectroscopy of nido-Hexaalkyl-2,3,4,5-tetracarbahexaboranes(6)
Authors: Wrackmeyer Bernd
Published: February 2015

11B and 13C NMR data of peralkylated nido-2,3,4,5-tetracarbahexaboranes(6) are reported. Application of selective heteronuclear triple resonance experiments 13C{1H,11B} enables to assign the structures of various isomers. The magnitude of the coupling constants 1J(11B11B), 1J(13C11B) and 1J(13C13C) is in accord with expectations based on the conception of bonding in carboranes. The comparison of δ11B and δ13C data of the nido- 2,3,4,5-tetracarboranes(6) with δ13C-data of corresponding non-classical carbocations shows the influence of charge upon the nuclear shielding of carbon in the latter.
Darstellung, Struktur und elektrische Eigenschaften der Phase CaCu4As2 / Preparation, Crystal Structure and Electrical Conductivity of CaCu4As2
Authors: Pfisterer Martin , Nagorsen Günter
Published: February 2015

Investigations in the system Ca-Cu-As resulted in the discovery of CaCu4As2. The phase crystallizes in a rhombohedral structure (Trigonal axes: a = 417.3(6) pm, c = 2262(3) pm, space group R3̅m). The conductivity varies from 47 to 89 (Ωcm)-1 having a minimum at 250 K.
Leitfähige S-N-Polymere mit p-Phenylengruppen / Conductive S-N Polymers with p-Phenylen Groups
Authors: Scherer Otto J. , Wolmershäuser Gotthelf , Jotter Reimund
Published: February 2015

Silylated diamines and diimines of type 13, 14 and 9-11 react with sulfur chlorine compounds SCl2, SOCl2, 8 and 12 to give 1-7 as linear S-N polymers with p-phenylen groups. Subsequent doping with acceptors (I2, Br2, AsF5) increases conductivity of 1-5 to ca. 10-4Ω-1cm-1.
The Structure of 5,10-Dihydro-5,10-diethylphenaziniumyl (E2P+)-2,2′-(2,5-cyclohexadiene-1,4-diylidene)-bispropanedinitrilate(TCNQ-) and its Difference to the Phenazine Doped Species E2P-P-(TCNQ)2 (P = Phenazine)
Authors: Dietz K. , Endres H. , Keller H. J. , Moroni W. , Wehe D.
Published: February 2015

Phenazine free E2P-TCNQ, C28H22N6, Mr = 442.53 is monoclinic, P21/c, a = 10.875(3), b = 14.679(4), c = 14.526(2) Å, β = 90.90(2)°, V = 2321.9 Å3 , Z = 4, dc = 1.27 Mgm-3 , the compound doped with 50% phenazine, E2P-P-(TCNQ)2 C52H34N12, Mr = 826.93, is triclinic, P1̅, a = 7.739(3), b = 15.899(6), c = 17.037(7) Å, α = 83.44(3), β = 88.34(3), γ = 83.19(3)°, V = 2067.7 Å, Z = 2, dc= 1.33 Mgm-3. E2P-TCNQ was refined to R = 0.066 for 1880 reflections. It consists of planar TCNQ anions and bent E2P cations (dihedral angle 17.7° along the line N-N) arranged in regular mixed stacks along c. The structure of E2P-P-(TCNQ)2 could be solved principally, but did not refine well (R = 0.165 for 1206 reflections). Regular segregated stacks of the phenazine and the TCNQ moieties are formed, and along the cationic stack the E2P+ cations and the neutral phenazine molecules alternate.
Der Einfluß von Atropisomerie und chiralem Zentrum auf die biologische Aktivität des Metolachlor / The Influence of Atropisomerism and Chiral Centre on the Biological Activity of Metolachlor
Authors: Moser Hans , Rihs Grety , Sauter Hanspeter
Published: February 2015

The four stereoisomers of the grass herbicide Metolachlor, the isomerism of which is based on a combination of a chiral centre and a chiral axis, were prepared, and their absolute configurations determined by X-ray analysis. The synthesis was achieved by using optically active starting materials and new optically active carbamates as intermediates. The herbicidal activity is mainly influenced by the chiral centre, the S-isomers being the most active ones.
Transition Metal Complexes of Diazenes, XVII [1]. Reactions of 1,2-Diazetines and 1,2-Diazetine-N-oxides with Iron Carbonyls
Authors: Albini A. , Kisch H. , Krüger C. , Chiang An-Pei
Published: February 2015

Enneacarbonyldiiron reacts with 3,3,4,4-tetramethyl-1,2-diazetine (L) or its mono-N-oxide (L′) to form complexes (L)Fe(CO)4 (3), (L)Fe2(CO)7 (4), (L)Fe2(CO)6 (5), or (L′)Fe(CO)4 (6), and small amounts of deoxygenated 4 and 5, respectively. Formation and stability of the complexes is compared with those of ligands with smaller and larger ring sizes and discussed in terms of the electronic properties of the ligand lone-pair Orbitals. The molecular structure of 4 is established by X-ray analysis.
Zum Cycloadditionsverhalten von bis(trifluormethyl)substituierten Nitril-yliden [1]. Positionsselektivität und Regiochemie bei Abfangreaktionen mit Heterokumulenen / Cycloaddition Behaviour of Bis(trifluoromethyl) Substituted Nitrile Ylides [1]. Site Selectivity and Regiochemistry of Trapping Reactions with Heterocumulenes
Authors: Burger Klaus , Goth Herbert , Daltrozzo Ewald
Published: February 2015

2,2,2-Trimethoxy-3,3-bis(trifluoromethyl)-2,2-dihydro-1,4,2-oxazaphosphol-4-enes on thermolysis undergo a 1,3-dipolar cycloreversion reaction with formation of bis(trifluoromethyl) substituted nitrile ylides and trimethyl phosphate. The nitrile ylides are trapped by N-sulfinyl aniline, phenyl isocyanate, phenyl isothiocyanate, diphenyl ketene, and carbon disulfide. Site selectivity and regiochemistry of the [3 + 2]cycloaddition reactions are described. The results are compared with those obtained from [3 + 2]cycloaddition reactions of nitrile imines, nitrile oxides, alkyl, and aryl substituted nitrile ylides with heterocumulenes.
Reaktionen von Phenanthren mit Stickstoffdioxid in ultraviolettem Licht / Reactions of Phenanthrenes with Nitrogendioxid in UV Light
Authors: Barlas H. , Parlar H. , Kotzias D. , Körte F.
Published: February 2015

The compounds 2-7 were isolated from solutions of phenanthrene (1) and nitrogendi-oxide in carbon tetrachloride after irradiation with UV light having long wavelengths (λ > 290 nm). With the help of spectroscopical methods the proposed structures are derived. Radical mechanisms are proposed for these reactions.
Die Synthese von 1-substituierten 4.4.4-Trichlor-Δ2 -trans-butenen / The Synthesis of 1-Substituted 4,4,4-Trichloro-Δ2 -trans-butenes
Authors: Seidel Peter , Ugi Ivar
Published: February 2015

Numerous 1-substituted 4,4,4-trichloro-Δ2-butenes are prepared from the 1-substituted 2-bromo-4,4,4-trichloro-butanes by HBr-elimination and by substitution reactions.
Untersuchungen zur Charakterisierung des Prochamazulens Matrizin aus Matricaria chamomilla L. / Studies on the Characterization of the Chamazulene Precursor Matricine from Matricaria chamomilla L.
Authors: Flaskamp Elmar , Zimmermann Gottfried , Nonnenmacher Gerhard , Isaac Otto
Published: February 2015

The relative configuration of the thermolabile chamazulene precursor matricine has been established by NMR spectrometric studies.

The NMR spectral data prove to be consistent with the well-known structure of the chamomile component. On the basis of our results the levorotatory natural substance moreover can be specified stereochemically as (−)-(3S*, 3aR*, 4S*, 9R*, 9aS*, 9bS*)-4-acetoxy-2,3,3a,4,5,9,9a,9b-octahydro-9-hydroxy-3,6,9-trimethylazuleno[4,5-b]furan-2-one.
Beiträge zur Strukturchemie phosphorhaltiger Ketten und Ringe, V [1] Die Molekül- und Kristallstruktur des 1.2.3.4-Tetra-tert-butyl-1.4-bis(trimethylsilyl)tetraphosphans, Me3Si-(t-BuP)4-SiMe3 / Structural Chemistry of Phosphorus-Containing Chains and Rings, V [1] Molecular and Crystal Structure of 1,2,3,4-Tetra-tert-butyl-1,4-bis(trimethylsilyl)tetraphosphane, (H3C)3Si-(t-BuP)4-Si(CH3)3
Authors: Tebbe Karl-Friedrich , Fröhlich Roland
Published: February 2015

The compound 1,2,3,4-tetra-tert-butyl-1,4-bis(trimethylsilyl)tetraphosphane, Me3Si-(t-BuP)4-SiMe3, C22H54P4Si2, crystallizes monoclinically in the space group P21/n (No. 14) with a = 889.9 pm, b = 2292.8 pm, c = 1568.0 pm, β = 94.14° and Z = 4 formula units.

The molecule forms a twisted Si-P4-Si-chain with two kinds of P-P-bonds. The atoms neighbouring the silicium atoms take part in bonds of length d̄(P-P) = 218.8 pm, whereas the central bond d̄(P-P) = 221.4 pm is much longer. A special feature of the structure is a short contact d̄(P-P) = 345.6 pm. Therefore, the inner region of the molecule has the shape of a nearly planar trapezium of the four phosphorus atoms. The periphery of the molecule is as expected. The average bond lengths are d̄(P-Si) = 228.5 pm, d̄(P-C) - 190.2 pm, d̄(Si-C) = 186.6 pm, d̄(C-C) = 151.8 pm and d̄(C-H) = 94 pm
Untersuchungen an Polyhalogeniden, V [1] Darstellung und Kristallstruktur des Tetrammin-palladium(II)-oktaiodids, [Pd(NH3)4]I8 / Studies on the Polyhalides, V [1] Preparation and Crystal Structure of [Pd(NH3)4]l8
Authors: Tebbe Karl-Friedrich , Freckmann Bernhard
Published: February 2015

The new compound [Pd(NH3)4]l8 crystallizes monoclinically in the space group P21/m with a = 959.0 pm, b = 835.4 pm, c = 1301.1 pm, β = 103.37° and Z = 2 formula units. The crystal structure has been solved by 'direct methods' and refined to R = 0.057 with 1357 observed reflections.

The structure consists of quadratically coordinated cations [Pd(NH3)4]2+ and planar, Z-shaped and completely ordered octaiodide anions I8
2-. According to the sequence of interatomic distances d(I-I) = 295.0 pm, 289.9 pm, 336.2 pm, 279.1 pm, 327.0 pm, 339.3 pm, 273.8 pm the anions may be described as [I3- • I2 • (I- • I2)]- The iodide-iodine sides (I- • I2) are joined with the distance d(I---I) = 364.1 pm to a slightly bent triiodide chain being part of an octaiodide ribbon 1
∞[I8
2-]- Next contact spacings between neighboring anions start at d(I---I) = 403.7 pm
On the Crystal Structure of HgZn3
Authors: Pušelj M. , Ban Z. , Drašner A.
Published: February 2015

The crystal structure of the intermetallic phase HgZn3 was determined using X-ray single crystal and powder diffraction methods. The phase belongs to the orthorhombic system, most probable space group being Cmc21, and appears to be isostructural with β'-Cu3Ti. Under standard preparative conditions a statistical distribution of both atomic species was observed
Phosphinsubstituierte Chelatliganden, IV [1] Neue Diphenylphosphinoformamid-Komplexe des Mangans und Eisens / Phosphine Substituted Chelate Ligands, IV [1] New Diphenylphosphino Formamide Complexes of Manganese and Iron
Authors: Kunze Udo , Antoniadis Antonios
Published: February 2015

The phosphino and (thio)phosphoryl formamides 1a, b, 2a-c, 3a, b, 4a, b which were partially unknown are synthesized by various methods, and their reactions with carbonylmetal halides of manganese and iron are described. The formation of the P,N- and S,N coordinate chelate complexes, (CO)4MnL (5 a, 8a), is limited to the N-phenyl derivatives la and 4a. With L = 2a, b, the unidentate P-coordination predominates. Thus, the carbonylmetal halide complexes cis-(CO)4Mn(X)L (6a, b: X = CI, 7a, b: X = Br) and η5-C5H5(CO)Fe(X)L (9a, b: X = I, 10a, b: X = Br) are obtained. Due to the low stability of the formamide complexes, their formation is always accompanied by isocyanate elimination as a side-reaction
Schwefel-Stickstoff-Verbindungen, IX [1] Darstellung und spektroskopische Charakterisierung einiger Schwefeldiimide von Elementen der 4. Hauptgruppe / Sulfur-Nitrogen Compounds, IX [1] Preparation and Spectroscopical Characterization of Some Sulfur Diimines with Elements of Main Group IV
Authors: Brands G. , Golloch A.
Published: February 2015

Compounds of the sulfur(IV) diimines with elements of the main group IVb were prepared. Spectroscopic behaviour and the scope and limitations of preparing sulfurdiimines from amines and N3S3CI3 are discussed
Darstellung und Schwingungsspektren von Chloro-Bromo-Platinaten(IV) einschließlich der Stereoisomeren / Preparation and Vibrational Spectra of Chloro-Bromo-Platinates(IV) Including Stereoisomers
Authors: Preetz W. , Rimkus G.
Published: February 2015

The mixed chloro-bromo complexes [PtClnBr6-n]2-, n = 1-5, are separated by ion exchange chromatography on diethylaminoethylcellulose. The separation of corresponding stereoisomers for n = 2, 3, 4 is not possible. Due to the stronger trans-effect of Br compared with Cl, on treatment of [PtBrß]2- with Cl- in the presence of Br2 nearly pure cis-isomers, and by reaction of [PtClsBr]2- and cis-fPtC^Bro]2- with Br~/Br2 completely pure transisomers are formed. The stereoselectivity of the successive ligand exchange reactions is better than in corresponding series of Re, Os and Ir. The highly resolved vibrational spectra allow the distinction of the mixed ligand complexes as well as the estimation of purity of the isomers. All allowed stretching frequencies are observed and assigned according to point groups D4h, C4V, C3V and C2V. Especially in the ν(Pt-Br) region it is possible to distinguish bands arising either from symmetric Br-Pt-Br or asymmetric Cl-Pt-Br axes. The UV/VIS spectra exhibit systematic hypsochromic shifts on the successive exchange of Br-ligands by Cl. A critical discussion of the literature concerning chloro-bromo-platinates- (IV) shows the importance of effective separation processes for the isolation of pure mixed ligand complexes
Synthese und Reaktivität von Silicium-Übergangsmetallkomplexen, XIV [1] Umsetzung von Cp(CO)2Fe-substituierten Silieium-Wasserstoff-Verbindungen mit DicobaJtoctacarbonyl: Synthese von Siliciumverbindungen mit zwei, drei und vier Übergangsmetall -Liganden / Synthesis and Reactivity of Silicon Transition Metal Complexes, XIV [1] Reaction of Cp(CO)2Fe-Substituted Silanes with Dicobaltoctacarbonyl: Synthesis of Silicon Compounds with Two, Three and Four Transition Metal Ligands
Authors: Malisch Wolfgang , Wekel Hans-Ulrich , Grob Irmgard , Köhler Frank H.
Published: February 2015

The reaction of Cp(CO)2Fe-SiHCl2 with Co2(CO)8 yields the heteronuclear complex Cp(CO)2Fe-SiCl2-Co(CO)4 (1) and HCo(CO)4.1 is degradated by AgBF4 to Cp(CO)2Fe-SiF3. PMe3 transforms 1 to Cp(CO)2Fe-SiCl2-Co(CO)3PMe3 (2). LnM-SiH2Me reacts with Co2(CO)8 to give LnM-SiMe-Co2(CO)7 [LnM = Cp(CO)2Fe (3a), Cp(CO)2PMe3W (3b)]. Starting with Cp(CO)2Fe-SiH3, μ3-Cp(CO)2Fe-SiCo3(CO)9 (4), the second example of a μ3-metallosilylidine tricobalt cluster is obtained in high yield, which is cleaved by acetic acid to Cp(C0)2Fe-Si[OC(O)Me]3 (5). The composition and structure of the silicon transition metal complexes 1-5 is proved by NMR, IR and mass spectroscopy. 29Si NMR shifts are determined for the first time for a tri- and tetra-metalated silicon species
Spektroskopische Untersuchungen an Cyclopentadienyl-dinitrosylvanadium-Komplexen CpV(NO)2L (L = Lewis-Base) / Spectroscopic Studies with Cyclopentadienyl Dinitrosylvanadium Complexes CpV(NO)2L (L = Lewis Base)
Authors: Herberhold Max , Trampisch Herbert
Published: February 2015

Displacement of the CO ligand in CpV(NO)2CO (Cp = η5-cyclopentadienyl) by various Lewis bases (L) in solution leads to a series of (28) complexes CpV(NO)2L which were characterised by the 51V NMR chemical shift, the 13C and 1H NMR chemical shifts of the cyclopentadienyl ring, and by the NO stretching frequencies of the two nitrosyl ligands. The chemical shift δ(51V) varies over the range of ca. -1300 and -500 ppm depending on the nature of L, whereas δ(13C) of the cyclopentadienyl ring varies only between 98 and 102 ppm. The shielding of the 51V and 13C nuclei decreases as the electronegativity of the ligand atom bound to the metal increases in the order P <S <N <O
G. Schmid-R. Greese • Tetraschwefeltetraimid als Ligand in Übergangsmetallkomplexen / Tetrasulfur Tetraimide as Ligand in Transition Metal Complexes
Authors: Schmid Günter , Greese Richard , Boese R.
Published: February 2015

Tetrasulfur tetraimide reacts with (THF)M(CO)5 (M = Cr, W) to form isolable complexes of the type (S4N4H4)M(CO)5 (1) and (S4N4H4)[M(CO)5]2 (2) respectively, 1H NMR and X-ray investigations show the metal to be coordinated to sulfur atoms. In solution partially dissociation of M(CO)5 moieties is observed leading to different equilibria. They are studied by 1H NMR
Lifetime of Singlet Oxygen and Quenching by NaN3 in Mixed Solvents
Authors: Miyoshi N. , Ueda M. , Fuke K. , Tanimoto Y. , Itoh M. , Tomita G.
Published: February 2015

Singlet oxygen was generated by the photosensitization of erythrosine. The lifetime of singlet oxygen and the quenching rate constant for singlet oxygen by NaN3 were measured by a thermal lensing method in MeOH-H2O mixed solvents. The reciprocal of the lifetime increased linearly with the increase of the H2O mole fraction. Semi-log plot of the quenching constant against the reciprocal of the solvent polarity exhibited a linear relation. The quenching of the singlet oxygen by NaN3 may proceed through a partial charge-transfer intermediate. The activation energy for the quenching reaction of N3
- + 1O2 →[N3·1O2
-] increased with the increase of the solvent polarity. The lifetime was also measured in MeOH-ethyleneglycol mixed solvents, and its relation with viscosity was obtained
Preparation and Structure of Zinc(II) Complexes of Purine and 7-Azaindole
Authors: Sheldrick William S.
Published: February 2015

Trichloro(purinium)zinc(II) (1) and dichloro-bis-(7-azaindole)zinc(II) (2) have been prepared from respectively 1:1 (in acid solution) and 2:1 aqueous solutions of the parent base and zinc(II) chloride. In the latter case the salt di-[7-azaindolium]zinc(II) tetrachloride (3) is isolated under acid conditions. The structures of 1-3 have been established by X-ray structural analyses. Zinc coordinates the purine nitrogen N(7) in 1 and N(3) of 7-azaindole in 2. N(l) is protonated in 1. The bond length distribution of the cations 3 suggests a significant contribution from a resonance form in which N(9) carries the positive charge
Aminomethylierung von 3-Amino-inden-1-onen / Aminomethylation of 3-Amino-indene-1-ones
Authors: Möhrle Hans , Novak Hans-Joachim
Published: February 2015

N-mono- and N-di-substituted 3-amino-indene-l-ones with free secondary amines yield no Mannich products, but the corresponding 2,2'-methylene biscompounds. C-Aminomethylation is possible with hydrochlorides of secondary amines, aminals or methylene iminium salts. With primary amines and two equivalents of formaldehyde indenopyrimidines are available
Characterization of Alcohol Solvents by the Empirical Polarity Parameters AN, Z, and ET(30)
Authors: Elias Horst , Dreher Michael , Neitzel Sabine , Volz Harald
Published: February 2015

The acceptor number AN and the polarity parameters Z and ET(30) were determined for a series of alcohols applied as media in the study of kinetic solvent effects. The alcohols thus characterized are methanol, ethanol, 1-propanol, 1-butanol, 2-butanol, 2-methyl-2-butanol, 3-pentanol, 2-chloroethanol, 2-methoxyethanol, 2-phenylethanol, 2-cyanoethanol, benzyl alcohol, 3-ethyl-3-pentanol, 2,4-dimethyl-3-pentanol, and 3-ethyl-2,4-dimetliyl-3-pentanol. In addition, AN was determined for 1,2-dichloroethane and Z for the binary solvent mixtures methanol/2-methyl-2-butanol, ethanol/2,2,2-trifluoroethanol. and methanol/pyridine. The data obtained are correlated and the parameters AN, Z, and ET(30) are critically compared.
P(C6H5)4[VOBr4]: Synthese, IR-Spektrum und Kristallstruktur / P(C6H5)4[VOBr4]: Synthesis, IR Spectrum and Crystal Structure
Authors: Müller Ulrich , Shihada Abdel-Fatah , Dehnicke Kurt
Published: February 2015

PPh4[VOBr4] was prepared by the reaction of PPh4Br with VOBr3 in CH2Br2 solu-tion. The structure of the dark violet crystals was determined with X-ray diffraction. PPh4[VOBr4] crystallizes in the space group P4/n with the lattice constants a = 1275.9 and c = 784.5 pm with two formula units per unit cell. The structure type corresponds to the frequently encountered AsPh4[RuNCl4] type. The VOBr4
- ion forms a square pyramid; the V = O bond has a length of 155 pm. In the IR spectrum, the V -O stretching vibration appears at 922 cm-1 .
Oxamide Oxime Complexes: The Structure of the Complex Bis ( oxamide - oximato )nickel( II) - Hydrogen Chloride - Water, and the Characterization of the Analogous Platinum(II) Complex
Authors: Entires Helmut
Published: February 2015

[Ni(C2H5N4O2)2] · HCl · H2O, C4H10N8NiO4 · HCl · H2O, forms triclinic crystals, Mr = 347.36, P1̄, a = 7.219(2), b = 7.316(1), c = 11.797(3) Å, α = 73.89(2), β = 86.37(2), γ = 85.71(2)°, V = 596 Å3 , Z = 2, dc = 1.93 Mgm-3 ; final Rw = 0.028 for 1957 reflections. The planar complex molecules form equidistant stacks along b, with the molecular planes inclined at ~29° to the stacking axis. Molecules of adjacent stacks are linked along a by an intermolecular H bridge coexistins with the usual intramolecular H bridges. The analogous Pt complex, C4H10N8O4Pt · HCl · H2O, Mr = 483.74, a = 6.480(4), b = 16.115(5), c = 12.194(9) Å, β = 101.27(4)°, V = 1249 Å3 , Z = 4, dc = 2.57 Mgm-3 , P21/a, crystallizes in a columnar structure with a Pt-Pt separation of ~a/2 ≈ 3.24 Å. Due to twinning, faking orthorhombic symmetry, a complete structure determination was not possible.
Bi2, das Bismuth-Homologe des Distickstoffs als Komplexligand in Bi2[W(CO)5]3 / Bi2, the Bismuth Homologue of Dinitrogen as a Ligand in Bi2[W(CO)5]3
Authors: Huttner Gottfried , Weber Ute , Zsolnai Laszlo
Published: February 2015

Reductive dehalogenation of BiCl3 with Na2W2(CO)10 leads to Bi2[W(CO)5]3 (1), which contains an axial Bi2 ligand side-on coordinated to three W(CO)5 groups. The star-type arrangement of three metal carbonyl moieties around a Bi2 axis with a very short Bi-Bi bond distance (281.8(3) pm) and a Bi2W3 core of approximate D3h symmetry is proved by an X-ray analysis (R1 = 0.041). 1 is thus the highest homologue of a series of complexes X2[W(CO)5]3 (X = As, Sb, Bi) and is the first stable molecular compound to contain a Bi2 ligand.
He(I) and He(II) Photoelectron Spectra of M[Co(CO)4]2 and M[Mn(CO)5]2 Complexes (M = Zn, Cd, and Hg)
Authors: Louwen Jaap N. , Andréa Ronald R. , Stufkens Derk J. , Oskam Ad
Published: February 2015

The He(I) and He(II) photoelectron spectra of M[Co(CO)4]2 and M[Mn(CO)5]2 complexes (M = Zn, Cd, Hg) are reported. Bands attributable to metal-metal bonds, metal d-levels and CO orbitals are assigned in agreement with a semi-ionic model, i.e. M2+ and [M'(CO)n]-. Relativistic effects prove to be important in assigning these ultraviolet photoelectron spectra.
ESR Studies on the Nitrosyl Complex of Hagfish (Myxine glutinosa L.) Hemoglobin
Authors: John Maliyakal E. , Lalthantluanga Ralte , Liljeqvist Gisela , Paléusa Sven , Braunitzer Gerhard
Published: February 2015

The nitric oxide complex of hagfish hemoglobin exhibits electron spin resonance spectra centered around g = 2 with rhombic symmetry. The six coordinated spectrum is not influenced by protonation or presence of inositol hexaphosphate. Thus, the critical substitutions at E 7 (His → Gln) and E 11 (Yal → Ile) do not disrupt the proximal histidineiron bonds in the nitrosyl complex of this primitive hemoglobin, though the same type of substitution are known to cause destabilization of R quaternary structure in tetrameric mammalian nitrosylhemoglobins. This difference could be related to the difference in tension existing in the respective hemes of tetrameric and monomeric hemoglobins.
Imine-Enamine Tautomerism -Nucleophilic Reactions of Imines
Authors: Rahman Atta-ur , Ahmad Viqar Uddin , Sultana Mumtaz , Perveen Nusrat , Sultana Nighat
Published: February 2015

A reinvestigation of the reactivity of N-isopropylidene cyclohexylamine to methyl acrylate by GC-MS analysis has shown that the major product is the β-aminoester (9) formed by the N-alkylation of cyclohexylamine which may be generated by a dimerisation-elimination sequence. A number of other products resulting from N-and C-alkylation of the ketimine have been identified.
Total Synthesis of PHI
Authors: Moroder L. , Göhring W. , Thamm P. , Wünsch E. , Tatemoto K. , Mutt V. , Bataille D.
Published: February 2015

PHI has recently been isolated from porcine duodenum as a new peptide factor with VIP-like activities. Its primary structure corresponds to a linear heptacosapeptide amide characterized by a remarkable sequence homology to the other known members of the glucagon family. The synthesis of this hormone candidate has been performed applying the strategy of overall acid-labile side-chain protection and the fragment condensation procedure. Upon assembly of the fragments to the fully protected heptacosapeptide amide, acidolytic deprotection with trifluoroacetic acid followed by purification of the resulting crude product via ion exchange chromatography and partition chromatography yielded synthetic PHI at a high degree of purity as judged from different analytical tests. Comparative analyses of the synthetic and natural product by means of chromatographic and biological assays confirmed the identity of the two PHI preparations.
Inversion der Calcium-Isotopenseparation an einem Ionenaustauscher durch Ver- änderung der LiCl-Elektrolytkonzentration / Inversion of the Calcium Isotope Separation at an Ion Exchanger Resin by Variation of the LiCl Electrolyte Concentration
Authors: Heumann Klaus G. , Klöppel H. , Sigl G.
Published: February 2015

The calcium isotope separation at a strongly acidic exchanger resin as a function of the concentration of a LiCl solution is investigated in column experiments. Whereas an enrichment of the heavier calcium isotopes in the solution phase is found with a 3 M LiCl solution, an inverse effect is obtained with 8 M and 12 M LiCl solutions. The separation effect e for the 12 M solution is found to be the highest calcium enrichment in a system without a complexing agent. The results are compared with those for other electrolyte solutions and can be explained by the anion/cation interactions.
13C NMR of the Tetrakis(phenylethynyl)borate Anion and of Some Phenylethynyl Boranes
Authors: Wrackmeyer Bernd
Published: February 2015

The 13C NMR parameters of the title compounds are assigned by heteronuclear triple resonance experiments 13C{1H,11B}. The magnitude of the coupling constants J(13C11B) corresponds roughly with J(13C13C). The chemical shifts δ13C reveal B-C(pp) π bonding which is, however, rather weak when compared with C+-C(pp) π bonding in phenylethynyl carbocations.
ESR Study on Complexes Formed on Reaction of cis-Dichlorodiammineplatinum(II) with Cytosine and Cytidine
Authors: Neubacher H. , Krieger J. , Zaplatynski P. , Lohmann W.
Published: February 2015

The ESR spectra of novel paramagnetic comple-xes between cis-dichlorodiammineplatinum(II) and cytosine or cytidine in aqueous solution are presented and discussed. The results imply a complex containing a binuclear metal-metal bonded platinum moiety with an unpaired electron spin delocalized over the dz2-orbitals.
A Total Synthesis of (±)-Vincamine and (±) -Eburnamonine
Authors: Rahman Atta-ur , Sultana Mumtaz
Published: February 2015

A synthesis of vincamine (1) and eburnamo-nine (2) is reported which involves a new route to the key intermediate (8).