bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthese, Eigenschaften und Struktur von Bipyridin-Halogeno-Komplexen des Cobalts / Synthesis, Properties and Structure of Bipyridine Halogeno Complexes of Cobalt
Authors: Krämer Thomas , Strähle Joachim
Published: March 2015

The cobalt(II) 2,2′-bipyridine complexes Co(2.2′bpy)2X2 (X = Cl, Br, I) have been synthesized from the anhydrous halides and a stoichiometric amount of 2,2′-bipyridinc in acetonitrile. From the IR spectra a trans configuration is assumed for the chloro complex. For the bromo and iodo compound an ionic form [Co(2,2′bpy)2X]X with a square pyramidal coordination of the Co atom is more likely. cis-[Co(2,2′bpy)2Cl2] · 1,5C2H4C12 was obtained from Co(2.2'bpy)2I2 in 1,2-dichloroethane. It crystallizes with Z = 4 in the monoclinic space group P21/n: a = 1379.4. b = 1325.9. c = 1423.9 pm. β = 97.11°. Very long Co−Cl bond distances of 239.2 and 245.0 pm are observed, while the Co−N distances (213.8 to 217.4 pm) are of normal length. Reaction of Co(2,2′bpy)2I2 with 4,4′-bipyridine yields [Co(2,2′bpy)2(4.4′bpy)]2+ which is easily oxidized to give a polymeric complex that exhibits a conductivity of 10-6 S/cm.
Ein neues Silicat-Anion: [Si(NCS)6]2- / A New Silicate Anion: [Si(NCS)6]2-
Authors: Heininger Wolfgang , Stucka Rolf , Nagorsen Günter
Published: March 2015

Crystalline salts of the new hexa-co-ordinated silicon complex anion [Si(NCS)6]2- were obtained by stoichiometric reaction of Si(NCS)4 with NEt4NCS. NMe4NCS or [DABCO · 2 Me](NCS)2 in acetonitrile. Their crystallographic data were determined:

[NEt4]2[Si(NCS)6]: tetragonal, P42/m, a = 1049 pm, c = 1546 pm, Z = 2.

[NMe4]2[Si(NCS)6]: rhombohedral, a = 879 pm, α = 83.2°, Z = 1.

[DABCO · 2 Me][Si(NCS)6]: triclinic, a = 933 pm, b = 1511 pm, c = 899 pm, α = 105.8°, β = 96.3°, γ = 103.5°, Z = 2.

The X-ray structure analysis of [NEt4]2[Si(NCS)6] shows silicon to be coordinated nearly octahedrally by the nitrogen atoms of two linear and four slightly bent NCS groups. The mean Si−N, N−C and C−S bond lengths are 182.1 pm. 115.2 pm and 160.3 pm, respectively.

IR spectra are reported. The positions of the [Si(NCS)6]2- bands are discussed in context with the structure.
Chrom(0)-und Molybdän(0)-Komplexe von 11-Isopropyliden-bicyclo[4.4.1]undeca-2,4,8-trienen / Chromium(0) and Molybdenum(0) Complexes of 11-Isopropylidene-bicyclo[4.4. 1]undeca-2,4,8-trienes
Authors: Kreiter Cornelius G. , Michels Eduard , Kaub Jürgen
Published: March 2015

11-Isopropylidene-bicyclo[4.4.1]undeca-2,4,8-triene (IBU, 1A) and five alkyl substituted de­rivatives (1B-1F) contain a conjugated diene unit and two isolated CC-double bonds, one exocyclic and one incorporated into the bicvclus, each suited for complexation to transition metals. With [Cr(CO)3(CH3CN)3] (2) 1A-1F form [Cr(CO)3(η6-IBU)] complexes (3A−3F). in which the IBU ligands are coordinated to the chromium via the diene unit and the exocyclic CC-double bond. The corresponding [Mo(CO)3(η6-IBU)] complexes (5A−5F) are obtained from the reactions of [Mo(CO)3(diglyme)] (4) with 1A−1F. In addition, the isomeric [Mo(CO)3(η6-IBU)] complexes (6A−6D) are formed, in which the IBU ligands are bound to molybdenum via the three cyclic CC-double bonds. The complexes 3A−3F, 5A−5F and 6A−6D were studied by IR and NMR spectroscopy (1H. 13C) and characterized by C, H elemental analyses. The crystal and molecular structure of 1A was determined by X-ray structure analysis.
Nitriles in Heterocyclic Synthesis: Novel Synthesis of 4H-Thiopyran and of 2-Hydroxy-6-pyridine Thione Derivatives / Galal Eldin Hamza Elgem eie, Sherif Mourad Sherif, Fatma Abd El Maksoud Abd El A al, and M ohamed Hilmy Elnagdi
Authors: Hamza Elgemeie Galal Eldin , Sherif Sherif Mourad , El Aal Fatma Abd El Maksoud Abd , Elnagdi Mohamed Hilmy
Published: March 2015

Reaction of arylmethylenemalononitrile 2a−c with cyanothioacetamide 1 afforded 4-aryl-2,6-diamino-4H-thiopyran-3,5-dicarbonitriles 5a−c on refluxing in ethanolic aqueous triethylamine, rearranged to yield the 4-aryl-1,2-dihydro-6-hydroxy-2-thioxo-3,5-pyridine dicarbonitriles 8a−c. The same compounds could be obtained on treatment of 2a−c with 1 in ethanolic aqueous triethylamine or on reacting 1 with 2d−f. The 13C NMR data of the products are reported and interpreted.
NOTIZEN: Beiträge zur Chemie der Schwefelhalogenide, 13 [1] Das Photoionisations-Massenspektrum von SBr2 / Contributions to the Chemistry of Sulfur Halogenides, 13 [1] The Photoionization Mass Spectrum of SBr2
Authors: Minkwitz R. , Lekies R. , Jochims H. W. , Freie Universität, Institut für Physikalische Chemie, Takust E. , Baumgärtel H.
Published: March 2015

The photoionization mass spectrum of SBr2 has been m easured and the (S−Br)-bond energy has been calculated from experimental data.
Zweikernige μ-Nitridokom plexe von Molybdän / Binuclear μ-Nitrido Complexes of Molybdenum
Authors: Schmitte Josef , Dehnicke Kurt
Published: March 2015

The μ-nitrido complexes [Mo2NC19]2⊖ and [Mo2NCl9]⊖, with PPh3Me⊕ as the counter ions, are prepared by reactions of [MoNC14]2⊖ and [MoNCl4]⊖, respectively, with molybdenum pentachloride in CH2Cl2. With POCl3 [Mo2NC19]2⊖ forms the donor-acceptor complex [Mo2NCl9(POCl3)]2⊖, whereas with acetonitrile disproportionation occurs, [MONCI4]⊖ and [MoCl5(CH3CN)]⊖ being formed, respectively. The IR spectra are discussed.
Zur Frage der nicht-enzymatischen Bildung von kondensierten Phosphaten unter präbiotischen Bedingungen/ Non-Enzymatic Formation of Condensed Phosphates under Prebiotic Conditions
Authors: Seel F. , Klos K.-P. , Recktenwald D. , Schuh J.
Published: March 2015

One of the problems of chemical evolution on the primitive Earth is the question of the possibility of a non-enzymatic spontaneous condensation o f phosphoric acid and hydrogen phosphates to yield polyphosphoric acids and polyphosphates in aqueous system s, by means of which phosphorus might have entered into early metabolisms. The extra- or intra-cellular formation of magnesium diphosphate under geologically plausible hydrothermal conditions from either magnesium hydrogen phosphates or calcium phosphates in media has been demonstrated.
Synthese und Kristallstruktur von VBr2(N3S2)(Pyridin)2/ Synthesis and Crystal Structure of VBr2(N3S2)(pyridine)2
Authors: Willing Wolfgang , Christophersen Ruth , Müller Ulrich , Dehnicke Kurt
Published: March 2015

VBr2(N3S2)(pyridine)2 is obtained in form of brown-black, moisture sensitive crystals by the reaction of the corresponding chloro complex with trim ethylbrom osilane. The com pound is characterized by its IR spectrum and an X-ray crystal structure determination (1322 observed reflexions, R = 0.077). Crystal data: monoclinic, space group Aba2, Z = 4, a = 1100.3, b = 1480.0, c = 983.3 pm.

A molecular structure with a distorted octahedral coordination for the vanadium atoms was found: there are two short VN bonds o f 178 pm with two N atoms o f the planar N3S2 chelate, two long (228 pm) VN(pyridine) bonds trans to the former VN bonds and two bromo ligands.
1,1,3,5,5,7,9,9,11-Nonachlor-1,5,9-triphospha-2,4,6,8,10,12-hexaazacyclododecahexaen: [Cl2PN2CCl]3, Synthese, Spektren und Kristallstruktur/ 1,1,3,5,5,7,9,9,11-Nonachloro-1,5,9-triphospha-2,4,6,8,10,12-hexaazacyclododecahexaene: [Cl2PN2CCl]3, Preparation, Spectra and Crystal Structure
Authors: Hausen H .-D. , Rajca G. , Weidlein J.
Published: March 2015

The title compound, Cl2PN2CCl, has been synthesized by the reaction of PCl5 with Me3Si -N = C = N - SiMe3 (Me - CH3) in a 1:1 molar ratio. The colourless com pound is trimericin benzene solution and in the solid state and has a structure with a highly puckered 12-membered P3N6C3-ring skeleton of low symmetry. The X-ray structure determination shows a monoclinic space group P 21/a with 4 trimeric units per cell.
Übergangsmetallkomplexe mit Schwefelliganden, XVIII. Synthese und Reaktionen von [Ru(L)(PPh3)dttd]-Komplexen mit kleinen Stickstoffverbindungen L = NH3, N2H4, N2H3CH3, N2H3C6H5 sowie NO+ (dttd2- = 2,3;8,9-Dibenzo-1,4,7,10-tetrathiadecan (–2))/ Transition Metal Complexes with Sulfur Ligands, XVIII. Synthesis and Reactions of [Ru(L)(PPh3)dttd] Complexes with Small Nitrogen Compounds L = NH3, N2H4, N2H3CH3, N2H3C6H5 and NO+ (dttd2- = 2,3;8,9-Dibenzo-1,4,7,10-tetrathiadecane (–2))
Authors: Sellmann Dieter , Waeber Michael
Published: March 2015

Reaktionen von [Ru(L)(PPh3)dttd]-Komplexen mit kleinen Stickstoffverbindungen L = NH3, N2H4, N2H3CH3, N2H3C6H5 sowie NO+ (dttd2-= 2,3;8,9-Dibenzo-l,4,7,10-tetrathiadecan (—2)) Transition Metal Complexes with Sulfur Ligands, XVIII* Synthesis and Reactions of [R u(L)(PPh3)dttd] Complexes with Small Nitrogen Com pounds L = N H 3, N2H 4, N2H 3C H 3, N2H 3C6H 5 and N O + (dttd2-= 2,3;8,9-D ibenzo-l,4,7,10-tetrathiadecane (—2)) D ieter Sellmann+ Ruthenium Sulfur C om plexes, N itrogen Ligands The com plex fragment [Ru(PPh3)dttd], (dttd2-= 2,3;8,9-dibenzo-l,4,7,10-tetrath iad ecane (— 2)), coordinates small nitrogen com pounds, which have only o-as well as a-jr-donor proper­ ties. The reactions o f [Ru(PPh3)2dttd] with L — N H 3, N 2H 4, N 2H 3C H 3 and N 2H 3C6H 5, respec­ tively, give the corresponding [R u(L)(PP h3)dttd] com plexes. O xidation o f the hydrazine com ­ plex [R u(N 2H 4)(PPh3)dttd] yields [a-N 2H 2{R u(PP h3)dttd }2], the first diazene com plex in which the unstable N 2H 2 is bound to a sulfur coordinated m etal center and stabilized by a 4 c —6 e Ru— N — N — Ru system , steric shielding as well as thiolate — S---H (n,h2)---N hydrogen bridges. The reactions of the ammonia and the hydrazine com plexes, respectively, with N O PF6 yield the nitrosyl com plex [R u (N O)(PP h3)dttd]PF6 as final product; in the case o f [R u(N 2H 4)(P P h3)dttd] the intermediate formation of an azido com plex is observed IR -spectroscopically.
Darstellung, Kristallstruktur und Schwingungsspektren von cyclo-Undekaschwefel (S11) und von cyclo-Tridekaschwefel (S13) / Preparation, Crystal Structure, and Vibrational Spectra of cyclo-Undecasulfur (S11) and of cyclo-Tridecasulfur (S13)
Authors: Steudel Ralf , Steidel Jürgen , Sandow Torsten
Published: March 2015

The homocyclic S11 and S13 molecules have been synthesized from titanocenepentasulfide and S6Cl2 or S8Cl2, respectively, and obtained as yellow crystals which are metastable for several days at 20 °C. X-Ray structural analyses of single crystals at -105± 5 °C exhibited molecules of approximately C2 symmetry with bond distances (d), bond angles (a) and torsional angles (r) in the following ranges: S11 : d = 203.2 -211.0 pm, α = 103.3-108.6°, τ = 69.3 - 140.5°; S13: d = 197.8 - 211.3 pm, α = 102.8-111.1°, τ = 29.5 - 116.3°. Infrared and Raman spectra of S11 and S13 are reported. In addition, the synthesis of S6Cl2 and S8Cl2 from S6 or S8, respectively, and chlorine is described.
Dialkylchalkogenidverbrückte Carbonylzweikernkomplexe des Typs [M]2ER2 mit M = {CpMn(CO)2} und {Cr(CO)5}; E = S, Se, Te; R = Me oder R2 = (CH2)3 bzw. (CH2)4; Röntgenstrukturanalyse von [CpMn(CO)2]2S(CH2)3 / Dialkylchalcogenide-Bridged Dinuclear Carbonyl Complexes of the Type [M]2ER2 with M = {CpMn(CO)2} and {Cr(CO)5}; E = S, Se, Te; R = Me or R2 = (CH2)3, (CH2)4; X-Ray-Structure Analysis of [CpMn(CO)2]2S(CH2)3
Authors: Bremer Gerhard , Boese Roland , Keddo Mustafa , Kruck Thomas
Published: March 2015

The reaction of CpMn(CO)2THF or Cr(CO)5THF with alkylchalcogenides ER2 (E = S, Se, Te; R = Me or R2 = (CH2)3, (CH2)4) in the molar ratio of 2:1 gives alkylchalcogenide-bridged dinuclear complexes [CpMn(CO)2]2ER2 and [Cr(CO)5]2ER2. The heteronuclear complex Cp(CO)2Mn - (μ-SMe2) -Cr(CO)5 can be synthesized by reacting CpMn(CO)2SMe2 with Cr(CO)5THF. X-ray structure analysis of the compound [CpMn(CO)2]2S(CH2)3 demonstrates the bridging character of the alkylchalcogenides.
Die Kristallstruktur des Bis(tetrapropylammonium)heptasulfids [N(C3H7)4]2S7 / The Crystal Structure of Bis(tetrapropylammonium)heptasulfide [N(C3H7)4]2S7
Authors: Böttcher P. , Flamm W.
Published: March 2015

Bis(tetrapropylammonium)heptasulfide results from the reaction of [(C3H7)4N]Br and Na2S5 (molar ratio 4:1 to 2:1) in aqueous solution. The dark orange compound crystallizes in the space group P21/c, the lattice constants are (at -70 °C): a = 9.466(4) Å , b = 11.013(3) Å, c = 16.845(7) Å , β = 105.6(1)°. It contains unbranched chainlike S7
2− anions of all-trans-conformation.
Metallkomplexe funktioneller Isocyanide, XIII Bis(oxazolidin-2-yliden)-Komplexe von Mangan(I) und Nickel(II) / Metal Complexes of Functional Isocyanides, XIII Bis(oxazolidin-2-ylidene) Complexes of Manganese(I) and Nickel(II)
Authors: Fehlhammer Wolf Peter , Plaia Ulrike
Published: March 2015

The dicarbene complexes, MnBr(CO)3 [xxx] (1) and [xxx] (2), are synthesized from metal carbonyl precursors and CNCH2CH2OH . Factors influencing this 2-hydroxyalkyl isocyanide → N ,O-carbene isomerization are discussed. The crystal and molecular structure of 2 shows a distorted trigonal geometry about the central Ni atom. Extensive hydrogen bonding ((N )H ··· F 2.09, 2.38 Å ) occurs between cations and anions giving rise to infinite chains. Other pertinent bonding parameters are Ni-C (carbene) 1.860(4), 1.864(4) Å; C(carbene) [xxx] N 1.309(6), 1.304(6) Å , and C - Ni - C 97.7(2)°.
Große Übergangsmetallcluster, IV Ru55-, Rh55- und Pt55-Cluster / Large Transition Metal Clusters, IV Ru55-, Rh55- and Pt55-Clusters
Authors: Schmid Günter , Huster Wilfried
Published: March 2015

The novel cluster compounds Ru55[P (tert -Bu)3]12Cl20, Rh55(PPh3)12Cl6 and Pt55[As(tert -Bu)3]12Cl20 have been prepared by the reaction of (RuCl3/P (tert-Bu)3), (Ph3P)3RhCl and trans-[As(tert -Bu)3]2PtCl2, respectively, with B2H6 in THF or benzene. Diborane reduces the metal salts and serves to capture excess of phosphine or arsine ligands. Molecular weight determinations prove the cluster size. High resolution transmission electron microscopic investigations on the Pt55 cluster show the expected full-shell cuboctahedron with 55 closest-packed platinum atoms. 31P NMR spectra prove the ligands to be very mobile.
Uber die drei discotischen Mesophasen der scyllo-Inosithexaester / On the Three Discotic Mesophases of scyllo-Inositol Hexaesters
Authors: Kohne Bernd , Praefcke Klaus , Billard Jan
Published: March 2015

The mesophases of eleven homologous hexaesters ( 1b -1) of the naturally occurring scylloinositol (1a ) representing the first series of alicyclic saturated discogens are studied by calorimetry and optical microscopy. The three derivatives 1 b -d of this hexahydroxy cyclohexane with each six acetyl, propionyl or butyroyl side chains, respectively, exhibit a very organized discophase D1. The hexa-0-acetyl-scyllo-inositol (1b , range of mesophase: Δt = 4.8 °C!) is the discogen having the shortest identical ester groups as lateral functions so far reported for discotic liquid crystals. The pentanoyloxy com pound (1e) exhibits a monotopic D0 mesophase and an enantiotropic optically isotropic and, probably, cubic mesophase D0 different from the smectic D mesophase.

Versus increasing temperature the phase sequences are D1 → DE and D1 → D0. Examples of mutual orientation of D1 and DE discophases and binary mixtures exhibiting stable DE discophase at room temperature are also reported. The mesophases of seven more compounds (1f-1) of the homologous series having lateral functions larger than pentanoyloxy are identified by total miscibility as discophase DE. Their stable temperature ranges are very wide e.g. hexa-0-heptanoyl-scyllo- inositol (1g , Δt = 132 °C) which are exceeded only by those discogens having much larger “cores” (up to now of aromatic character only).
Untersuchungen zur möglichen Existenz des S4N4
⊕-Radikalkations und die Kristallstruktur von S4N4[FeCl4] / Investigations Concerning the Possible Existence of the S4N4
⊕ Radical Cation and the Crystal Structure of S4N4H[FeCl4]
Authors: Thewalt Ulf , Holl Konrad , Demant Udo , Müller Ulrich , Dehnicke Kurt
Published: March 2015

Brom ination o f S4N 4 Cl[FeCl4], Preparation o f S4N 4 H [FeX 4] (X = Cl, Br), IR Spectra, Crystal Structure of S4N4H[FeCI4] S4N 4 H [FeC l4] as well as S4N 4 D [F eC l4] were prepared in C H 2C12 by reaction o f S4N 4 with FeC l3 and C H 3C O O H and CH 3C O O D , respectively. Bromination o f S4N 4C l[FeCl4] with M e3SiBr in C H 2 C12 yields S4N 4 H[FeBr4]; in this reaction, S4N 4 Br® is presumably formed initially; it then decom p oses by elimination o f bromine and formation of the S4N 4® radical cation; the latter reacts with the solvent, yielding the S4N 4 H® cation. Brom ination of S3N 2C l[FeCl4] with M e3SiBr affords S6N 4 [FeBr4]2. The IR spectra o f the com pounds are discussed. The crystal structure o f S4N 4 H [FeC l4] was determined by X-ray diffraction (1210 observed reflexions, R = 0.035). Crystal data: a = 803.8, b — 1003.9, c = 1507.7 pm, β = 104.52°, Z = 4, space group P 2,/c.
Characterisation of Metal Binding Sites for 8-Azaguanine and 8-Azahypoxanthine Derivatives Synthesis and X-Ray Structural Analysis of Methylmercury(II) and Zinc(II) Complexes
Authors: Sheldrick W. S. , Bell P.
Published: March 2015

The complexes [(CH3Hg)AGuaH ] (1) and [(CH3Hg)2AGua] • H2O (2) have been isolated from aqueous 1:1 and 2:1 solutions of CH3HgOH and 8 -azaguanine (AGuaH2) at respective pH values of 5 and 9. Only one CH3Hg+ complex of 8 -azahypoxanthine (AHxH2), namely [(CH3Hg)2AHx] (3), could be isolated under analogous conditions. X-ray structural analyses established N1 and N9 as metal binding sites in 3 and N9 as the coordination position in [Zn(H2O)4(AHxH)2] (4). With 8-aza-9-benzylhypoxanthine (9-BzAHxH) only one CH3Hg+ complex [(CH3Hg)9-BzAHx] (5) could be isolated in the pH range 2-10. N1 was established by X-ray structural analysis as the binding site. The relevance o f these findings to an understanding of ligand behaviour of the antineoplastic agent 8 -azaguanine is discussed.
Reaktionen von Tetrapropyldibismutan mit Chalkogenen und Tetramethyldistiban / Reactions of Tetrapropyldibism uthane with Chalcogens and Tetramethyldistibane
Authors: Breunig Hans Joachim , Müller Ditmar
Published: March 2015

Bis(dipropylbismuth)oxide, -sulfide, -selenide and -telluride are obtained by reactions of tetra­ propyldibismuthane with elem entaloxygen, sulfur, selenium or tellurium. Tetramethyldistibane and tetrapropyldibismuthane undergo an exchange reaction to give (dipropylbismuthino)-dimethylstibane.
Discarin-I, ein neues Peptidalkaloid aus Discaria febrifuga Martius / Discarine-I, a New Peptide Alkaloid from Discaria febrifuga Martius
Authors: Hennig Peter , Morel Ademir , Voelter Wolfgang
Published: March 2015

Besides the already reported alkaloids [1-5] from the root bark extract of Discaria febrifuga Martius, two further peptide alkaloids, the known discarine-B and discarine-I are isolated and their structures elucidated. Discarine-I is a fourteen-m em bered ring peptide alkaloid and the ring is constituted by p-hydroxy styrylamine, β-hydroxyleucine, N-methylisoleucine and tryptophan
Reaktionen N-silylierter Endiamine, I Übergangsmetallkomplexe von 1,3-Diaza-2-sila-4-cyclopentenen / Reactions of N-Silated Endiamines, I Transition Metal Complexes of 1,3-Diaza-2-sila-4-cyclopentenes
Authors: Zettlitzer Michael , Dieck Heindirk tom , Stamp Lutz
Published: March 2015

1,3-Di̲aza-2-s̱ila-4-c̱yclopentenes 1 (DISC), which are electron-rich and easily oxidizable ole­ fins, form strongly coloured, but poorly soluble 1:1 adducts with cuprous halides, while silver trifluoromethylsulfonate oxidizes 1. Much more soluble and again strongly coloured complexes of stoichiometry LPdX2, (L)1.5PdX2 and L 2PdX2 are formed from 1 and palladium halides. The well-crystallizing adduct (PdCl2 · L)2 3a was chosen for an X-ray structure analysis (monoclinic, space group P2/c; a = 10.215(3), b = 14.681(3), c =23.642(5) Å , β = 101.31(2)°; Z = 8 ; R = 0.054), which revealed an almost planar DISC ligand in an oblique η2(C=C)-coordination relative to the π-plane. Structural data and rather peculiar spectroscopic properties encourage a comparison of 3a with complexes, in which an electron-rich olefin is split to give a bis(carbene) ligand system. The electronic reasons for the splitting of electron-rich olefins at d8 metals are discussed under symmetry considerations.
Alternativ-Liganden X X Neue Komplexe M(CO)3L mit Tripodliganden MeGe(OCH2PMe2)3 und MeSi(OCH2PMe2)x(CH2CH2PMe2)3-x (M = Cr, Mo, W; x: = 0-2) / Alternative Ligands X X Novel Complexes M(CO)3L with Tripod Ligands MeGe(OCH2PMe2)3 and MeSi(OCH2PMe2)x(CH2CH2PMe2)3-x (M = Cr, Mo, W; x: = 0-2)
Authors: Grobe Joseph , Krummen Norbert
Published: March 2015

Tripod ligands MeGe(OCH2PMe2)3 (1) and MeSi(OCH2PMe2)x(CH2CH2PMe2)3-x (x = 0-2) (4-6) have been prepared by reacting MeGeCK and MeSiClxVi3-x (x = 1. 2). respectively, with Me2PCH2OH in the presence of a tertiary amine (NEt3 or NMe3), in case of the resulting vinylsilane derivatives MeSi(OCH2PMe2)xVi3-x (x = 2: 2; x = 1: 3) and MeSiVi3 followed by the photochemical addition of Me2PH to the vinyl groups. Replacement of the cycloheptatriene ligand in M(CO)3CHT compounds (M = Cr. Mo, W) yields the new complexes fac-M(CO)3[MeGe(OCH2PMe2)3] (7-9) and fac-M(CO)3[MeSi(OCH2PMe2)x(CH2CH2PMe2)3-x] (10-18). The ligand properties of 1 and 4-6 have been studied by determining the effects of coordination on the spectroscopic data (νco, 1H, 31P NMR).
Metallkomplexe mit biologisch wichtigen Liganden, XLII [1]. Carbonylmetallkomplexe mit Anionen von mehrfunktionellen α-Aminosäuren / Metal Complexes with Biologically Important Ligands, XLII [1].Carbonyl Metal Complexes with Anions of Polyfunctional α-Amino Acids
Authors: Meder Hans-Jochen , Beck Wolfgang
Published: March 2015

A series of carbonyl metal complexes with anions of functional α-amino acids has been pre­pared: [M(CO)3(L-histidinate)]- (M = Cr. Mo, W), M(CO)3(L-histidinate) (M = Mn, Re), [Re(CO)3(NO)(L-histidinate)]+ PF6
-,M(CO)2(η3-allyl)(L-histidinate) (M = Mo, W), Mo(CO)2(NO)(L-histidinate), [Mo(CO)(NO)(η3-methallyl)(L-histidinate)]PF6, Mo(CO)2(η3-methallyl)(L-histidineOMe)Cl, [M(CO)3,(cysteinate)]2- (M = Mo. W), [Mo(CO)3(glyglyO)(H2O)]- , [Re(CO)3(L-ornithinate)(CH3CN)] and [Re(CO)3(L-lysinate)]. The IR and NMR data of the new complexes are reported.
Formation of Triradical Trications from Hexaquaternary Salts Derived from 4,4'-Bipyridine
Authors: McGeachie Joanne , Summers Lindsay A .
Published: March 2015

The syntheses of the hexaquaternary salts 1,1'-bis-[2-(1′-methyl-[4,4'-bipyridinium]-1-yl)-ethyl]-4,4'-bipyridinium hexaperchlorate and 1,1'-bis-[3-(1'-methyl-[4,4'-bipyridinium]-1-yl)-propyl]-4,4'-bipyridinium hexaperchlorate are reported. The salts are reduced in aqueous solution to triradical trications at a potential (E0) of -0.24 V.
meso-Substituierte Porphyrine, 4 [1] / meso-Substituted Porphyrins, 4 [1]
Authors: Volz Heinrich , Hassler Michael , Schäffer Hermann
Published: March 2015

2-Pyrryl-(3.5-dimethylphenyI)-carbinol, 2-pyrryl-(3,5-di-t-butyl-phenyl)-carbinol and 2-pyrryl- mcsityl-carbinol are cyclised in acidic medium to the corresponding meso-tetraarylporphyrins. The meso-tetraarylporphyrins are transfered to the iron complexes. The reactions of the iron- porphyrins with OH⊖ and H3CO⊖ are studied and the products of these reactions are character­ised.
Ring-Ketten-Isomerie substituierter Tetrahydropyridinderivate / Ring Chain Isomerism of Substituted Tetrahydropyridines
Authors: Möhrle Hans , Dwuletzki Heinz
Published: March 2015

The reactions of δ-bromoketones 1 with amines lead to cyclic enamines 6 or secondary δ-am inoketones 3 depending on the nature of the amine used. Amino substituents which increase the nucleophilicity forces the course of the reaction towards cyclisation to 6 , which in turn yields the corresponding iminium salts 5. This pathway can be suppressed by large substituents leading to the formation of ammonium salts 4.
Synthesis and Crystal Structure of CuC4O4·2 H2O
Authors: Robl Christian , Weiss Armin
Published: March 2015

The monoclinic compound CuC4O4·2 H2O (space group P 21/c) was prepared from aqueous acetate buffered solution. The structure was solved from a twinned crystal. Chains consisting of squarate dianions and Cu2+ , which is coordinated octahedrally in a strongly distorted manner, are the main feature. Only two squarate oxygen atoms contribute considerably to the coordination of Cu2+. Neighbouring chains share common oxygen atoms (H2O . Osquarate) of the coordination polyhedra. Furthermore the chains are very probably interlinked by strong hydrogen bonds. Thermal decomposition of CuC4O4·2 H2O leads to CuO.
A TTF Derivative Acting as a Chelate Ligand: Structure of μ-[Tetra(methylthio)tetrathiafulvalene]di[diodoniercury(II)], (TTM-TTF) (HgI2)2, and the Structure of a Second Modification of Free TTM-TTF
Authors: Endres Helmut
Published: March 2015

(TTM -TTF)(HgI2)2 [TTM -TTF = tetra(methylthio)tetrathiafulvalene, C10H12S8] was obtained as one of the products of the reaction of TTM -TTF with HgI2 . It is triclinic, P 1̄ , a = 7.667(1), b = 8.308(2), c = 11.608(3) Å , α = 81.42(2), β = 75.15(2), γ = 67.06(2)°, V = 657.2 Å3, Z = 1, Mr = 1297.53, dc = 3.28 g cm-3, final RK = 0.035 for 2755 reflections and 116 parameters. The donor acts as a bridging chelate ligand by coordination of the S atoms of the -SCH , groups to Hg, with Hg -S distances of 3.038(2) and 3.157(3) Å . Hg···I contacts of 3.648(1) and 3.761(1) Å lead to coordination-polymer like chains of the Hg complexes. TTM -TTF (phase II) is triclinic, P 1̄, a = 5.141(2). b = 7.565(3), c = 10.950(2) Å , α = 72.46(2), β = 79.03(2), γ = 84.87(3)°, V = 398.4 Å3, Z = 1, Mr = 388.73, dc = 1.62 g cm-3, final Rw = 0.032 for 1876 reflections and 106 parameters. The molecules form sheets of stacks with shorter interstack S···S contacts [3.591(1) Å] than within the same stack [3.720(1) Å].
Synthese und Kristallstruktur von Bis[1,5-ditolylpentaazadienido-thallium(I)] und Bis[1,3-diphenyltriazenido-thallium(I)]/Synthesis and Crystal Structure of Bis[1,5-Ditolylpentaazadienido-thallium(I)] and Bis[ 1,3-diphenyltriazenido-thallium(I)]
Authors: Beck Johannes , Strähle Joachim
Published: March 2015

The reaction of TlNO3 with 1,5-ditolylpentaazadiene in aqueous ammonia yields red [Tl(TolNNNNNTol)]2, which crystallizes in the monoclinic space group C2/c with the lattice constants a = 3322.9, b = 847.6, c = 1107.9 pm, β = 105.93°, Z = 4. The structure consists of dimeric molecules, in which two separate pentaazadienido chains and two T1 atom s are so arranged as to form trigonal pyramids, TlN3, with an average Tl-N distance of 274 pm. The N -N distances in the N5 chain are equal within the standard deviations, indicating a high ionic character for the Tl -N bonds. Intermolecular interactions link the dimers into infinite chains. Each Tl atom , already coordinated by three nitrogen atoms, is additionally coordinated by two nitrogen atoms of one neighbouring complex and the aromatic tolyl ring of another ligand. The distance between Tl and the π-bonded tolyl ring is 333 pm, comparable with values of other Tl arene complexes.

The reaction of TlNO3 with 1,3-diphenyltriazene in the presence of NaOH yields red [Tl(PhNNNPh)]2, which crystallizes in the monoclinic space group P21/n with the lattice constants a = 1040.6, b = 636.7, c = 1763.5 pm, β = 96.98°, Z = 2. The structure consists of centrosymmetric dimeric molecules. The 1,3-diphenyltriazenide anion acts as an unsymmetrical bidentate chelating ligand for each Tl atom. The Tl-N distances (Tl-N1 = 261, Tl -N3 = 277 pm) are significantly different. N1 is additionally bonded to the Tl atom of the neighbouring monomer. The dimeric complexes form a planar, four-membered Tl2N2 ring in the form of a slightly distorted square. π-Interactions between Tl and a phenyl ring of a neighbouring complex link the dimers to form infinite chains with a Tl-phenyl distance of 327 pm.
Bonding in the BaPdSn3 Structure
Authors: Li Jing , Hoffmann Roald
Published: March 2015

The body-centered BaPdSn3 structure contains Sn atoms in tetrahedral and square-pyramidal five-coordinate sites, and Pd in square-pyramidal environm ents. The PdSn3
2- three-dimensional lattice can be formally decomposed into first two-dimensional layers, then into a square Sn lattice with capping Sn and Pd atoms. This geometrical decomposition also serves as a construction principle for building up the electronic structure of this material. Many similarities to BaAl4 emerge. There is electron deficient multicenter bonding in the layer, normal two-center bonding Sn-Pd between layers. Pd 4d orbitals do not contribute significantly to the bonding.
Molecular Complexes, 8 Formation Constants and Topology of Complexes of Tetramethyluric Acid. An 1H NMR Reinvestigation Based on the AUS Concept and on the Shift Difference Method. A Revised Complex Topology
Authors: Jäckel Hannelore , Stamm Helmut
Published: March 2015

The complexation of tetramethyluric acid (TMU) with the donors (D) benzene (B), biphenyl (BP), naphthalene (N), and phenanthrene (P) in CCl4 is investigated by 1H NMR shift measure­ments relative to an external reference in a series of solutions containing a constant concentration of TMU and varying concentrations of D under conditions of a great excess of D. Reduction of data according to the AUS concept (additional nonspecific shielding) provided formation con­stants K (in 1/mol) and Icpt/K as approximations of the complex shifts. The increase in K from .17 (TMU-B) to .75 (TMU-N) to 2.08 (TMU -P) is compatible with a face-to-face complexation and with a preferred contact between the donor and TMU along the area of positive charge in the TMU molecule. The estimated Icpt/K figures indicate the centers of the complexes to lie between N-3 and N-9 of TMU, quite in the center of the positive charge area of TMU. K and Icpt/K figures for TMU-BP indicate this complex to have the same topology as TMU-B. the second ring of BP rotating in plane around the complexing ring of BP. The previous rejection of a face-to-face topology for such complexes was based on a misinterpretation of the ring current calculations. Deviating complex parameters in the previous report are shown to be caused by a solvent effect (CDCl3) and in part by methodical errors.
Differences between the Reaction of 2-Benzylidenecyclopentanone with Malononitrile and the Reaction of Cyclopentylidenemalononitrile with Aromatic Aldehydes; Synthesis of Strong Fluorescent o-Aminonitriles
Authors: Mirek Julian , Milart Piotr
Published: March 2015

It was found that instead of the Knoevenagel condensation of cyclopentylidenemalononitrile with aromatic aldehydes, a complex reaction takes place leading to 5,7-dicyano-1-arylidene-4-arylindanes. The same compounds were formed in the reaction of the cyclopentylidenemalono­nitrile dimer with aldehydes. It is suggested that the cyclopentylidenem alononitrile dimers un­dergo an electrocyclic ring opening leading to conjugated triene systems. These species are very reactive intermediates and may react with aldehydes in the next step. Bulky substituents in 2,5-dibenzylidenecyclopentanone hindered its Knoevenagel condensation with malononitrile but did not hinder its Michael addition leading to a 4H -pyrane derivative. Solutions of the obtained o-aminonitriles exhibit strong fluorescence in a variety of solvents.
The Crystal Structure of TeCl3
+ AuCl4
-
Authors: Jones Peter G. , Jentsch Dieter , Schwarzmann Einhard
Published: March 2015

TeCl3
+ AuO4
- crystallizes in the triclinic space group P1̄ with a = 7.564(2), b = 7.720(3), c = 8.964(3) Å , α = 78.26(3), β = 88.84(3), γ = 89.35(3)°, Z = 2. The structure was refined to R 0.041 for 1380 reflections. The cation polyhedron, including secondary Te···Cl interactions, is a square pyramid with mean Te -Cl 2.294, Te···Cl 3.028 Å. The secondary interactions link the ions to form centrosymmetric (TeCl3·AuCl4)2 dimers.
Polymerie 2,5-Dihydroxy-1,4-benzoquinone Transition Metal Complexes Na2(H2O)24[M2(C6H2O4)3] (M = Mn2+, Cd2+)
Authors: Weiss Armin , Riegler Eugen , Robl Christian
Published: March 2015

The isotypic compounds Na2(H2O)24[M2(C6H2O4)3] (M = Mn2+, Cd2+) form infinite net-like layers. The transition metal ion is coordinated octahedrally. The dianion of 2,5-dihydroxy-1.4- benzoquinone, consisting of two allyl systems interlinked by two long C-C distances (152-153 pm), acts as a chelating ligand. Adjacent layers are connected by hydrogen bonds. The stacking sequence of these layers, ···AAA···, leads to channels, which are filled by hydrated Na+ ions. The Na+ ions are coordinated in a distorted octahedral fashion, with neighbouring octahedra sharing common faces.
On the Autoxidation of Aqueous Sodium Polysulfide [1]
Authors: Steudel Ralf , Holdt Gabriele , Nagorka Regine
Published: March 2015

Aqueous sodium polysulfide of composition in the range Na2S2.0 to Na2S4.6 undergoes autoxidation by either air or pure oxygen at temperatures of between 23 and 40 °C according to the equation

[xxx]

Iodometric determination, vibrational spectra and ion-pair chromatography showed that neither sulfate, sulfite nor polythionates are formed and that the sulfur precipitated consists of S8 (≥ 99%).
Partition Coefficients of Biologically Important Pyrimidines and Purines [1]
Authors: Párkányi Cyril , Shieh Dah-Chung
Published: March 2015

Partition coefficients of sixteen biologically important pyrimidines and purines between an organic phase and water have been determined and the best organic solvents for their extraction have been suggested.
Elektronenreiche Olefine, 3 / Electron Rich Olefins, 3
Authors: Bessenbacher Christian , Kaim Wolfgang
Published: March 2015

Exhaustive reductive silylation of 2-trimethylsilyl-1,2,3-triazole (1) using Me,SiCl/K yields the new E-1,1,4,4-tetrakis(trimethylsilyl)-l,4-diazabutene(2) (4) as final product together with N(SiMe3)3. Initial reductive 1,4-addition to 1 leads to formation of 1.2.3-tris(trimethylsilyl)-1,2,3-triazoline(4) (2) as an intermediate which is rapidly reduced and silylated further to give the butene 4. Partial π overlap within the five-membered ring 2 containing 8 π electrons and three neighbouring unshared electron pairs is evident from NMR shifts and electron transfer reaction with TCNE. Photoelectron spectroscopy of 4 and the lability of its radical cation 4+. as studied by ESR show that this system cannot adopt a planar conformation in contrast to the tetrazene(2) analogue.
Influence of Decreasing Solvent Polarity (Dioxane-Water Mixtures) on the Stability of Metal Ion Complexes Formed with Phosphate Monoesters
Authors: Liang Guogang , Corfù Nicolas A. , Sigel Helmut
Published: March 2015

The acidity constants of H(R-MP)-, where R-MP2- = 4-nitrophenyl phosphate (NPhP2-), phenyl phosphate (PhP2-) and D-ribose 5′-monophosphate (RibMP2-), and the stability constants of the binary Cu(R-MP) complexes were determined by potentiometric pH titrations in aqueous solution and in 20, 30, 40 and 50% (v/v) dioxane-water mixtures. The solvent influence on the corresponding equilibrium constants is compared with the same influence on previously studied systems containing uridine 5′-triphosphate, formate or acetate. The influence of the solvent composition on the various ligand (L) systems was evaluated by constructing log KM(L) versus pKH(L)
H plots; in all cases straight lines are obtained with slopes close to 1. This indicates that in all these systems, despite the different negative charges of the involved ligands, the solvent effect on proton binding and on metal ion binding is approximately of the same size: A decreasing solvent polarity resulting from the addition of increasing amounts of organic solvent to the aqueous solutions favors the affinity of the negatively charged ligands for protons and metal ions as well. Information of this type is considered important because the ‘effective’ or ‘equivalent solution’ dielectric constants in active-site cavities of enzymes are reduced compared with the dielectric constant of bulk water; i. e., in protein cavities also a decreased ‘solvent polarity’ is occurring and this is expected to affect the stability of metal ion-ligand bonds.
Synthese und Struktur von α,β-ungesättigten aliphatischen Diazenen / Preparation and Structures of α,β-Unsaturated Aliphatic Diazenes
Authors: Roesky Herbert W. , Otten Uwe , Herbst Regine , Noltemeyer Mathias
Published: March 2015

The reactions of 1,1,2,2-tetrafluoroethane-1,2-bisulfenyl-chloride 1 and symmetrical azines 2 yield the conjugated trans-diazenes 3 as deep-coloured solids. Unsymmetrical azines 4 react with 1 under elimination of hydrogen chloride to give 1,3-dithiolane-substituted azine derivatives as pale-coloured liquids. The crystal structure of 3b has been determined by single crystal X-ray diffraction. A participation of the phenyl group in the conjugated system is not observed in 3b.
Metallorganische Verbindungen für MOCVD-Prozesse: Kristallstruktur des dimeren Addukts [Et3AsXAsCl3]2 / Crystal Structure of the Dimeric Triethylarsine-Arsenictrichloride Adduct, Dimer [Et3AsxAsCl3: Synthesis, Molecular and Crystal Structure
Authors: Baum Gerhard , Greiling Arnd , Massa Werner , Hui Benjamin C. , Lorberth Jörg
Published: March 2015

Reaction of Et3As with AsCl3 in n-pentane yields dimeric [Et3AsxAsCl3]2 in quantitative yield; sublimation in vacuo affords white crystals.

X-Ray diffraction data were collected at 133 K (3149 independent observed reflections; R = 0.029. Rw = 0.026). Crystal data: monoclinic space group P21/c, a = 761.9(8). b = 1118.8(4). c = 1406.0(14) pm; β = 100.90(4)°. Ζ = 2 dimers.

The dimer contains a planar As2Cl6-unit with terminal and bridging As-Cl bonds; each arsenic atom is bonded to a Et3As molecule via an arsenic-arsenic bond. The dimer thus has pseudo four- and six-coordinate arsenic atoms.
Solid State Structure of 2,2,4,4,6,6-Hexa(β-naphthyloxo)cyclophosphazatriene and Dipole Moments of Hexa(aryloxo)cyclophosphazatrienes
Authors: Bandoli Giuliano , Casellato Umberto , Gleria Mario , Grassi Antonio , Montoneri Enzo , Pappalardo Giuseppe C.
Published: March 2015

The crystal and molecular structure of [NP(OC10H7)2]3 was determined by X-ray analysis.

The dipole moments of this compound and of the hexa(phenoxo)cyclotriphosphazatrienes of formula [NP(OC6H3XX′Y)2]3 (X = X′ = H, Y = p-Br; X = m-CH3,. X′ = H. Y = p-Cl; X = X′ = m-CH3, Y = p-Cl; X = X′ = m-CH3, Y = H; X = X′ = H, Y = p-CH(CH3)2; X = X′ = H, Y = p-C(CH3)3) were measured in benzene at 25°C. Crystals of [NP(OC10H7)2]3 are monoclinic with unit cell dimensions a = 24.870(15), b = 7.712(8), c = 27.687(14) Å, β = 115.85(7)°; space group P21/c. The structure was refined to an agreement factor of 0.09. The phosphazene ring deviates (max. deviation 17°) from planarity. and mean distances (A) and angles (°) are P-N 1.58(1). P-O 1.58(1), O-C 1.41(2); P-N-P 120(1), N-P-N 119(1), P-O-C 124(2). The conformations of the naphthyloxo groups at P(2) and P(3) are similar, and different from the group at P(1).

Dipole moment analysis showed that the solid state conformation changes in the solution state. The measured value was in agreement with a symmetric conformation in which at the O-P-O plane each naphthyloxo group is rotated by ca. 40-50° from the anti-coplanar arrangement relative to this plane. The dipole moment data for the p-substituted phenoxo derivatives agree with such a conformation, but the analysis of the dipole moment values of phosphazenes having phenoxo groups bearing more than one substituent group and p-CH(CH3)2 substituent failed to do so due to the inherent limitations of the method.
Notizen: Cyclotriphosphazen-2-spiro-3′ -cyclodi[phosphadiazan] — Eine Spiroverbindung aus Hexachlortriphosphazen und Dihydrazidothiophosphorsäure-O-phenylester / Cyclotriphosphazene-2-spiro-3′-cyclodi[phosphadiazane] — A Spiro Compound from Hexachlorocyclotriphosphazene and Dihydrazidothiophosphoric Acid 0-Phenylester
Authors: Engelhardt Udo , Diefenbach Ursula
Published: March 2015

Hexachlorocyclotriphosphazene (Cl2P=N)3 reacts with dihydrazidothiophosphoric acid 0-phenylester C6H5O—P(=S)(NH—NH2)2 in THF in the presence of triethylamine at room temperature to give the spirocyclic title compound, whose constitution has been confirmed by MS, IR, 31P NMR and elemental analysis.
Untersuchungen an Polypseudohalogeniden, VI / Studies on the Polypseudohalides, VI
Authors: Tebbe Karl-Friedrich , Krauß Norbert
Published: March 2015

The new compound Na[I(CN)2] · 2 H2O can be prepared by addition of iodine to a concentrated aqueous solution of sodium cyanide. It crystallizes in the monoclinic space group P21/c with a = 1044.0(2), b = 480.2(2), c = 730.2(2) pm, β = 95.94(2)° and Z = 2. The crystal structure has been refined to Rf = 0.027 for 692 reflections.

The structure may be described as a layer-like package of cations Na+, water molecules and trihalide-analogous anions [I(CN)2]-. The anion is strictly linear at the I atom and nearly linear at the C atoms with φ(I-C-N) = 176.2° and d(I-C) = 231.1, d(C-N) = 110.6 pm. The cation is surrounded by a slightly distorted octahedron of nitrogen and oxygen atoms with d(Na · · ·N) = 263.8, d(Na · · · O) = 242.0, 242.8 pm
Preparation and Spectroscopic Characterization of trans-Fe(CO)3L1L2 (L1, L2 = Phosphine or Phosphite)
Authors: Inoue Hidenari , Kuroiwa Takeshi , Shirai Tsuneo , Fluck Ekkehard
Published: March 2015

The 57Fe Mößbauer spectra of mixed ligand complexes of the type trans-Fe(CO)3L1L2 (L1 = triphenylphosphine or triphenylphosphite and L2 = phosphine or phosphite) show a quadrupolesplitting doublet typical of the disubstituted iron carbonyls in trigonal bipyramidal symmetry. The inverse linear dependence of the isomer shifts on the CO stretching frequencies is interpreted on the basis of the strengthening triple-bond nature of the carbonyl ligands with increasing iron-to-phosphorus π-back donation. A linear correlation, with a positive slope, between the isomer shifts and the quadrupole splittings has revealed that the phosphorus-to-iron σ-donation is offset by the iron-to-phosphorus π-back donation. A correlation between the coordination shifts and the isomer shifts demonstrates that the iron-to-phosphorus π-back donation plays an important role in the Fe-P bond. The relatively large coupling constant of 2J(P,P) reflects a strong interaction between trans-phosphorus ligands through the P-Fe-P bond
Bildung und NMR-spektroskopische Charakterisierung der Fluorphosphoniumkationen PH4-nFn
+ (n = 1—4) / Formation and NMR Spectroscopic Characterization of the Fluorophosphonium Cations, PH4-nFn
+ (n = 1—4)
Authors: Minkwitz Rolf , Liedtke Andreas
Published: March 2015

The preparations of the salts PH3F+SbF6
- and PHF3
+Sb2F11
- are reported. All fluorophosphonium cations PH4-nFn
+ are characterized by multinuclear (1H, 19F, 31P) NMR spectroscopy. For n > 1 these salts are easily accessible by fluoride abstraction from fluorohydridophosphates(V). PH3F+SbF6
-, however, is obtained in the reaction of PH3F2 with SbF5
Anodische Oberflächen- und Volumenoxidation graphitischer Materialien in neutralen und alkalischen wäßrigen Lösungen / Anodic Surface and Bulk Oxidation of Graphitic Materials in Neutral and Basic Aqueous Solutions
Authors: Besenhard J. O. , Jakob J. , Krebber U. , Möller P. , Sauter R. F. , Kurtze A. , Kanani N. , Meyer H. , Hörber J. K. H. , Jannakoudakis A. D.
Published: March 2015

Anodic oxidation of graphitic materials in aqueous electrolytes is a complex process which may yield e.g. higher stage intercalation compounds and lamellar graphite oxides, acidic surface or defect oxides and gaseous or colloidal decomposition products. Kind and concentration of the electrolyte solution are the most important parameters to control this wide-spread distribution of products. Based on electrochemical and microscopic studies on HOPG and carbon fibres, a mechanistic concept of electrolyte effects is proposed:

In dilute aqueous solutions, attack of OH• radicals formed in the primary electrochemical step is the dominant reaction pathway leading to formation of covalent carbon-oxygen bonds. Due to their reactivity, OH• radicals are able to attack basal plane carbon sites and also to create 3-dimensional defect oxides. Dissociation or capture of OH• radicals - which is favoured in basic and in most concentrated neutral solutions, respectively, - results in less active radical species and limits the attack to thermodynamically less stable carbon atoms at edge sites which may be either oxidized or removed. Due to acidification of the diffusion layer of anodes even in neutral aqueous electrolytes, direct current oxidation always yields higher stage acid intercalation compounds and lamellar graphite oxide as by-products. This can be almost prevented by alternating current oxidation.
Elektrochemische Untersuchungen an Graphitsalzen mit HNO3, HClO4, HReO4 und halogenierten Essigsäuren / Electrochemical Investigations on Graphite Salts with HNO3, HClO4, HReO4 and Halogenated Acetic Acids
Authors: Scharff Peter
Published: March 2015

HNO3, HClO4, HReO4 and CF3COOH have been intercalated into graphite by anodizing pieces of HOPG. Attempts to intercalate ClCH2COOH have failed.

CV measurements and pulsed galvanostatic experiments were performed to ascertain possible side reactions as well as the reversibility of the intercalation process.

Whereas the intercalation reaction proved to be fast in the cases of HNO3, HClO4 and HReO4, it was slow and superposed by side reactions when CF3COOH was used.
5β,6β-Epoxidation of 3β-Cholesteryl Acetate and its Analogues
Authors: Galagovsky L. R. , Burton G. , Gros E. G.
Published: March 2015

The treatment of acetylated Δ5-steroids with chromyl diacetate at low temperature afforded the 5β,6β-epoxy derivatives with stereoselectivity greater than 90 per cent.
Carnivora: The Amino Acid Sequence of the Adult European Polecat (Mustela putorius, Mustelidae) Hemoglobins
Authors: Ahmed Aftab , Jahan Meeno , Braunitzer Gerhard , Pechlaner Helmut
Published: March 2015

The complete amino acid sequences of the hemoglobins from the adult European polecat (Mustela putorius) are presented. The erythrocytes contain two hemoglobin components and three globin chains (α I, α II and β). The primary structure of globin chains and of the tryptic peptides determined in liquid- and gas-phase sequantors. Comparing the sequences of the globin chains of the polecat with that of human Hb-A, 17 (23.9%) substitutions were recognized in the α I, 16 (22.5%) in the α II and 14 (20.4%) in the β chain. A high degree of homology observed with other representatives of the family Mustelidae.
Notizen: Darstellung und Kristallstruktur von Cs4Sn2Se6 / Preparation and Crystal Structure of Cs4Sn2Se6
Authors: Sheldrick W. S. , Braunbeck H. G.
Published: March 2015

The selenostannate(IV) Cs4Sn2Se6 has been prepared by methanolothermal reaction of Cs2CO3 with SnSe2 at 160°C and 13 bar. The [Sn2Se6]4— anions contain two edge-bridged SnSe4 tetrahedra and display crystallographic C2h symmetry. The bridging Sn—Se distances of 2.587(1) are markedly longer than the terminal Sn—Se distances of 2.447(1) and 2.452(2) Å.
Notizen: Cyclophanes, XXX The Crystal Structure of [2.4]Paracyclophane at —95°C
Authors: Jones Peter G. , Pechlivanidis Zissis , Hopf Henning
Published: March 2015

[2.4]Paracyclophane crystallizes in the orthorhombic space group Pbca with cell constants (at —95°C) a = 1151.5(5), b = 1832.9(7), c = 1304.1(4) pm. The structure was refined to R = 0.053 for 1626 unique observed reflections. The aromatic ring systems are inclined to each other at an angle of 21°. The longer bridge is capable of more relaxation than the shorter, as is reflected in the non-bonded distances 279, 386 pm between bridgehead atoms and in the smaller displacements of the associated benzylic carbon atoms from the aromatic ring planes. The central bond length of the longer bridge (151.8 pm) is shorter than would be expected for a single bond.
Verteilung und Valenz der Kationen in Spinellsystemen mit Eisen und Vanadium, VI Gitterkonstanten, Mößbauer-Spektren und elektronische Eigenschaften der Mischkristallreihe ZnFeVO4—Fe2VO4 / Distribution and Valence of the Cations in Spinel Systems with Iron and Vanadium, VI Lattice Constants, Mössbauer Spectra and Electronic Properties of the Solid Solution ZnFeVO4—Fe2VO4
Authors: Riedel Erwin , Ostermann Angela , Kähler Jörg
Published: March 2015

The cation distribution and an energy level diagram of the spinel system ZnFeVO4—Fe2VO4 have been calculated from the lattice constants. The results are in agreement with the Mössbauer spectra. Mössbauer data, Seebeck coefficients and activation energies lead to a model of both tetrahedral and octahedral conduction based on charge hopping. For Zn0.4Fe 1.6VO4 there exists only one iron species. Fe2VO4 has at room temperature the cation distribution Fe0.4
2+Fe0.6
3+(Fe0.6
2+Fe0.4
3+V3+)O4