Published by De Gruyter

Volume 42 Issue 5

Issue of Zeitschrift für Naturforschung B

Contents
Journal Overview

Open Access June 2, 2014

Synthese und Struktur von H₂NSO₂NWCl₄ - ein Kirsanov-Reagens mit einem Übergangsmetallatom / Synthesis and Structure of H₂NSO₂NWCl₄ - a Kirsanov Reagent with a Transition Metal Atom

Michael Witt, Herbert W. Roesky, Mathias Noltemeyer, George M. Sheldrick

Page range: 519-521

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Abstract

H 2 N-SO 2 -NWCl 4 (1) has been synthesized from WCl 6 and SO 2 (NH 2 ) 2 , and forms adducts with donor solvents such as pyridine and acetonitrile. 1·CH 3 CN crystallizes in the space group P2 1 /n with cell constants a = 652.5(1); b = 2325.3(2); c = 775.8(1) pm; β = 90.32(1)°. The nitrogen-tungsten bond length of 173.0 pm and the S-N-W bond angle of 169.3° indicate a W=N double bond.

Open Access June 2, 2014

Hydroxy Complexes of Gold 2. Calcium Aurates [1]

Peter G. Jones, Ralf Schelbach, Einhard Schwarzmann

Page range: 522-524

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Abstract

Two calcium aurate phases have been obtained as single crystals, phase 1 from H AUC1 4 + Ca(OH) 2 and phase 2 from NaAu(OH) 4 + Ca(C10 4) 2 . An X-ray structure determination of 1 shows its composition to be Ca 2 (0H) 3 (H 2 0) 4 [Au(0H) 4 ]. The apparent space group is Cmcm, but this corresponds to a sub-cell of the true structure. The disordered Cmcm structure was refined to R 0.032 for 813 reflections. The coordination geometry is square planar at gold (Au-O 1.97, 1.99 Ä), cubic at Ca(l) and octahedral at Ca(2). Phase 2 crystallizes in a primitive tetragonal cell with a 6.94, c 7.71 Ä; it is probably Ca[Au(OH) 4 ] 2 , but this has not yet been confirmed by a full structure determination.

Open Access June 2, 2014

Stickstoffverbindungen von Elementen der dritten Hauptgruppe mit intra- und intermolekularen Donor-Akzeptor-Bindungen, III [1]. Dynamische Phänomene und Lewis-Säure-Stärke / Nitrogen Compounds of Elements of the Third Main Group with Intra- and Intermolecular Donor Acceptor Bonds, III [1]. Dynamic Phenomena and Lewis Acidity

M. Veith, A. Belo

Page range: 525-535

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Abstract

Compounds of the general formula t BuN(H)-SiMe 2 -N( t Bu)ElX 2 (El = B, X = Me (1m), F (1f), Cl (1c); El = AI, X = Me (2m), Cl (2c), Br (2b); El = Ga, X = Me (3m), Cl (3c), Br (3b); El = In, X = Me (4m), Cl (4c), Br (4b); El = Tl, X = Me (5m)) and t BuN(D)-SiMe 2 -N( t Bu)ElMe 2 (El = Al (2d), Ga (3d), In (4d)) have been characterized by IR and temperature dependent 1 H NMR techniques with respect to their structural changes in solution. A reversible, dynamic, intramolecular equilibrium between two enantiomeric four-membered rings has been established to be responsible for the changes in the spectra. The cyclic form B1, which arises from Lewis acid base interaction of the tert-butyl-amino with the ElX 2 group, transforms to the mirror-image B2 via an acyclic intermediate, in which reorientation of the groups by rotation or inversion can take place. In the boron derivatives (1m, 1c, and 1f) no comparable N-B interaction can be detected. The Lewis acidity of the ElX 2 group deduced from NH wave numbers increases within the following series: TlMe 2 <GaMe 2 ≈InMe 2 <AlMe 2 <GaBr 2 ≈InBr 2 <GaCl 2 ≈AlBr 2 ≈InCl 2 <AlCl 2 . Intramolecular hydrogen transfer from one nitrogen atom to the other can be excluded by comparison of the rate constant k ʜ vs. k ᴅ . The free enthalpy of activation Δ G* depends on the acidity of E1X 2 , the steric requirements and the relative masses of X. The syntheses and characterisation of 1f, 2b, 3b, 4b, 2d, 3d, and 4d are described.

Open Access June 2, 2014

Mn₃Nb₆O₁₁ und Mg₃Nb₆O₁₁ - Darstellung von Einkristallen und Strukturverfeinerung / Mn₃Nb₆O₁₁ and Mg₃Nb₆O₁₁ - Preparation of Single Crystals and Structure Refinement

R. Burnus, J. Köhler, A. Simon

Page range: 536-538

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Abstract

Dark green single crystals of Mg 3 Nb 6 O 11 have been prepared by heating a pellet containing MgO, Nb, Nb 2 O 5 (15:14:8) at 1550 °C in a Nb-container. Single crystals of the isotypic Mn 3 Nb 6 O 11 were formed by heating a mixture of LiF, MnF 2 , Mn, NbO, NbO 2 (1:1:1:1:2) in a corundum crucible at 750 °C. Both compounds crystallize in the trigonal space group P3̄ m 1 (Z = 1) with a = 6.041(1), c = 7.466(1) and a = 6.080(1), c = 7.627(1), respectively. The positional parameters for Mg 3 Nb 6 O 11 are in excellent agreement with those determined by Marinder from powder data.

Open Access June 2, 2014

Alkoxohydridoaluminates. I ²⁷Al NMR Characteristics of (C₄ H₉)₄N⁺ AlH_4-n(OR)_n^- in Benzene

Stanislav Heřmánek, Jiří Fusek, Otomar Kříž, Bohuslav Čásenský, Zbynĕk Černý

Page range: 539-545

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Abstract

The 27 Al NMR spectra of (C 4 H 9 ) 4 N + AlH 4-n (OR) n - prepared in the reaction of (C 4 H 9 ) 4 NAlH 4 with ROH (R = CH 3 , C 2 H 5 , i-C 3 H 7 , t-C 4 H 9 , n-C 5 H 11 , n-C 9 H 19 , cyclo-C 6 U 11 , C 6 H 5 , CH 3 OCH 2 CH 2 ) in benzene show - in contrast to the Li + and Na + salts - a distinct H-splitting, which has allowed to ascertain: 1) the presence of all members (n = 0-4) in solution, 2) the Al chemical shift and AI -H coupling constant of all individual classes, namely (n = 0): 101.6 ppm, quintet 174 Hz; (n = 1): 114-123 ppm, quartet 184-193 Hz; (n = 2): 103-112 ppm, triplet 197-219 Hz; (n = 3): 75-91 ppm, doublet 218-237 Hz; (n = 4): 51-73 ppm, singlet, 3) increased shielding in the order: CH 3 < n-R = i-R = sec-R < C 6 H 11 ⪡ C 6 H 5 < t-C 4 H 9 . The anomalous "sagging" pattern of the curve: δ 27 Al vs. number of OR groups, is interpreted on the basis of significant differences among Al and H and OR in electronegativity.

Open Access June 2, 2014

Darstellung, Kristallstruktur und Eigenschaften von β-Ga₂Br₄ / Preparation, Crystal Structure and Properties of β-Ga₂Br₄

Wolfgang Hönle, Arndt Simon, Gabriele Gerlach

Page range: 546-552

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Abstract

The compounds Ga 2 Br 4 (α+β) have been prepared by reacting GaBr 3 with Ga metal without a solvent or in a hydrocarbon medium. α-Ga 2 Br 4 is isotypic with Ga 2 Cl 4 , and β-Ga 2 Br 4 with Ga2I 4 . Both forms have to be formulated as Ga + (GaBr 4 ) - according to their crystal structures. The first order phase transition α→β has been investigated by means of DTA and temperature dependent X-ray powder photographs. The crystal structure of β-Ga 2 Br 4 has been refined with single crystal data (R3c; a = 2163.4(8) pm; c = 869.2(4) pm; Z = 18; R = 0.037). Main building units are GaBr 4 - tetrahedra (d̄(Ga -Br) = 232.9 pm), connected in three dimensions by capped trigonal prisms (6+2+1) around Ga + . The crystal chemical relationships between β-Ga 2 Br 4 and Ga 2 I 4 are discussed.

Open Access June 2, 2014

Strukturbestimmung von Ga[GaCl₄] und α-Ga[GaBr₄] nach Kristallisation aus Halogenbenzolen / Structure Determination of Ga[GaCl₄] and α-Ga[GaBr₄] Crystallized from Halobenzene Solvents

H. Schmidbaur, R. Nowak, W. Bublak, P. Burkert, B. Huber, G. Müller

Page range: 553-556

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Abstract

Single crystals of Ga[GaCl 4 ] and α-Ga[GaBr 4 ] have been obtained by crystallization from chlorobenzene and bromobenzene, respectively. The crystal structures of the two compounds, determined previously only on the basis of photographic data, were refined to a more satisfactory level of accuracy. The results confirm the presence of tetrahedral GaX 4 - anions as thecounterions to dodecahedrally coordinated Ga + cations. The gallium-halogen distances in these dodecahedral arrays fall into four classes, thus resulting in a significant asymmetry of the Ga(I) center. This deviation from ideal S 4 symmetry is also apparent in the 69 Ga NMR spectra of the crystalline powder samples. Approximate calculation of the data leads to asymmetry parameters (η) of 0.44 and 0.27 for the chloride and bromide, respectively. Crystal data Ga[GaCl 4 ]: Pnna (#52), a = 7.200(1), b = 9.625(1), c = 9.498(1) Å; Z = 4. For α-Ga[GaBr 4 ]: Pnna, a = 7.528(1), b = 9.972(1), c = 10.010(1) Å, Z = 4.

Open Access June 2, 2014

Al₇Te₁₀ — das erste Chalcogenid mit zweiwertigem Aluminium / Al₇Te₁₀ — the First Chalcogenide of Divalent Aluminum

Reinhard Nesper, Jan Curda

Page range: 557-564

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Abstract

Al 7 Te 10 is prepared from a melt of the elements in stoichiometric amounts in a corundum crucible contained in a sealed quartz ampoule. The ruby red cube shaped crystals are stable below 840 K. The structure of Al 7 Te 10 (R32-D 3 7 a = 1439.5 pm, c = 1793.2 pm, Z = 6, R = 0.03) is a distorted defect variant of a tetrahedral arrangement of the 4H-polytype. The central unit, a double barrelane [Te 4 Al 4 -Al 4 Te 4 ], contains an Al -Al bond of 260 pm, which is somewhat longer (n = 0.83) than an expected single bond (250 pm, n = 1). This homopolar bond disturbs the electrostatically favorable (Al-Te-) n sequence in the structure which is compensated by the occurrence of four-membered Al 2 Te 2 rings. Al 7 Te 10 is a Zintl phase according to 1/2{[Al 2+ -Al 2+ ][Al 3+ ] 12 [Te 2- ] 20 } and exhibits semiconducting and diamagnetic behaviour.

Open Access June 2, 2014

[Fe₆Se₉(SR)₂]^4- Clusters (R = Me, CH₂Ph): Synthesis and Characterization, and the X-Ray Structure of (PhCH₂NEt₃)₄[Fe₆Se₉(SMe)₂]

Henry Strasdeit, Bernt Krebs, G. Henkel

Page range: 565-572

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Abstract

(1) The compounds (PhCH 2 NEt 3 ) 4 [Fe 6 Se 9 (SMe) 2 ] and (Et 4 N) 4 [Fe 6 Se 9 (SCH 2 Ph) 2 ] (2) have been isolated in good yields from Fe(SR) 3 (R = Me, CH 2 Ph)/“Na 2 Se 2 ” reaction mixtures in methanol/N,N-dimethylformamide after addition of the appropriate tetraalkylammonium chlorides. 1 is monoclinic, space group P2 1 /c, Z = 4, with a = 18.697(14), b - 22.606(16), c = 15.989(11) Å, and β = 94.15(6)° at 140 K. Its structure has been refined to R (R w ) = 0.092 (0.075). The [Fe 6 Se 9 (SMe) 2 ] 4- anion contains six coplanar iron atoms which are present in distorted tetrahedral Se 4 and Se 3 (SMe) ligand surroundings. The Se atoms are μ, μ 3 and μ 4 bridging. The four central Fe atoms and the Se atoms constitute a Fe 4 Se 9 group that is structurally related to 1 ∞ [Fe 2 Se 3 ] 2- double tetrahedral chains and 2 ∞ [FeSe] layers. The Fe atoms in the [Fe 6 Se 9 (SMe) 2 ] 4- cluster are antiferromagnetically coupled. 1 has a room-temperature magnetic moment of 1.22 μ B /Fe. Cyclic voltammograms, and electronic, infrared, and proton resonance spectra of 1 and 2 have been measured.

Open Access June 2, 2014

Infrared, ⁵⁷Fe Mössbauer, and ³¹P NMR Spectroscopic Characterization of Fe(CO)₄L (L = Phosphine and Phosphite)

Hidenari Inoue, Takashi Nakagome, Takeshi Kuroiwa, Tsuneo Shirai, Ekkehard Fluck

Page range: 573-578

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Abstract

A series of trigonal bipyramidal Fe(CO) 4 L complexes has been prepared and characterized by infrared, 57 Fe Mössbauer and 31 P NMR spectroscopy. A linear correlation, with a negative slope, between the CO stretching frequencies and the isomer shifts demonstrates that the triple bond nature of the carbonyl ligands is strengthened with increasing iron-to-phosphorus back donation. The linear dependence of the quadrupole splittings on the isomer shifts with a positive slope has revealed that the σ-donor capability of the phosphine or phosphite ligand is offset by the π-acceptor capability. The formation of Fe(CO) 4 L complexes from the corresponding free ligands is accompanied by a downfield shift of 31 P NMR chemical shifts. The coordination shifts are linearly correlated with the Mössbauer isomer shifts.

Open Access June 2, 2014

PH-funktionelle Phosphane mit α- und β-ständigen 2-Pyridylsubstituenten 2-C₅H₄N—[CH₂]_n—PRH (R = H, iPr, tBu, Ph, 2-C₅H₄N-[CH₂]_n; n = 1, 2) / PH-Functional Phosphanes with 2-Pyridyl Substituents in α- or β-Position 2-C₅H₄N —[CH₂]_n—PRH (R = H, iPr, tBu, Ph, 2-C₅H₄N-[CH₂]_n; n = 1,2)

Gerd U. Spiegel, Othmar Stelzer

Page range: 579-588

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Abstract

PH-functional phosphanes containing a 2-pyridyl substituent in α- or β-position to phosphorus, e.g. 2-C 5 H 4 N - [CH 2 ] n -PRH (R = H, iPr, tBu, Ph; n = 1,2) have been obtained. The reactivity of the PH-groups can be employed for the synthesis of tridentate NPN-hvbrid donors. [2-C 5 H 4 N -CH 2 -CH 2 ] 2 PR (R = H. Ph). The phosphanes 2-C 5 H 4 N-[CH 2 ] n -PRH behave as monodentate ligands in transition metal complexes and form labile chelate ring systems. They may bridge metal-metal bonds to form seven membered ring systems, e.g. Mo 2 PC 3 N. The coordination of the N-donor of the ligands 2-C 5 H 4 N - [CH 2 ] n -PRH to a transition metal atom is indicated by a lowfield shift and a small 31 P - 13 C-splitting of the 13 C{ 1 H} NMR signal of carbon atom 6 in the pyridin ring system.

Open Access June 2, 2014

Reaktion von Oxomolybdän-Komplexen mit Alkyldithiocarbazaten. Darstellung und Charakterisierung von Hydrazido- und Diazenido-Komplexen des Molybdäns / Reaction of Oxomolybdenum Complexes with Alkyldithiocarbazates. Synthesis and Characterization of Hydrazido- and Diazenido Complexes of Molybdenum

Rainer Mattes, Heinz Scholand, Ulrich Mikloweit, Volker Schrenk

Page range: 589-598

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Abstract

(2). The reaction of alkyldithiocarbazates NH 2 NHC(S)SR′ with MoO 2 (S 2 CNR 2 ) 2 R, R′ = Me, Et) yields the diazenido hydrazido complexes Mo(NNC(S)SR′)(NH 2 NC(S)SR′)(S 2 CNR 2 ) 2 (1), reaction with the molybdenum hydroxylamidate complex MoO 2 (ONMe 2 ) 2 gives the diazenidobis( hydrazido) complex Mo(NNC(S)SMe)(NH 2 NC(S)SMe) 2 (Me 2 NO)-CH 3 OH The crystal structures of 1 a (R = Me, R′ = Et) and 2 have been determined. The metal atoms in 1 a and 2 are seven coordinated and have MoN 2 S 5 and MoN 3 O 2 S 2 ligand arrays, respectively. Both compounds contain the approximately linear diazenido ligand NNC(S)SR in addition to one (1a) or two (2) N,S-chelating hydrazido(1-) ligands NH 2 NC(S)SR. When 1a is treated with HCl, the dimeric complex (Me 2 NCS 2 )(O)Mo(μ-NNC(S)SEt) 2 Mo(S 2 CNMe 2 ) (4) is obtained. X-ray crystallography showed 4 to be an asymmetric dinuclear complex, with a Mo-Mo distance of 267.2(1) pm. One Mo site has a square pyramidal MoOS 2 N 2 geometry, while the other one has an approximately trigonal prismatic MoN 2 S 4 geometry. The mean N-N distance in 4 is 135(1) pm. The reaction of NH 2 NHC(S)SMe with MoO 2 (acac) 2 yields Mo(Me 2 CNNC(S)SMe)(NNC(S)SMe)(MeSC(S)NNC(S)SMe) (3). Its structure has been determined by X-ray crystallography. 3 contains a unique combination of three different N- and S-chelating ligands: the Schiff base Me 2 C=NNC(S)SMe, the highly bent bidentate diazenido ligand NNC(S)SMe (∡ Mo-N-N = 142.1(5)°), and the novel planar tridentate ligand MeSC(S)NNC(S)SMe. The latter can be taken as neutral diacyldiazene or, more likely, as the dianion of the as yet unknown MeSC(S)NH -NHC(S)SMe. The N - N distance in this ligand is 136.1(9) pm.

Open Access June 2, 2014

Reaktion von DioxomoIybdän(VI)-Komplexen mit O-Methyl-thiocarbazat Darstellung und Charakterisierung von Schiffbase-, Hydrazido- und Diazenido-Komplexen des Molybdäns / Reaction of Dioxomolybdenum(VI) Complexes with O-Methylthiocarbazate Synthesis and Characterization of Schiffbase, Hydrazido and Diazenido Complexes of Molybdenum

Rainer Mattes, Heinz Scholand, Ulrich Mikloweit, Volker Schrenk

Page range: 599-604

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Abstract

trans The reaction of NH 2 NHC(S)OR, (R = Me, Et) with MoO 2 (acac) 2 yields the dimeric complexes MO 2 O 3 (MeC(O)CHC(Me)NNC(S)0R) 2 (1) with the planar O = Mo - O - Mo = O group. The tetradentate O,N,S-donor ligand is formed through condensation of acetylacetone with the organohydrazine. The reactions of NH 2 NHC(S)OMe with MoO 2 (S 2 CNEt 2 ) 2 and MoO 2 (ONEt 2 ) 2 give the diazenido hydrazido complexes Mo(NNC(S)OMe)(NH 2 NC(S)OMe)(S 2 CNEt 2 ) 2 ·CH 2 Cl 2 (2) and Mo(NNC(S)OMe)(NH 2 NC(S)OMe) 2 (ONEt 2 ) (4). The metal atoms in both compounds are seven coordinated and contain the approximately linear diazenido ligand NNC(S)OMe and one (2) or two (4) N,S-chelating hydrazido(1-) ligands NH 2 NC(S)OMe. 2 has crystallographically imposed mirror symmetry. Recrystallization of 2 from toluene in air gives the asymmetric dinuclear complex (Et 2 NCS 2 )(O)Mo(μ-NNC(S)OMe) 2 Mo(S 2 CNMe 2 ) (3). The Mo-Mo distance is 267.0(2) pm. One Mo site has square pyramidal MoOS 2 N 2 geometry, the other trigonal prismatic MoN 2 S 4 geometry. The coordination of the bridging N atoms is slightly pyramidal. The compounds 1, 2 and 3 have been further characterized by vibrational spectroscopy.

Open Access June 2, 2014

Ein neuer Weg zur Darstellung der Nitrosylkomplexe CpM(CO)₂NO (M = Cr/Mo/(W)) durch NO/CO-Austausch zwischen [Co(NO)₂Hal]₂ und Carbonyl-cyclopentadienylkomplexen* / A Novel Route to the Nitrosyl Complexes CpM(CO)₂NO (M = Cr/Mo/(W)) by NO/CO Exchange between [Co(NO)₂Hal]₂ and Carbonyl-cyclopentadienyl Complexes*

Anke Brauel, Dieter Rehder

Page range: 605-609

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Abstract

The title compounds have been prepared by NO transfer from [Co(NO) 2 Hal] 2 (Hal = Cl, Br, I) to [CpM(CO) 3 ]2, CpM(H)(CO) 3 and [CpM(CO) 3 ] - (M = Cr, Mo, W; Cp = η 5 -C 5 H 5 ). In the case of the neutral complexes, the reactions need initiation and support by light; the anionic complexes are nitrosylated in a dark reaction. The highest yields (60%) are obtained from the reactions between [Co(NO) 2 Br] 2 and [CpM(CO) 3 ] 2 (M = Cr, Mo).

Open Access June 2, 2014

Synthesis and Photoelectron Spectroscopy of Spin Labeled Metal Complexes

Dekang Shen, Lizhi Zhu, Liangzhong Zhao

Page range: 610-612

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Abstract

(4) Two new spin labeled metal complexes; cobalt(II) bis(2,2,6,6-tetramethyl-1-oxyl-4-piperidyl p-salicylaldiminobenzoate) (3), copper(II) bis(2,2,6,6-tetramethyl-1-oxyl-4-piperidyl-p-salicylaldiminobenzoate) were prepared. The synthesis of amino derivatives of nitroxide compounds were improved by a simplified synthetic route. The XPS spectra of 3 and 4 were determined. The observed N Is, Cu 2p and Co 2p spectra of spin labeled metal complex are discussed.

Open Access June 2, 2014

Synthesis of Some New 2-Imino-2,3-dihydro-1,3,4-thiadiazole and Selenadiazole Derivatives

Abdou Osman Abdelhamid, A. S. Shawali

Page range: 613-616

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Abstract

(2) Diazotized 3(5)amino-5(3)-phenylpyrazole reacts with phenacylthiocyanate (1) and phenacylselenocyanate (10) to give the corresponding 1,3,4-thiadiazoline derivative (5) and 1,3,4- selenadiazoline derivative (12), respectively. A mechanism is proposed and it is substantiated by an alternate synthesis of 5 and 12 from the corresponding hydrazidoyl bromide (6) with potassium thiocyanate and potassium selenocyanate, respectively. The thiadiazoline (5) and selenadiazoline (12) give the respective N-acyl derivatives (7a) and (12) with acetic anhydride. Nitrosation of 5 and 12 gives the corresponding N-nitroso-derivatives (8a) and (14), respectively. Cyclization of 6 gives the corresponding 9 with triethylamine in benzene.

Open Access June 2, 2014

Synthese und Absolute Konfiguration von (+)-1-Amino-2-propanthiol·HCl / Synthesis and Absolute Configuration of ( + )-1-Amino-2-propanethiol · HCl

Sigurd Elz, Martin Dräger, Hans-Joachim Sattler, Walter Schunack

Page range: 617-622

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Abstract

)-4a- The structure of (-)-5-methyl-2-phenylthiazolidine (( -)-4a), an intermediate in the synthesis of (+)-1-amino-2-propanethiol · HCl ((+)-2 · HCl), was elucidated by 1 H and 13 C NMR spectroscopy. In contrast to earlier findings it was shown that the important intermediate ( -)-4a is not a single diastereomer but represents a 1:1 mixture of (2R,5Sand ((2S,5S )-4a -diastereomers. The absolute configuration of the (2S,3S)-di-O-(4-toluoyl)tartrate of the disulfide (5) derived from (+)-2 · HCl was determined to be (S,S) using X-ray technique.

Open Access June 2, 2014

The Reaction of Malononitrile with Some Enamines of 1-Indanone Synthesis of o-Aminonitriles of Indenopyridine and Indenothiopyran

Krystyna Bogdanowicz Szwed, Hanna Feret, Małgorzata Lipowska

Page range: 623-627

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Abstract

(4). The reaction of enamines of 1-oxo-indan-2-carboxylic acid anilides (1) with malononitrile yielded 2-arylcarbamylindenylidene-malononitriles (3), which in alkaline solution underwent cyclization to indenopyridines Enamines of 1-oxo-indan-2-carbothionic acid anilides (2) reacted with malononitrile yielding indenothiopyrans (6), which under influence of alkalis were transformed to indenopyridines (8).

Open Access June 2, 2014

Neuartige discotisch-flüssigkristalline, polare Monothioscyllitol-Derivate [1,2] / Novel Discotic Liquid Crystalline, Polar Monothioscyllitol Derivatives [1,2]

Bernd Kohne, Peer Marquardt, Klaus Praefcke, Panicos Psaras, Werner Stephan

Page range: 628-642

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Abstract

3-5 On the basis of an improved synthesis of the 1,3,4,5,6-pentaacetate of myo-inositol, now available in only one step from that cyclitol in yields up to 90%, we prepared various derivatives of 1-deoxy-1-mercapto-scyllo-inositol (monothioscyllitol) via the mesylate 1 a or the trifluoromesylate 1 b , respectively. The non-centrosymmtric disc-shaped thioethers 3a-h as well as their S,S-dioxides 4a-h and the S-oxide 5f exhibit thermotropic discotic mesophases over wide temperature ranges. The thermomesomorphism of these new sulfur compounds has been studied by optical microscopy and by differential scanning calorimetry. The pentabutyrates 3a and 4a as well as the dimesomorphic pentapentanoate 3 b exhibit a probably new type of discophase D x whereas all other monothioscyllitol derivatives with longer alkyl chains show the D ho -phase over wide temperature ranges. Of some selected new thioethers 3, sulfones 4, and of the sulfoxide 5f the dipole moments have been measured which are highest with the cyano derivatives 3g and 4g at about 5 or above 6 D, respectively. These values characterize them as the strongest polar discogens studied so far. The presented monothioscyllitol derivatives 3, 4 and 5 do not only increase the number of rarely known polar discogens, but also show that non-centrosymmetric and polar discotic liquid crystals with a small, alimonocyclic, saturated "core" now can be prepared easily. Their permanent electric dipole moments could give rise to interesting magnetic or electric field effects.

Open Access June 2, 2014

Chemie an starren Grenzflächen, 7 [1] Ausgewählte Beispiele der chemischen Grenzflächenmodifizierung von Aerosil / Chemistry at Rigid Surfaces, 7 [1] Selected Examples of the Chemical Surface Modification of Aerosil

Leopold Horner, Hans Ziegler

Page range: 643-660

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Abstract

Aminoaerosil containing primary amino end groups is obtained according (1) by reaction of aerosil with γ-triethoxysilylpropyl amine (Table II). The NH 2 -anchor groups are acylated in the usual manner: carbonic acid anhydrides, acid chlorides and acid azides and by application of the carbodiimide method (Table III). Optically active groups and phosphoric acid diestergroups are covalently linked with the surface of aerosil according (2) and (3). Aminoaerosil reacts with vinylsulfones as anchor groups of dyes (Remazol- Dyes) producing a covalent bond according (6). Functional groups linked to the surface of aerosil react “normal” (with respect to homogenous solutions) with group specific reagents. Examples: bromination, ozonization of C-C double bonds, hydrolysis of phosphoric acid esteramidates and surface bound chloroamine-T groups. "Interparticular" reactions of modified aerosil are not observed. But aerosil with electroactive groups are electroreduced using Hg- or Pb-electrodes. The optical induction of the catalytic hydrogenation of prochiral defines using palladium deposited on chiral modified aerosil surfaces is low (ca. 1%). Some analytical methods are presented, which are recommended for the determination of the amount of functional groups bound to the surface.

Open Access June 2, 2014

Amphiphilic Carbohydrate-Based Mesogens, 2 [1] Aldose Di-n-alkyl Dithioacetals: Novel Double-Tailed Thermotropic Liquid Crystals

Wilhelm Volker Dahlhoff

Page range: 661-662b

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Abstract

Mercaptolyses of the pentoses [D-lyxose (1), D-xylose (2), L-arabinose (3)] and hexoses [D-mannose (4), D-glucose (5), D-galactose (6)] with n-alkyl thiols having chain lengths ≥ C 6 gives mesogenic aldose di-n-alkyl dithioacetals 7-12.

About this journal

Objective
Zeitschrift fuer Naturforschung B (ZNB) publishes novel research in all areas of inorganic chemistry, organic chemistry, and analytical chemistry. In particular, the journal focuses on solid state chemistry, coordination chemistry, main group element chemistry, synthetic organic chemistry, natural product chemistry and, to a lesser extent, on analytical chemistry. For more than 65 years Zeitschrift fuer Naturforschung B has been open to contributions from all fields of experimental and theoretical chemistry. Zeitschrift fuer Naturforschung B publishes 12 issues per volume/year. Sometimes double issues occur.

Topics

Solid state chemistry
Coordination chemistry
Main group element chemistry
Organic chemistry
Natural product chemistry

Article formats
Original (full) papers, research notes and preliminary communications, reports on specific research topics of current interest (reviews)

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Volume 42 Issue 5

Issue of Zeitschrift für Naturforschung B

Synthese und Struktur von H2NSO2NWCl4 - ein Kirsanov-Reagens mit einem Übergangsmetallatom / Synthesis and Structure of H2NSO2NWCl4 - a Kirsanov Reagent with a Transition Metal Atom

Abstract

Hydroxy Complexes of Gold 2. Calcium Aurates [1]

Abstract

Abstract

Mn3Nb6O11 und Mg3Nb6O11 - Darstellung von Einkristallen und Strukturverfeinerung / Mn3Nb6O11 and Mg3Nb6O11 - Preparation of Single Crystals and Structure Refinement

Abstract

Alkoxohydridoaluminates. I 27Al NMR Characteristics of (C4 H9)4N+ AlH4-n(OR)n- in Benzene

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Darstellung, Kristallstruktur und Eigenschaften von β-Ga2Br4 / Preparation, Crystal Structure and Properties of β-Ga2Br4

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Strukturbestimmung von Ga[GaCl4] und α-Ga[GaBr4] nach Kristallisation aus Halogenbenzolen / Structure Determination of Ga[GaCl4] and α-Ga[GaBr4] Crystallized from Halobenzene Solvents

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Al7Te10 — das erste Chalcogenid mit zweiwertigem Aluminium / Al7Te10 — the First Chalcogenide of Divalent Aluminum

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[Fe6Se9(SR)2]4- Clusters (R = Me, CH2Ph): Synthesis and Characterization, and the X-Ray Structure of (PhCH2NEt3)4[Fe6Se9(SMe)2]

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Infrared, 57Fe Mössbauer, and 31P NMR Spectroscopic Characterization of Fe(CO)4L (L = Phosphine and Phosphite)

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PH-funktionelle Phosphane mit α- und β-ständigen 2-Pyridylsubstituenten 2-C5H4N—[CH2]n—PRH (R = H, iPr, tBu, Ph, 2-C5H4N-[CH2]n; n = 1, 2) / PH-Functional Phosphanes with 2-Pyridyl Substituents in α- or β-Position 2-C5H4N —[CH2]n—PRH (R = H, iPr, tBu, Ph, 2-C5H4N-[CH2]n; n = 1,2)

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Reaktion von Oxomolybdän-Komplexen mit Alkyldithiocarbazaten. Darstellung und Charakterisierung von Hydrazido- und Diazenido-Komplexen des Molybdäns / Reaction of Oxomolybdenum Complexes with Alkyldithiocarbazates. Synthesis and Characterization of Hydrazido- and Diazenido Complexes of Molybdenum

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Synthesis and Photoelectron Spectroscopy of Spin Labeled Metal Complexes

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Synthesis of Some New 2-Imino-2,3-dihydro-1,3,4-thiadiazole and Selenadiazole Derivatives

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Synthese und Absolute Konfiguration von (+)-1-Amino-2-propanthiol·HCl / Synthesis and Absolute Configuration of ( + )-1-Amino-2-propanethiol · HCl

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The Reaction of Malononitrile with Some Enamines of 1-Indanone Synthesis of o-Aminonitriles of Indenopyridine and Indenothiopyran

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Neuartige discotisch-flüssigkristalline, polare Monothioscyllitol-Derivate [1,2] / Novel Discotic Liquid Crystalline, Polar Monothioscyllitol Derivatives [1,2]

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Chemie an starren Grenzflächen, 7 [1] Ausgewählte Beispiele der chemischen Grenzflächenmodifizierung von Aerosil / Chemistry at Rigid Surfaces, 7 [1] Selected Examples of the Chemical Surface Modification of Aerosil

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Amphiphilic Carbohydrate-Based Mesogens, 2 [1] Aldose Di-n-alkyl Dithioacetals: Novel Double-Tailed Thermotropic Liquid Crystals

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Synthese und Struktur von H₂NSO₂NWCl₄ - ein Kirsanov-Reagens mit einem Übergangsmetallatom / Synthesis and Structure of H₂NSO₂NWCl₄ - a Kirsanov Reagent with a Transition Metal Atom

Mn₃Nb₆O₁₁ und Mg₃Nb₆O₁₁ - Darstellung von Einkristallen und Strukturverfeinerung / Mn₃Nb₆O₁₁ and Mg₃Nb₆O₁₁ - Preparation of Single Crystals and Structure Refinement

Alkoxohydridoaluminates. I ²⁷Al NMR Characteristics of (C₄ H₉)₄N⁺ AlH_4-n(OR)_n^- in Benzene

Darstellung, Kristallstruktur und Eigenschaften von β-Ga₂Br₄ / Preparation, Crystal Structure and Properties of β-Ga₂Br₄

Strukturbestimmung von Ga[GaCl₄] und α-Ga[GaBr₄] nach Kristallisation aus Halogenbenzolen / Structure Determination of Ga[GaCl₄] and α-Ga[GaBr₄] Crystallized from Halobenzene Solvents

Al₇Te₁₀ — das erste Chalcogenid mit zweiwertigem Aluminium / Al₇Te₁₀ — the First Chalcogenide of Divalent Aluminum

[Fe₆Se₉(SR)₂]^4- Clusters (R = Me, CH₂Ph): Synthesis and Characterization, and the X-Ray Structure of (PhCH₂NEt₃)₄[Fe₆Se₉(SMe)₂]

Infrared, ⁵⁷Fe Mössbauer, and ³¹P NMR Spectroscopic Characterization of Fe(CO)₄L (L = Phosphine and Phosphite)