bluuebunny/crossref_metadata_2025_split huggingface dataset:
Struktur und X-X-Elektronendichteverteilung in Diaminoboranen des Typs (RCH3N)2BCH3 mit R = H, CH3
Authors: Niederprüm Norbert , Boese Roland , Schmid Günter 
Published: March 2015

Using a miniature zone melting device with focused infrared light it was possible to grow crystals of bis(dimethylamino)methylborane (1) and bis(monomethylamino)methylborane (2) at temperatures o f 182 K and 177 K, respectively. The crystal structure and the X - X difference electron density have been determined at temperatures o f 120 K (1) and 115 K (2).
1 crystallizes in the orthorhombic space group Pbca with a = 758.87(7), b = 1559.74(12) and c = 1296.73(12) pm. The mean B - N distance is 143.1(3) pm.
2 crystallizes in the monoclinic space group P21/c with a = 775.06(6), b = 1533.94(17), c = 1011.06(10) pm and β = 102.669(7)° with intermolecular N ··· H hydrogen bridges. The mean B - N distance is 141.5(2) pm.
It is shown that the variation of torsion angles at small angles has more influence on bond lengths than the same or a greater variation at large angles and that it is necessary to pay more attention to the torsion angles ( C - B - N - C ) rather than to the interplanar angles (plane N ,B,N - plane N ,C,C ).
Synthese und Kristallstruktur eines 1(λ5),4(λ5)-Diphosphaazulens sowie dreier 1 -Phospha-1,6a-dihydropentalene / Synthesis and Crystal Structure of a 1(λ5),4(λ5)-Diphosphaazulene and of Three 1 -Phospha-1,6a-dihydropentalenes
Authors: Silberzahn Jürgen , Pritzkow Hans , Latscha Hans Peter 
Published: March 2015

The reaction of acetylene-bis(phosphonous-bisdimethylamide) (1) with tetraphenyl-cyclopentadienone (2) yields a 1-phospha-1,6a-dihydropentalene (4), which can be sulfurized with CS2 to give the 1-thio-compound 5, and oxidized with H2O2 to give the 1-oxo-compound 6.
With dimethyl-acetylenedicarboxylate (7) an amazingly stable l (λ5),4(λ5)-diphosphapentalene (8) is generated, which reacts further with 7 to yield a l(λ5),4(λ5)-diphosphaazulene (9).
The preparation of the new molecules 4, 5, 6, 9 and the crystal structures of 5 and 9 are reported.
Hydrocobaltierung von 1,3-Dihydro-1,3-diborafulven-Derivaten HCo(CO)4/Hydrocobaltation of 1,3 - Dihydro - 1,3 - diborafulvene Derivatives with HCo(CO)4
Authors: Nagy-Magos Zsuzsa , Enders Markus , Pritzkow Hans , Siebert Walter 
Published: March 2015

(3)
Hydrocobaltation reactions of 1,3-dibora-4,5-benzofulvene (2) and 1,3-dibora[5]radialene with HCo(CO)4 lead to the complexes tricarbonyl-(η5-4,5-benzo-2-isopropyl-1,3-dimethyl- 2,3-dihydro-1,3-diborolyl)cobalt (4) and tricarbonyl-(η5-isopropenyl-2,5-diisopropyl-1,3-dimethyl-1,3-dihydro-1,3-diborolyl)cobalt (5) in 24% and 5% yield, respectively. The constitution of 4 and 5 follows from the spectroscopic data, and is proven by an X-ray structure analysis of 4. The formation of 5 is accompanied by a 1,5-hydrogen shift in the 1.3-dibora[5]radialene (3).
Crystal Structures of mer-Cr(pyridine)3(N3)3 and Polymeric NaCr(pyridine)4(N3)4. A Structure Containing μ(1,3) Bridging Azido Ligands between Chromium-and Sodium-Centered Polyhedra
Authors: Goher Mohamed A. S. , Abu-Youssef Morsy A. M. , Mautner Franz A. 
Published: March 2015

The structures of mer-Cr(py)3(N3)3 (1) and polymeric NaCr(py)4(N3)4 (2) were determined by X-ray crystallography. Crystal data; 1, C15H15N12Cr, triclinic, space group P1̄, a = 895.3(2), b = 999.1(3), c = 1269.9(5) pm , α = 106.76(3), β = 96.69(3), γ = 116.30(2)°, V = 943.8(6) · 106 pm3, Z = 2 and Rw = 0.038 for 1736 observed MoKα diffractometer data; 2, C20H20N16CrNa, monoclinic, space group C2/c, a = 1561.2(3), b = 1028.8(2), c = 1573.6(4) pm, β = 90.70(2)°, V = 2 527.3(9) · 106 pm3, Z = 4 and = 0.033 for 1272 MoKα diffractometer data.
The coordination around the chromium (III) ion in the discrete molecules of 1 is six-coordinate with mean distances Cr-N(py) of 210.2(4) pm and Cr-N(N3) of 200.8(4) pm. The terminal azido ligands are almost linear and asymmetric, the N-N bonds nearer to the metal (118.8(6) to 120.5(7) pm) being significantly longer than the terminal ones (114.7(7) to 115.5(7) pm). In compound 2, each chromium or sodium cation is six-coordinated by four azido groups and two pyridine molecules. The azido groups act as μ(1,3) bridging ligands between chromium and sodium octahedra to form a three-dimensional network structure. The chromium atoms are trans-coordinated by the pyridine ligands whereas the sodium cations are cis-coordinated.
Flavonoids from Three Ethiopian Species of Premna
Authors: Habtemariam Solomon , Gray Alexander I. , Waterman Peter G. 
Published: March 2015

Two novel hepta-oxygenated flavonols have been isolated from the aerial parts of Premna
oligotricha and identified, primarily on the basis of N M R spectroscopy, as 3,5,5'-trihydroxy- 6,7,3',4'-tetram ethoxyflavone (2) and 3,5,7,5'-tetrahydroxy-6,3',4'-trim ethoxyflavone (3). Known flavonoids, with lower levels of oxygenation were obtained from two other Premna
species, P. schimperi and P. recinosa.
Reaktionen von Germylenen mit Säureaziden / Reactions of Germylenes with Acid Azides
Authors: Meller Anton , Ossig Günter , Maringgele Walter , Noltemeyer Mathias , Stalke Dietmar , Herbst-Irmer Regine , Freitag Stefanie , Sheldrick George M. 
Published: March 2015

A, B
Starting materials are the sterically hindered diazagermylenes and C o f the general formula [R (Me3Si)N]2Ge (R = o-disubstituted aryl or mesityl). A and B react with arylsulfonylazides to give the polymeric N ,N -bis(amino)-N '-sulfonylgermazane derivatives 1 and 2. With phenylazidoformiate, A, B and C yield the corresponding diamino(phenoxy)(isocyanato)- germanium (IV ) derivatives 3 -5, while with N ,N -dimethylcarbamoylazide the impure diamino(dimethylamino)(isocyanato)germanium (IV ) com pound 6 is formed. Reactions of A and B with O ,O -diphenyl-phosphorylazide afford the eight-membered (GeNPO)2 ring compounds 7 and 8
. The substances are characterized by C, H , N analyses, 1 - 8 by their mass spectra, and 3 - 8 by NMR ( 1H, l3C, 29Si, 31P). Characteristic IR group frequencies are given for the isocyanato compounds 3 - 6 . Single crystal X -ray structure analyses are reported for C, 4, 5 and 8 .
Reaktion von N-Trimethylsilyl-N′(N″ -trimethylsilylammodiphenylphosphoranylidenimino) sulfamid mit Wolframoxitetrachlorid und die Struktur von (Cl3WNPPh2N)2 Reaction of N-Trimethylsilyl-N′(N″ -trimethylsilylaminodiphenylphosphoranylidene)sulfamide with Tungstenoxitetrachloride and the Structure of (Cl3WNPPh2N)2
Authors: Roesky H. W. , Raubold T. , Noltemeyer M. , Witt M. , Bohra R. 
Published: March 2015

1
The reaction of ClSO2N = PPh2Cl () with NH3 yields H2NSO2N = PPh2NH2 (2).This compound is converted to Me3Si(H)NSO2N = PPh2N(H)SiMe3 (3) by Me3SiNMe2. 3 reacts with WOCl4 under elimination of (Me3Si)2O and ClSO2NH2 to yield the eight-membered ring system (Cl3WNPPh2N)2 (4).The molecular structure of 4 was investigated by an X-ray structure analysis.
Über Verbindungen subvalenter Hauptgruppenmetallkationen mit Dithiolaten, 5. Mitteilung. Die Kristallstruktur von (AsPh4)2[Te(S2C = C(CN)2)2] und ab initio-Berechnungen an [Te(S2C =C(CN)2)2]2- / Compounds of Subvalent Main Group Cations with Dithiolates, Part 5. Crystal Structure of (AsPh4)2[Te(S2C = C(CN)2)2] and ab initio Calculation of [Te(S2C = C(CN)2)2]2-
Authors: Hummel Hans-Ulrich , Fischer Thomas , Moll Matthias , Wolski Alexander , Otto Peter , Dietzsch Wolfgang 
Published: March 2015

Abstract
The crystal structure of (AsPh4)2[Te(S2C = C(CN)2)2] has been determined by X-ray diffrac tion and the electronic structure has been calculated using an effective core potential approach for core electrons of Te and minimal basis-sets for valence electrons of Te and electrons of S, C and N. Te is situated in the center of planar [Te(S2C = C(CN)2)2]2- anions and is coordinated by four sulfur atoms in a trapezoid geometry with Te -S distances of 2.463(4), 2.524(4), 2.819(4) and 2.945(3) Å. The compound crystallizes in the triclinic space group P 1̄ with a = 9.562(5), b = 11.430(6), c = 27.319(20) Å, α = 93.248(2), β = 91.06(2), γ = 112.23(4)° and Z = 2. The trapezoid geometry allows a straightforeward mixing of Te 5 s-and one 5p-orbital giving rise to the formation of sp-hybride orbitals.
Röntgenographische, elektrische und spektroskopische Untersuchungen an den Palladiumchalkogeniden PdS1-xSex / Roentgenographic, Electrical and Spectroscopic Investigations of the Palladium Chalcogenides PdS1-xSex
Authors: Kliche G. , Köhler J. , Bauhofer W. 
Published: March 2015

Silvery reflecting melting cakes of PdS1-xSex (0.0 ≤ x ≤ 1.0) have been prepared by annealing mixtures of Pd, S and Se at 873 K in evacuated quartz tubes. The PdS-type mixed crystals are stable only in the ranges 0.0 ≤ .x ≤ 0.2 and 0.9 ≤ x ≤ 1.0, whereas a new phase appears in the intermediate region. The new phase PdS1-xSex (0.2 < x < 0.9) crystallizes in the space group P42/mbc and Z = 24. Lattice constants are a = 1126.2(7), c = 683.2(7) pm (PdS0.6Se0.4) and a = 1130.8(9), c = 685.4(8) pm (PdS0.4Se0.6). The relationships between the new structure type and the PtS and PdS structure types are discussed.
The infrared reflection spectra of polycrystalline samples of PdS were measured between 10 and 300 K in the frequency range from 30 to 400 cm-1. Both phonons and plasmons contribute to the spectra. The temperature dependence of the plasmon contribution shows an unusual behaviour which is explained by the assumption of a phonon assisted hopping conductivity mechanism at low temperatures and a Drude-like transport at high temperatures. The normal mode which may be involved in the hopping process is proposed from a normal coordinate calculation using a three-parameter short range valence force field model. The electrical transport data are in general agreement with the optical ones. The infrared spectra of the mixed crystals PdS1-xSex (0.2 < x ≤ 1) are discussed.
Hexafluoraceton als Schutzgruppen-und Aktivierungsreagenz in der Aminosäure-und Peptidchemie. Synthese Phosphor-substituierter Sarkosin-Derivate unter Verwendung eines neuen elektrophilen Sarkosin-Synthese-Äquivalents / Application of Hexafluoroacetone as Protecting and Activating Reagent in Amino Acid and Peptide Chemistry. Synthesis of Phosphorus Containing Sarcosine Derivatives via a New Electrophilic Sarcosine Synthone
Authors: Burger Klaus , Heistracher Elisabeth , Simmerl Reinhold , Eggersdorfer Manfred 
Published: March 2015

Abstract
Phosphono-, phosphino-, and phosphinyl-sarcosine derivatives are obtained from 4-bromo-3-methyl-2,2-bis(trifluoromethyl)-1.3-oxazolidin-5-one (8) via M ichaelis-Arbusov reaction.
Zn4FeII
5(PO4)6 ∙ 4H2O : Eine reduzierte und „aufgefüllte“ Variante der Zn2(Zn1-xFex)FeIII(PO4)3 • 2H2O-Struktur / Zn4FeII
5(PO4)6 ∙ 4H2O : A Reduced and „Filled“ Variant of the Zn2(Zn1-xFex)FeIII(PO4)3 • 2H2O Structure
Authors: Schmidt Roswitha , Kniep Rüdiger 
Published: March 2015

Abstract
Single crystals of Zn4FeII
5(PO4)6 ∙ 4H2O were grown by hydrothermal treatment of phosphophyllite (Zn2Fe(PO4)2 ∙ 4H2O) in H2O at 180 °C. The crystal structure (tricl., P1̄; a = 651.6(4) pm, b = 902.7(4) pm, c = 995.4(4) pm, α = 69.01(5)°, β = 78.19(5)°, γ = 75.33(5)°; Z = 1) can be derived from the Zn2(Zn1-xFex)FeIII(PO4)3 ∙ 2H2O structure by reduction of FeIII to FeII and by filling a "structure hole" with an additional FeII.
Strukturen von Tetramesityldistiban (Mes4Sb2) und Trimesitylstiban (Mes3Sb)/Structures of Tetramesityldistibane (Mes4Sb2) and Trimesitylstibane (Mes3Sb)
Authors: Ateș Mustafa , Breunig Hans Joachim , Ebert Klaus H. , Kaller Rose , Dräger Martin , Behrens Ulrich 
Published: March 2015

Abstract
The crystal structure of tetramesityldistibane consists of isolated Mes4Sb2 molecules in the trans conformation (average distance Sb -C 219 pm, distance Sb -Sb 284.9(1) pm, angles SbC2 97°-100°, Sb2C 92°-109°). In the structure of trimesitylstibane there are stacks of isolated trigonal pyramidal Mes3Sb molecules (average distance Sb -C 218 pm, angles SbC2, 104 -106°).
Elektronentransfer und Ionenpaar-Bildung, 28. ESR/ENDOR-Untersuchungen an Radikalanionen und Kontakt-Ionenpaaren der Naturstoff-Chinone Mitomycin C, Streptonigrin, Entobex® und 10,11-Dioxobrucin/Electron Transfer and Ion Pairing, 28. ESR/ENDOR Studies of Radical Anions and Contact Ion Pairs of the Naturally Occurring Quinones Mitomycine C, Streptonigrine, Entobex® and 10,11-Dioxobrucine
Authors: Bock H. , Hänel P. , Herrmann H.-F. 
Published: March 2015

Abstract
Reduction of naturally occurring para-and ortho-benzoquinone derivatives M to their respective radical anions M·⊖ can be accomplished under largely aprotic conditions either by cautious low-temperature reaction in THF containing an excess of (2.2.2) cryptand at a potassium mirror or by using the "mild" single electron transfer reagent tetrabutylammonium boranate R4N⊕BH4
⊖ in DMF. On addition of soluble alkali tetraphenylborates Me⊕[B(C6H5)4]⊖ , their hitherto unknown radical ion pairs [M·⊖ Me⊕]· and/or triple ion radical cations [Me⊕M·⊖Me⊕]·⊕ form, which might be of biological relevance in molecular carrier and "turn off -turn on" switch processes. On addition of metal perchlorates Me⊕n(ClO4
⊖)n with multiply charged counter cations Me⊕n the respective paramagnetic species [M·⊖Me⊕n]·(n-1)⊕ result. Assuming exclusive one-electron transfer reductions without any redox fragmentation reac­tions, ESR, ENDOR and GENERAL TRIPLE spectra are presented and discussed for the following radical anions and radical ion pairs: mitomycin C (M·⊖ and [M·⊖Mex
⊕]·(x-1)⊕ with Me⊕ = Li⊕, Na⊕), streptonigrine (M·⊖ and [M·⊖Lix
⊕]·(x-1)⊕), Entobex® (M·⊖ and [M·⊖Me⊕n]·(n-1)⊕ with Me⊕n = Li⊕, Na⊕, Cd⊕⊕, (H5C6)2Tl⊕) as well as brucinequinone ([M·⊖ Me⊕n]·(n-1)⊕ with Me⊕n = Li⊕, Cd⊕⊕, Pb⊕⊕, La⊕⊕⊕).
Darstellung und Kristallstruktur von Rubidiumdicyanoargentat (I), Rb[Ag(CN)2] · 0,4H2O / Synthesis Crystal Structure of Rubidium Dicyanoargentate (I), Rb[Ag(CN)2] · 0,4H2O
Authors: Kühnei Sabine , Range Klaus-Jürgen 
Published: March 2015

Abstract
Rb[Ag(CN)2] · 0,4H2O was synthesized by reaction of silver cyanide with RbOH and liquid HCN at 0 °C. The colourless crystals are orthorhombic, space group Cmc21, with a = 14.440(3), b = 17.645(1), c = 14.799(1) Å and Z = 32. The structure was solved by Patterson and standard direct methods and refined to R = 0.060 and Rw = 0.051, respectively, for 2204 absorption-corrected unique reflections with F > σ(F). The structure comprises slightly buckled layers of linear [Ag(CN)2]- groups, in which silver atoms are arranged in three- and eight-membered rings. The shortest Ag -Ag distance is 3.05 Å. The rubidium ions are arranged in trigonal-prismatic, cubic and square-antiprismatic sites. Additional cavities contain the water molecules.
Binuclear Fulvalene and Bis(cyclopentadienyl)methane Halfsandwich Complexes of Manganese and Rhenium Containing Tetrahydrothiophene Ligands. X-Ray Structure Analysis of {(CO)2Mn[C5H4-C5H4]Mn(CO)2}(μ-SC4H8)
Authors: Herberhold Max , Biersack Martin , Bitterwolf Thomas E. , Rheingold Arnold L. 
Published: March 2015

Abstract
The photo-induced substitution of carbonyl ligands in the binuclear cyclopentadienyl-type complexes (CO)3M[C5H4(CH2)nC5H4]M(CO)3 (n = 0 (fulvalene), M = Mn (1) and Re (2); n = 1 (bis(cyclopentadienyl)methane), M = Mn (3) and Re (4)) has been studied in the presence of tetrahydrothiophene, SC4H8 (tht). Photodecarbonylation of 1 - 4 in tetrahydrofuran solution leads to solvent-stabilized intermediates which react with tht in the dark to give monosubstituted derivatives (CO)3M[C5H4(CH2)nC5H4]M(CO)2(tht) (1a - 4a). In the case of M = Mn, thtbridged compounds {(CO)2Mn[C5H4(CH2)nC5H4]Mn(CO)2}(μ-tht) (n = 0 (1b) and n = 1 (3b)) are also obtained which are the exclusive products of the photolysis of 1 and 3 in benzene in the presence of tht. Photodecarbonylation of 1 - 4 in neat tetrahydrothiophene produces disubstituted derivatives in the case of manganese, (tht)(CO)2Mn[C5H4(CH2)nC5H4]Mn(CO)2(tht) (n = 0 (1c) and n = 1 (3c)), whereas only the monosubstituted complexes 2a and 4a could be isolated in the case of rhenium. The molecular structure of the tht-bridged fulvalene complex 1b has been determined by an X-ray structure analysis. A special reaction of dimethyl disulfane with the photolyzed tetrahydrofuran solution of 2 leads to the bis(methylthiolato) compound (CO)3Re[C5H4- C5H4]Re(CO)(SMe)2 (5). The new complexes were characterized by their IR spectra v(CO) and their 1H and 13C NMR spectra.
Synthese, Flüssigkristallinität und Photochemie von Di- und Tristyrylbenzolen mit Alkoxyseitenketten / Synthesis, Liquid Crystals and Photochemistry of Di- and Tristyrylbenzenes with Alkoxy Side Chains
Authors: Zerban Georg , Meier Herbert 
Published: March 2015

Abstract
The all-(E)-configurated distyrylbenzenes 4a - g and 1,3,5-tristyrylbenzenes 6a,b,g were prepared by stereoselective condensation reactions of azomethines 2 and methylarenes 3 and 4, respectively. 4a,b,d and e generate light sensitive liquid crystals due to the incorporation of calamitic stilbenoid mesogens (chromophores). The photochemistry leading to the degradation of the LC phases and the photochemistry in solution were investigated with regard to (reversible) E/Z isomerization, cyclodimerization and polymerization. For a comparison {E,Z)-4e was prepared in a multistep sequence and photolyzed.
A New Antibiotic Chloro-Sesquiterpene from the Caribbean Sponge Smenospongia aurea
Authors: Aiello Anna , Fattorusso Ernesto , Menna Marialuisa 
Published: March 2015

Abstract
A new sesquiterpene phenol, containing the rather uncommon chlorine atom, was isolated from a sample of Smenospongia aurea collected along Bahama’s Islands. Its structure has been elucidated by spectroscopic analysis and confirmed via synthesis. This com pound exhibited antibacterial activity.
Intramolekulare Cycloadditionen mit Isobenzofuranen, IX. Synthese eines Pyrano[3,2-c]carbazols / Intramolecular Cycloadditions with Isobenzofurans, IX. Synthesis of a Pyrano[3,2-c]carbazol
Authors: Nagel Jörg , Friedrichsen Willy , Debaerdemaeker Tony 
Published: March 2015

Abstract
Metal catalyzed nitrogen extrusion from the diazo com pound 4b yields a furoindole (5) which can be trapped either by N-phenylmaleinimide or by dimethylacetylendicarboxylate to give 6 and 9, resp. An intramolecular Diels-Alder reaction with 13 b as starting material yields a pyrano[3,2-c]carbazole (14). Q uantum chemical calculations (AM 1, PM 3) on 1, 2, 3, 7a, 9 and 15 are reported.
Strukturverfeinerung von Rubidiumperrhenat bei 297 und 159 K / Structure Refinement of Rubidium Perrhenate at 297 and 159 K
Authors: Rögner Peter , Range Klaus-Jürgen 
Published: March 2015

Abstract
The scheelite-type structure of rubidium perrhenate, RbReO4, has been confirmed and refined from single-crystal X-ray data at two tempera­tures. The compound crystallizes tetragonally, space group I41/a,with a = 5,8401(5), c = 13,265(2) Å at 297(1) K, and a = 5,8289(7), c = 13,109(2) Å at 159(3) K, respectively. Except for a significant decrease in the anisotropic displace­ment factors, the changes in the structural para­meters at low temperature are rather small.
YbMgSn und Eu3Mg4Sn4, erste ternäre Verbindungen in den Dreistoffsystemen Seltene Erden-Magnesium-Zinn / YbMgSn and Eu3Mg4Sn4, First Ternary Compounds in the Systems Rare Earths-Magnesium-Tin
Authors: Allescher-Last H. , Schuster H.-U. 
Published: March 2015

Abstract
Two new ternary compounds YbMgSn and Eu?Mg4Sn4 have been prepared and characterized by X-ray diffraction. YbMgSn crystallizes in the Fe-,P-type structure, space group P-62m. The compound Eu3Mg4Sn4 crystallizes orthorhom bically in the space group Immm. It is isotypic to Li4Sr3Sb4. The structures were calculated from single crystal data.
Synthesis, single-crystal structure determination and Raman spectrum of Cu[C(CN)3]2·2 NH3
Authors: Reckeweg Olaf , Schulz Armin , DiSalvo Francis J. 
Published: March 2015

Abstract
Transparent, light blue crystals of Cu[C(CN)3]2·2 NH3 were obtained by dissolving Cu[C(CN)3]2 in aqueous ammonia and subsequent evaporation of the solvent under ambient conditions. Cu[C(CN)3]2·2 NH3 crystallizes in the space group C2/c (no. 15, Z = 4) with the cell parameters a = 1291.9(3), b = 753.18(15) and c = 1200.8(2) pm, and β = 92.68(3)°. The nature of the tricyanomethanide anion and the ammonia molecules were verified by Raman spectroscopy. Single crystals of Ag[C(CN)3] and Cu[C(CN)3]2 were synthesized, the known structures were confirmed and their Raman spectra were recorded for the first time for comparison.
mer-Triammine trifluorido vanadium(III), mer-[VF3(NH3)3]: synthesis and crystal structure
Authors: Woidy Patrick , Kraus Florian 
Published: March 2015

Abstract
Vanandium trifluoride reacts with dry liquid ammonia under the formation of lilac plate-shaped crystals of mer-triammine trifluorido vanadium(III) (1), mer-[VF3(NH3)3]. Single-crystal X-ray analysis was carried out at low temperature to elucidate the structure. The compound crystallizes in the monoclinic space group P21/c with a = 5.7284(4), b = 9.2033(5), c = 10.5271(6) Å, β = 91.795(6)°, and V = 554.72(6) Å3 at 123 K with Z = 4. The discrete [VF3(NH3)3] molecules are interconnected by hydrogen bonds.
Effect of the Precessing Vortex Core on Primary Atomization
Authors: Bärow Enrico , Gepperth Sebastian , Koch Rainer , Bauer Hans-Jörg 
Published: March 2015

Abstract
The present work is focused on the airblast atomization in a gas
turbine model combustor. Swirl flows in such combustion chambers form
an inner recirculation zone that can develop a precessing vortex
core. This instability affects the velocity field at the exit of the
nozzle, where the fuel is atomized. The influence of the precessing
vortex core on the airblast atomization is examined in this work. The
flow field in the combustion chamber is examined under reacting and
non-reacting conditions. The velocity amplitudes under reacting
conditions are more than twice as high compared to non-reacting
conditions. The influence of the precessing vortex core on the
airblast atomization process is examined in detail at an atomization
test rig with a perspex nozzle. High speed shadowgraphy and POD
analysis have been performed of the liquid film on the prefilmer as
well as on the ligaments formed at the atomizing edge. It was observed
that although the PVC does affect the liquid film flow of the
prefilming surface, it does not affect the breakup into ligaments,
i. e. primary atomization.
La economía informal y el desempleo: el caso de la ciudad de Bucaramanga (Colombia)
Authors: Rodríguez Lozano Gloria Isabel , Calderón Díaz Mayda Alejandra 
Published: March 2015

Se entiende por economía informal o economías subterráneas un conjunto de actividades que están catalogadas en el sector informal de la economía. La informalidad es un fenómeno que se ha presentado en la economía de los países desarrollados y en vía de desarrollo desde décadas atrás, pero a partir de los años setenta, dadas las necesidades de los gobiernos y de organizaciones internacionales, se han realizado numerosos estudios acerca de las economías informales. Estos han sido realizados por la Organización Internacional del Trabajo (OIT) y por diversos autores que han proporcionado un sinnúmero de investigaciones, que han permitido entrever la importancia de la informalidad en las economías del mundo, en vista de que existen excedentes de mano de obra y pocos puestos de trabajo, lo que genera desempleo que, a su vez, conlleva la existencia de la informalidad.Esta investigación tiene como objetivo analizar la economía informal y el desempleo en la ciudad de Bucaramanga, como muestra del excedente de la mano de obra santandereana que no puede ser absorbida en su totalidad por la economía local, generando la existencia de economías informales, mal llamadas "independientes", que no solo no pagan impuestos o no están registradas en la Cámara de Comercio de Bucaramanga sino que, de igual forma, son generadoras de empleos informales y de ingresos.