bluuebunny/crossref_metadata_2025 huggingface dataset:
Predicting Variations in Math Performancein Four Countries Using TIMSS
Authors: Koretz Daniel , McCaffrey Daniel , Sullivan Thomas
Published: March 2015

Although international comparisons of average student performance are a staple of U.S. educational debate, little attention has been paid to cross-national differences in the variability of performance. It is often assumed that the performance of U.S. students is unusually variable or that the distribution of U.S. scores is left-skewed – that is, that it has an unusually long ‘tail' of low-scoring students – but data from international studies are rarely brought to bear on these questions. This study used data from the Third International Mathematics and Science Study (TIMSS) to compare the variability of performance in the U.S., Australia, France, Germany, Hong Kong, Korea, and Japan; investigate how this performance variation is distributed within and between classrooms; and explore how well background variables predict performance at both levels. TIMSS shows that the U.S. is not anomalous in terms of the amount, distribution, or prediction of performance variation. Nonetheless, some striking differences appear between countries that are potentially important for both research and policy. In the U.S., Germany, Hong Kong, and Australia, between 42 and 47 percent of score variance was between classrooms. At the other extreme, Japan and Korea both had less than 10 percent of score variance between classrooms. Two-level models (student and classroom) were used to explore the prediction of performance by social background variables in four of these countries (the U.S., Hong Kong, France, and Korea). The final models included only a few variables; TIMSS lacked some important background variables, such as income, and other variables were dropped either because of problems revealed by exploratory data analysis or because of a lack of significance in the models. In all four countries, these sparse models predicted most of the between-classroom score variance (from 59 to 94 percent) but very little of the within-classroom variance. Korea was the only country in which the models predicted more than 5 percent of the within-classroom variance in scores. In the U.S. and Hong Kong, the models predicted about one-third of the total score variance, and almost all of this prediction was attributable to between-classroom differences in background variables. In Korea, only 19 percent of total score variance was predicted by the model, and most of this most of this was attributable to within-classroom variables. Thus, in some instances, countries differ more in terms of the structure and prediction of performance variance than in the simple amount of variance. TIMSS does not provide a clear explanation of these differences, but this paper suggests hypotheses that warrant further investigation.
Professional Formation in Spain and Germany
Authors: Martínez Usarralde Maria Jesús
Published: March 2015

This article analyzes how the patterns of cooperation among different institutions ensure quality professional preparation in terms of the production of an effective and regulated distribution of competencies. For this analysis we apply the comparative methodology of García Garrido to the Spanish and German models of professional development; and we review educational issues related to the administration, management, and supervision of the professional preparation system in the two countries both at the central and regional levels.
Profile of Chief Academic Officers
Authors: Cejda Brent D. , Rewey Kirsten L.
Published: March 2015

Chief Academic Officer (CAO) is the most common position title before assuming the presidency of a college or university. Results from a national survey are used to develop a profile of the CAO in each respective Carnegie institutional classification. The typical CAO in four-year institutions is Caucasian, male, 54 years old, and married. He holds a doctoral degree, most likely in humanities or social sciences, and has held the CAO position for 5 or fewer years. Most often, the CAO served as a Dean or Associate Dean in the previous position. All CAOs have classroom experience, but 3% have never taught full-time. With only slight variances among the percentages, these characteristics are similar for each of the respective Carnegie classifications. Comparisons are also made between the characteristics of presidents and CAOs.
The Accountability Bind
Authors: Bulkley Katrina
Published: March 2015

Charter schools involve a trading of autonomy for accountability. This accountability comes through two forces—markets through the choices of parents and students, and accountability to government through the writing of contracts that must be renewed for schools to continue to operate. Charter schools are supposed to be more accountable for educational performance than traditional public schools because authorizers have the ability to revoke charter contracts. Here, I focus on one central component of accountability to government: performance accountability or accountability for educational outcomes to charter school authorizers through the revocation or non-renewal of charter contracts. In this paper, I suggest that contract-based accountability for educational performance in charter schools may not be working as proponents argued it would. This article explores some explanations for why there are very few examples of charter schools that have been closed primarily because of failure to demonstrate educational performance or improvement. Future work will need to test if these challenges for authorizers hold in a variety of contexts. The conclusion examines the implications of these findings for the future of charter school accountability.
Analyzing the New York Global History and Geography Exam
Authors: Grant S. G.
Published: March 2015

Education Week's report "Quality Counts" judges New York State's curriculum and assessment policy efforts to be an "A." Surface-level reviews such as "Quality Counts" tell something about the workings of state policy, but they are more useful as snapshots than as well-developed portraits of curriculum and assessment change. In this article, I analyze the new New York State Global History and Geography standards and tests using a set of social studies-specific criteria which inquire deeply into the implications for real instructional change. From that vantage, I argue that New York's policy efforts, while seemingly well-intentioned and reflective of surface-level change, fail to promote powerful teaching and learning in social studies. Teachers intent on producing ambitious teaching and learning will find little to interfere with their efforts. But as a set of reforms intended to encourage substantive change, the new global history test falls short.
Factors Influencing Dropouts' GED & Diploma Attainment
Authors: Wayman Jeffrey C.
Published: March 2015

This study examined correlates of degree attainment in high school dropouts. Participants were high school dropouts of Mexican American or non-Latino white descent who had no degree, a high school degree, or a GED certificate. This study was unique in that it accounted for sample bias of missing data through the use of multiple imputation, it considered students who had dropped out as early as 7th grade, and it was able to include variables found significant in previous research on returning dropouts. Logistic regression analyses identified a parsimonious set of factors which distinguished dropouts who held degrees (diploma or GED) from those who did not. Similar analyses were performed to distinguish participants who had attained diplomas from those who had attained GEDs. It was estimated that 59.2% of dropouts return to obtain high school credentials. School capability, age at dropout, and socio-economic status significantly predicted degree attainment. Presence of children, higher school capability and socio-economic status were associated with GED attainment, while later grade at dropout was associated with diploma attainment. These relationships did not vary by ethnicity, although degree attainment was less likely for Mexican American dropouts. The study concludes that dropping out is not the end of a student's education, and more research should be directed toward returning dropouts. Further, the focus of such research should be expanded to include a more positive and broader range of correlates.
Local Flexibility within an Accountability System
Authors: Scafidi Benjamin , Freeman Catherine , DeJarnett Stan
Published: March 2015

Over the past decade, several states have created comprehensive accountability systems designed to increase student learning in public schools. These accountability systems are based on "high-stakes" standardized testing of a state curriculum. Rewards and interventions for local educators are based largely upon students' performance on these tests. Using the recent accountability reforms in Georgia as a backdrop, this article considers the role of local flexibility within such an accountability system--flexibility over paperwork, resources, personnel, and curriculum for local educators. Increased flexibility for local educators is not merely an option in a world where local educators are subject to a comprehensive accountability system imposed by a state--it is a requirement for success. We make a case for providing local flexibility and provides a discussion regarding types of flexibility, vehicles for granting flexibility, and who should receive flexibility.
Does the Degree of Campus "Wiredness" Matter?
Authors: Hu Shouping , Kuh George D.
Published: March 2015

Responses to the College Student Experience Questionnaire 4th Edition from 18,844 students at 71 colleges and universities were analyzed to determine if the presence of computing and information technology influenced the frequency of use of various forms of technology and other educational resources and the exposure to good educational practices. Undergraduates attending "more wired" campuses as determined by the 1998 and 1999 Yahoo! Most Wired Campus survey more frequently used computing and information technology and reported higher levels of engagement in good educational practices than their counterparts at less wired institutions. Non-traditional students benefited less than traditional students, but both women and men students benefited comparably from campus "wiredness."
Gender Barriers in Higher Education: The Case of Taiwan
Authors: Wang Ru-jer
Published: March 2015

As a consequence of the rapid expansion of higher education in Taiwan over the past decades, the enrolment of females in higher education has grown considerably. However, this article reports that in terms of institutional difference, access to advanced study, and differing subject preferences, the barriers to women's participation in higher education remain. Thus, the findings drawn from this article lead to the conclusion that females still suffer disadvantages in access to higher education, although the expansion of higher education in Taiwan has substantially benefited females over the past few decades.
Synthesis and characterization of functionalized 4-O-methylglucuronoxylan derivatives
Authors: Chemin Maud , Rakotovelo Alex , Ham-Pichavant Frédérique , Chollet Guillaume , da Silva Perez Denilson , Petit-Conil Michel , Cramail Henri , Grelier Stéphane
Published: March 2015

The purpose of this study was to design new biomaterials based on functionalized xylan derivatives. In one approach, 4-O-methylglucuronoxylan (MGX) of beechwood was oxidized by sodium periodate (NaIO4). A ratio of 0.2 NaIO4/xylose leads to a degree of oxidation of 0.15 with 75% yield. Then, the oxidized MGX aldehyde was submitted to reductive amination reaction with benzylamine, and as a result, the xylan backbone was effectively grafted with benzyl groups with a degree of substitution of 0.11. In another approach, controlled sulfuric acidic hydrolysis of MGX was performed to get well-defined xylooligosaccharides (XOS). Then, the reductive amination reaction of the XOS aldehyde functions was performed with allylamine or 2-aminoethylazide to graft the chain ends with an allyl or an azide function, respectively. The proposed methods can open a route to the design of new functional biomaterials.
Interrelationship between lignin-rich dichloromethane extracts of hot water-treated wood fibers and high-density polyethylene (HDPE) in wood plastic composite (WPC) production
Authors: Pelaez-Samaniego Manuel R. , Yadama Vikram , Garcia-Perez Manuel , Lowell Eini , Zhu Rui , Englund Karl
Published: March 2015

Hot water extraction (HWE) partially removes hemicelluloses from wood while leaving the majority of the lignin and cellulose; however, the lignin partially migrates to the inner surfaces of the cell wall where it can be deposited as a layer that is sometimes visible as droplets. This lignin-rich material was isolated via Soxhlet extraction with dichloromethane to investigate its rheological behavior in blends with high-density polyethylene (HDPE), a common material in wood plastic composites (WPCs). Pyrolysis gas-chromatography/mass spectrometry (Py-GC/MS) and electrospray ion mass spectrometry (ESI/MS) confirmed that the isolated material is constituted mainly of low-molecular-weight lignin oligomers. The blends of HDPE/isolated lignin, in varying ratios, were tested by means of dynamic rheology. A “shoulder” was found in plots “shear storage moduli (G′) vs. frequency sweep” and a shift of the terminal zone to lower frequencies was observed. Apparently, this shoulder is caused by the elastic contribution of the interfacial tension between the blend components. The rheology of WPCs produced from HWE wood and HDPE shows a similar shoulder in G′ plots, suggesting that the HDPE/lignin blends are in part responsible for the shape of the G′ curves.
Common burdock (Arctium minus): a common weed of nonarable land in Orestiada, Greece
Authors: Damalas C.A. , Alexoudis C. , Koutroubas S.D.
Published: March 2015

Common burdock (Arctium minus) is a common biennial weed of non-arable land in typical rural settings of Orestiada, Greece. The aim of this study was to describe the basic morphological traits of this species throughout the main phenological stages of its life cycle and to obtain some insight into its growth and productivity in Orestiada. Based on our observations, the plants occurred most commonly in moist and fertile soils, usually as isolated individuals or in small patches near the parent plants. The species is characterized by its large basal ‘elephant-ear’ leaves during the vegetative stage, appearing in alternate arrangement, with irregularly wavy and non-toothed edges, as well as with long hollow stalks forming a noticeable furrow on the top. By monitoring individual plants, it was found that fl owering (in the second year of growth) mostly occurred from late June up to early August. The fl owers were purple, occurring in bristly heads at the top of the stem. The bristly heads formed a fruit, containing small black seeds. The average number of capitula per plant, from randomly selected populations in Orestiada, was found to be 69.7 and 57.7 respectively, whereas the mean seed number per capitulum reached 30.3 and 33.3 seeds, respectively
Optimization of Microwave Roasting for Dechlorination of CuCl Residue under Oxygen-Enriched Condition
Authors: Zhanyong Guo , Shaohua Ju , Jinhui Peng , Libo Zhang , Ting Lei
Published: March 2015

The clean utilization of the residue containing chloride, such as zinc oxide dust and CuCl residue, produced from zinc hydrometallurgy is very important for the recycle of valuable metals. In this paper, a new technology for dechlorination of the CuCl residue through thermal treatment with application of microwave and oxygen-enriched air roasting is brought out. And the response surface methodology (RSM) based on five-level, three-variable and central composite design (CCD) was used to optimize the operation parameters for increasing the dechlorination efficiency. The effects of temperature, roasting time and oxygen consumption on the dechlorination efficiency were studied and the optimal process conditions were identified. In addition, X-ray diffraction (XRD), scanning electron microscope (SEM) and Raman spectroscopy were used to characterize the dechlorination process under the optimum condition. The results showed that the experimental data were fitted to a second-order polynomial equation. The optimized process conditions are identified to be a roasting temperature of 451℃, heating duration of 114 min and oxygen consumption of 2.4 times the theoretical oxygen demand. A dechlorination efficiency of 96.4% could be achieved at the optimal process conditions.
Nerve growth factor-induced myoprotection in C2C12 muscle cells is mediated by α9β1 integrin via release of PGE2
Authors: Ettinger Keren , Nevo Yoram , Marcinkiewicz Cezary , Lazarovici Philip
Published: March 2015

Background: Nerve growth factor (NGF) mediates a wide range of activities in the central nervous system including neuronal differentiation, synaptic plasticity, and neuroprotection. In addition, NGF places an important role in skeletal muscle physiology by some unknown mechanisms. We recently demonstrated that NGF conferred myoprotection toward ischemia in C2C12 skeletal muscle cell model, establishing an important trophic role for NGF in skeletal muscle.

Methods: In this report, using ELISA and oxygen-glucose deprivation (OGD) assays, we investigated the potential contribution of prostaglandin E2 (PGE2) to NGF myoprotective effects toward C2C12 cultures exposed to OGD insults. Vipera lebetina obtusa disintegrin 5 (VLO5), a selective antagonist of α9β1 integrin, was used as an experimental tool to clarify α9β1 integrin role in NGF action.

Results: NGF-induced mitogen-activated protein kinase type 1 or 2 (ERK1/2) phosphorylation in C2C12 cells and in a dose-response fashion stimulated PGE2 release, both effects antagonized by VLO5 and PD98059. NGF-induced myoprotection of the cells exposed for 7 h to OGD, followed by 18 h of reoxygenation, was reversed by VLO5 treatment.

Conclusions: These results suggest that NGF activation of α9β1 integrin induced myoprotection by stimulation of ERK phosphorylation and release of cytoprotective PGE2 mediator. This effect may be also relevant for NGF-induced pain and hyperalgesia in the skeletal muscle.
Flow Visualization by Means of Contactless Inductive Flow Tomography in the Presence of a Magnetic Brake
Authors: Ratajczak Matthias , Wondrak Thomas , Timmel Klaus , Stefani Frank , Eckert Sven
Published: March 2015

In continuous casting DC magnetic fields perpendicular to the wide faces of the mold are used to control the flow in the mold. Especially in this case, even a rough knowledge of the flow structure in the mold would be highly desirable. The contactless inductive flow tomography (CIFT) allows to reconstruct the dominating two-dimensional flow structure in a slab casting mold by applying one external magnetic field and by measuring the flow-induced magnetic fields outside the mold. For a physical model of a mold with a cross section of 140 mm×35 mm we present preliminary measurements of the flow field in the mold in the presence of a magnetic brake. In addition, we show first reconstructions of the flow field in a mold with the cross section of 400 mm×100 mm demonstrating the upward scalability of CIFT.
Idiopathic short stature due to novel heterozygous mutation of the aggrecan gene
Authors: Quintos Jose Bernardo , Guo Michael H. , Dauber Andrew
Published: March 2015

Recently, whole exome sequencing identified heterozygous defects in the aggrecan (

We report a novel frameshift mutation in

We present a 5 1/2-year-old male with a family history of short stature in three generations. The maternal grandfather stands 144.5 cm (Ht SDS –4.7), mother 147.7 cm (Ht SDS –2.6), and index case 99.2 cm (Ht SDS –2.7). Our prepubertal patient has significant bone age advancement (bone age 8 years at chronologic age 5 1/2 years) resulting in a poor predicted adult height of 142 cm (Ht SDS –5.1). DNA sequencing identified a novel heterozygous variant in

Mutations in the
Zum thermischen Verhalten einiger Kohlensäure[(methylphenylsilyl)methyl]ester-Derivate
Authors: Tacke Reinhold , Link Matthias , Bentlage-Felten Anke , Zilch Harald
Published: March 2015

The synthesis and the thermal behaviour of the (methylphenylsilyl)methyl carbonates CH3(C6H5)Si(H)CH2OC(O)X (6: X = OCH3; 7: X = Cl; 8: X = N(CH3)2) is described. 8 rearranges in toluene solution at 100 °C quantitatively to give the carbam oyloxysilane C6H5(CH3)2SiOC(O)N(CH3)2 (11), whereas neat 6 and 7 at 135 °C undergo quantitative formation of C6H 5(CH3)2SiOCH3 (12) and C6H5(CH3)2SiCl (13), respectively. The formation of 12 and 13 is explained by a rearrangement reaction (by analogy to the rearrangement of 8), follow ed by a decarboxylation. The thermally induced transformations 6 →12, 7 →13, and 8 →11 were found to be first-order reactions with half-lifes of ~2.6 h (135 °C, neat), ~4.5 h (135 °C, neat), and ~3.7 h (100 °C, in toluene), respectively.
Chemie polyfunktioneller Moleküle, 90 [1] Antimon-, sauerstoff-, schwefel- und selenhaltige Käfigverbindungen mit Adamantan-, Noradamantan- und Nortricyclan-Struktur
Authors: Ellermann Jochen , Veit Adolf
Published: March 2015

Reactions of 1,1,1-tris(dichlorostibinomethyl)ethane, CH3C(CH2SbCl2)3 (1), with water afford, depending on the molar ratios of the components, the adamantane structured CH3C (CH2SbO)3 (2) or Sb4O6, whereas with H2S only the heteroadamantane CH3C(CH2SbS)3 (3) is obtained. With NaSeH com pound 1 forms CH3C(CH2SbSe)3 (4) accompanied by the heteronoradamantane CH3C(CH2Sb)3Se2 (5). Several attempts to prepare an antimony and tellurium containing adamantane or noradamantane failed, as 1 was reduced by Na2Te yielding the heteronortricyclane CH3C(CH2Sb)3 (6). Oxidation of the latter in tetrahydrofuran by air gives Sb4O6. The new com pounds have been characterized by mass, infrared, Raman, and as far as possible, by 1H NMR spectroscopy.
Discotische Flüssigkristalle: Beziehung zwischen Molekülstruktur und discogenen Eigenschaften scheibenförmiger Verbindungen, nicht-flüssigkristalline Ester des myo-Inosits und des Mytilits [1,2]
Authors: Kohne Bernd , Praefcke Klaus , Stephan Werner , Nürnberg Peter
Published: March 2015

A modified synthesis of mytilitol and the synthesis of various esters of the cyclitols myo-inositol (la) and mytilitol (2a) is described. Because of steric reasons all these derivatives of the two naturally occuring compounds exhibit no discotic mesophases. For instance, in comparison to mesomorphous scyllitol hexaesters already the methyl group perpendicular to the molecular core in the analogous hexaesters 2b-d of mytilitol suppresses discotic liquid crystalline character totally. This effect is discussed in connection to the relationship of mesomorphism with chemical structure of disc-shaped molecules.
Darstellung von Tetraioddiborylmethan
Authors: Siebert Walter , Ender Ulrich , Schütze Reinhard
Published: March 2015

Reaction between BCl3 and CH2(AlCl2)2 leads to tetrachlordiborylmethane, which reacts with BI3 to give tetraioddiborylmethane in 64% yield.
μ-Nitridokomplexe von Wolfram(VI) Die Kristallstruktur von PPh4[W2NCl10]/ μ-Nitrido Complexes of Tungsten(VI) The Crystal Structure of PPh4[W2NCl10]
Authors: Godemeyer Thomas , Berg Alexander , Groß Hans-Dieter , Müller Ulrich , Dehnicke Kurt
Published: March 2015

W2NCl9 was obtained as a brilliant red crystal powder from tungsten hexachloride and tris(trimethylsilyl)amine. According to its IR spectrum it has dimeric molecules [W2NCl9]2 with bridging chlorine atoms. Its reaction with tetraphenylphosphonium chloride yields PPh4[W2NCl10], and with phosphorus oxide chloride W2NCl9 ·OPCl3 is obtained; both are soluble in dichlorom ethane. The crystal structure of PPh4[W2NCl10] was determined by X-ray diffraction (2521 observed reflexions. R = 0.065). Crystal data: triclinic, space group P1̄, Z = 2, a = 1125.7, b - 1278.2, c = 1347.8 pm, α = 110.08, β = 94.55, γ = 111.55°. The structure consists of PPh4ⓛ ions which are arranged to (PPh4
ⓛ)2 pairs about inversion centres, and of [W2NCl10]⃝ anions. The latter possess an almost linear W NW group (173°) with slightly different WN bond lengths of 179 and 188 pm corresponding to double bonds. Each tungsten atom has an octahedral coordination. The WCl bonds trans to the nitrido ligand are about 9 pm longer than the bonds in the cis positions.
Vom Fluorsilan zum Siloxan — 1,3-Silylgruppenwanderung am Si3CSiO-Gerüst/ From a Fluorosilane to a Siloxane — 1,3-Migration of Silyl Groups in the Si3CSiO System
Authors: Klingebiel Uwe , Pohlmann Sabine , Skoda Lutz , Lensch Cornelia , Sheldrick George M.
Published: March 2015

The nature of the products which are formed in the reaction of tris(trimethylsilyl)Methylfluorosilanes (Me3Si)3C -SiF2R with KOH depends on the bulkiness of the substituents R. The condensed siloxane is obtained for R = F . The crystal structure determination of this siloxane (Me3Si)3C -SiF2-O -SiF2-C (SiMe3)3 shows that the Si -O - Si unit is linear. A fluorosilanol as well as a siloxane could be isolated for R = Me. 1,3-Migration of one or two trimethylsilyl groups from the carbon to the oxygen takes place for R = phenyl, rm-butyl or silylamine, with formation of siloxanes which are isomeres o f the expected silanols.
Untersuchungen am System Triphenylphosphingold(I)/Sulfat: Synthese und Röntgenstrukturanalyse von (Ph3PAu)2SO4 · CH3OH/ Studies of the System Triphenylphosphinegold(I)/Sulphate: Synthesis and Crystal Structure of (Ph3PAu)2SO4 · CH3OH
Authors: Hohbein Rainer , Jones Peter G. , Meyer-Bäse Karen , Schwarzmann Einhard , Sheldrick George M.
Published: March 2015

The reaction between (triphenylphosphine)acetatogold(I) and concentrated sulphuric acid in methanol leads to (Ph3PAu)2SO4 (1) or [(Ph3PAu)3O]+ HSO4
- , depending on the acid concentration. The crystal structure of the methanol solvate of (1) was determined [C2/c, a = 1348.3(2), b = 1451.0(2), c = 1853.8(3) pm, β = 99.90(2)°, Z = 4, R = 0.037 for 3138 unique observed reflections], 1 possesses crystallographic twofold symmetry, with Au -O 206.3, Au -P 221.6 pm. The corresponding selenate is isomorphous.
Besetzungsvarianten der CaMnBi2-Struktur: Zur Kenntnis der Verbindungen LaZn0,52Sb2, LaCo0,68Sb2, LaMnxSb2 (0,65≤x≤ 0,76) und LaCux-Sb2 (0,82≤x≤ 0,87) / New Compounds with the CaMnBi2 Structure: On LaZn0,52Sb2, LaCo0,68Sb2, LaMnxSb2 (0,65≤x≤ 0,76) und LaCux-Sb2 (0,82≤x≤ 0,87)
Authors: Cordier Gerhard , Schäfer Herbert , Woll Petra
Published: March 2015

The new compounds LaZn0,52Sb2, LaCo0,68Sb2, LaMnxSb2 (0.65 ≤ x ≤ 0.76) and LaCuxSb2 (0.82 ≤x≤ 0.87) crystallize in the tetragonal system , space group P4/nmm (N o. 129) with the CaMnBi2 structure. The lattice constants are:

LaZn0,52Sb2: a = 438.0(3) pm, c = 1048.8(5) pm, c/a = 2.395; LaCo0,68Sb2: a = 439.4(3) pm, c = 995.4(5) pm, c/a = 2.265; LaMnxSb2: für x = 0.65: a = 438.7(3) pm, c = 1078.0(5) pm, c/a = 2.457; für x = 0.76: a = 437.2(3) pm, c = 1093.3(5) pm, c/a = 2.501; LaCuxSb2: für x = 0.82: a = 440.2(3) pm, c = 1015.4(5) pm, c/a = 2.307; für x = 0.87; a = 437.3(3) pm, c = 1040.0(5) pm, c/a = 2.378.
Die kristallinen Phasen der Alkalitrimolybdate / The Crystallinic Phases of the Alkali Trimolybdates
Authors: Förster A. , Kreusler H. U. , Fuchs J.
Published: March 2015

The structure of NaRbMO3O10 (1) was investigated. The compound crystallizes in the space group Pnma with the lattice param eters a = 7.589 Å , b = 7.579 Å , c = 15.489 Å.

Its anion chain is identical with that of Rb2MO3O10·H2O (2) but the packing is more close. Contrary to (2), (1) does not change into a monoclinic phase on heating. (2) is changed into the hydrate of (1 ) when treated with a solution of sodium chloride.

The lattice parameters of several alkali trimolybdates were determined from powder patterns.

The stepwise dehydration of the trimolybdate hydrates was studied by X-Ray, spectroscopical and thermoanalytical methods.
Anomale Michaelis-Becker-Reaktion: 1-PhenyIethan-1,2,2-trisphosphonsäure und ihre Ester / Anomalous Michaelis-Becker Reaction: 1-Phenylethan-1,2,2-triphosphonic Acid and their Esters
Authors: Fischer Ulrich , Hägele Gerhard
Published: March 2015

Sodium dialkylphosphite reacts with trichlorovinylbenzene to yield in an one-batch procedure 1-phenyl-1,2,2-ethanetrisphosphonic acid hexaalkyl esters. A carbanionic intermediate of an “anomalous Michaelis-Becker reaction” is deduced. Acidolysis of esters leads to the parent trisphosphonic acids. NMR param eters of this acid are strongly influenced by protolytic equilibrium.
Flüssig-kristalline Verbindungen aus der Thiophenreihe, Teil 2. Flüssig-kristalline Azomethine, Azine und Vinylene / Liquid Crystalline Compounds in the Thiophene Series 2. Liquid Crystalline Azomethines, Azines and Vinylenes
Authors: Koßmehl Gerhard , Budwill Detlev
Published: March 2015

Azomethines, azines, vinylenes and hexatrienes containing thiophene and thieno[3,2-b]- thiophene systems have been synthesized and characterisized by their IR and 1H NMR spectra. The liquid crystalline properties of these compounds have been studied thermically and optically by their textures and are compared with the analogous compounds having benzene rings.
Synthese und Kristallstruktur von Bis[1,5-ditolyIpentaazadienido-silber(I)] und Bis[1,3-diphenyItriazenido-silber(I)] / Synthesis and Crystal Structure of Bis[1,5-ditolylpentaazadienido-silver(I)] and Bis[1,3-diphenyltriazenido-silver(I)]
Authors: Beck Johannes , Strähle Joachim
Published: March 2015

The reaction of 1,5-ditolylpentaazadiene with Ag(NH3)2
+ in concentrated ammonia yields orange-red [Ag(TolNNNNNTol)]2. This compound crystallizes in the monoclinic space group P21/n with the lattice constants a= 525.7, b = 1236.1, c = 2189.6 pm, β = 90.88°. Z = 4. In the centrosymmetric and approximately planar dimers the Ag+ ions are coordinated by the outer N atoms N1 and N5 of the N5 chain forming a twelve-membered Ag2N10 ring. The coordination is almost linear with N1-Ag-N5′ = 160° and Ag-N1 = 218, Ag-N5′ = 216 pm. [Ag(PhNNNPh)]2 was obtained by the reaction of 1,3-diphenyltriazenidc with AgNO3 in THF. It crystallizes from pyridine in yellow, monoclinic needles with the space group C2/c. The lattice constants are a = 2602.3. b = 547.1, c = 1693.4 pm, β = 118.13°. Z = 4. The centrosymmetric complexes are planar and satisfy nearly the symmetry D2h. The N3 chains bridge the Ag ions in an eight-membered ring with N1 - Ag-N3′ = 167° and Ag-N1 = 215, Ag-N3′ = 214 pm. The Ag+ ions exhibit a very short distance of Ag-Ag′ = 266.9 pm that must be interpreted by bonding interactions.
Transition Metal Squarates I. Chain Structures M (C4O4) · 4 H2O
Authors: Weiss Armin , Riegler E. , Alt I. , Böhme H. , Robl Ch.
Published: March 2015

The transition metal squarates M(C4O4) · 4 H2O (M2+ = Mn2+, Fe2+, Co2+. Ni2+, and Zn2+) are isotypic. They crystallize monoclinically, space group Ce-Cf, and consist of one-dimensional chain molecules

[xxx]

with the chain axes alternatively in direction [110] and [110]. The transition metal is octahedrally coordinated by two oxygen atoms of two C4O4
2- -anions in rrarcs-position and 4 water molecules. Neighbouring chains are interlinked by hydrogen bonds. The distance between the planes of the parallel C4-rings of neighbouring chains is similar to the layer distance in graphite.
BaAl4-Strukturvarianten bei ARu2X2(A = Ca, Sr, Ba, Eu; X = P, As) und APt2P2—x (A = Ca, Eu) / BaAl4-Denvative Structures of ARu2X2 (A = Ca, Sr, Ba. Eu; X = P, As) and of APt2P2-x (A = Ca, Eu)
Authors: Wenski Guido , Mewis Albrecht
Published: March 2015

Compounds ARu2P(As)2 (A = Ca, Sr. Ba. Eu) were found to have the ThCr2Si2-type structure (14/mmm). Single crystals of CaRu2P2 (a = 404.6 pm, c = 977.1 pm) and EuRu2P2 (a = 402.9 pm, c = 1077.2 pm) were obtained using tin as a flux. In the case of the Pt compounds, single crystals could be isolated from powder samples. Ca(Eu)Pt2P2-x crystallizes isotypically in a new structure type which can be described as a stacking variation of the CaBe2Ge2-type structure (14/mmm; CaPt2P1.43: a = 409.9 pm, c = 1895.1 pm; EuPt2P1.62: a = 414.3 pm; c = 1912.0 pm). The crystal structures of Ca(Eu)Ru2P2 and Ca(Eu)Pt2P2-x were refined from four-circle diffractometer data. Magnetic susceptibility measurements prove the divalent nature of Eu in all Eu compounds.
Methylaminodiphenylborane — Application of 11B, 13C, 14N, 15N NMR
Authors: Wrackmeyer Bernd
Published: March 2015

11B, 13C, 14N, 15N NMR is used to study methylaminodiphenylborane (1). Compound 1 can be regarded as a model compound for studying BN(pp)π-. BC(pp)π interactions, for determining the barrier to rotation about the B-N bond and for the application of natural abundance 15N NMR to boron-nitrogen chemistry. The 13C NMR of 1 shows a large splitting of the 13C(para) resonances (in contrast to reports on similar compounds in the literature) as a consequence of hindered rotation about the BN bond. The difference in the 13C(para) nuclear shielding indicates different mesomeric interactions between the trigonal boron atom and the two phenyl groups.
Oligophosphan-Liganden, XIV [1] Bis(distickstoff)molybdän-KomplexeMo(N2)2[PhP(CH2CH2CH2PPh2)2](PR3) / Oligophosphine Ligands, XIV [1] Bis(dinitrogen)molybdenum Complexes Mo(N2)2[PhP(CH2CH2CH2PPh2)2](PR3)
Authors: Dahlenburg Lutz , Pietsch Bernd
Published: March 2015

The reaction of MoCl3(THF)3 with PhP(CH2CH2CH2PPh2)2 in THF/CH2Cl2 gave MoCl3(PhP(CH2CH2CH2PPh2)2) ·CH2CI2 (1). Sodium amalgam reduction of I in the presence of the monotertiary phosphines PMe3-nPhn (n = 0, 1, 2), in THF under nitrogen atmosphere, yielded the bis(dinitrogen) complexes

Mo(N2)2[PhP(CH2CH2CH2PPh2)2](PMe3) (2),

Mo(N2)2[PhP(CH2CH2CH2PPh2)2](PMe2Ph) (3), and

Mo(N2)2[PhP(CH2CH2CH2PPh2)2I(PMePh2) (4).

The homologous PPh3 and i-Pr3P derivatives as well as the attempted tris(dinitrogen) species Mo(N2)2[PhP(CH2CH2CH2PPh2)2] could not be isolated. Compounds 2-4 were assigned trans coordination of the N2 ligands on the basis of their IR, Raman, and 31P NMR spectra. The trans- octahedral geometry of these complexes was also confirmed by a single-crystal X-ray diffraction study performed on 3.
Thermal Decomposition of Aromatic Thioureas [1]
Authors: Párkányi Cyril , Al-Salamah Mohammed A.
Published: March 2015

Thermal decomposition of aromatic and heteroaromatic thioureas in boiling chlorobenzene is a first-order reaction. The reaction involves intramolecular hydrogen transfer followed by a cleavage of the C - N bond which is the rate-limiting step. The rate constants of decom position have been determined and correlated with quantum-chemical reactivity indices.
NOTIZEN: Iridiumphosphidtellurid, IrPTe / Iridium Phosphide Telluride, IrPTe
Authors: Kliche Gerhard
Published: March 2015

IrPTe was prepared by annealing stoichiometric mixtures of IrP2 and IrTe2 in evacuated quartz tubes at 1100-1150 °C/2 davs. From the lattice constants (a = 6.030(1), b = 6.131(1), c = 12.132(1) Å) and the infrared absorption spectrum a structure similar to CoSbS (paracostibite) is concluded.
Darstellung und Eigenschaften des Tribrom-cyclo-1λ6-wolfram-3,5-dithia-2,4,6-triazens/Synthesis and Properties of Tribromo-cyclo-1λ6-tungsten-3,5-dithia-2,4,6-triazene
Authors: Roesky Herbert W. , Schimkowiak Jürgen , Noltemeyer Mathias , Sheldrick George M.
Published: March 2015

The metallacycle [Br3WS2N3] has been obtained from the reaction of S4N4 with WBr5. The salt [Ph4P+][Br4WS2N3
-] was formed from [Br3WS2N3] by addition of Ph4PBr. It crystallizes in the orthorhombic space group Pbca with a = 1396.8(4), b = 1961.9(5), c = 2108.0(4) pm, and Z = 8. The following mean bond lengths were observed in the anion: W-N 184.2, W-Br 256.8, N-S 157.8 pm.
Über die Konfigurations- und Substituenten-Abhängigkeit der 1H- und 13C-NMR-Parameter in substituierten Verbindungen vom Typ cis- und trans-Bis(phenyl)bis(tri-n-butylphosphan)platin(II)/The Dependence of 1H and 13C NMR Parameter on Configuration and Substituents in Substituted cis- and trans-Bis(phenyl)bis(tri-n-butylphosphane)platinum (II) Compounds
Authors: Brune Hans Albert , Müller Wolf-Dieter , Spohn Karl-Heinz
Published: March 2015

1H and 13C NMR spectroscopic parameter of in the phenyl rings substituted compounds of the type cis- and trans-bis(phenyl)bis(tri-n-butylphosphane)platinum(II) are reported and discussed with respect to correlations between coupling constants especially with platinum-195 and molecular configuration and substituent effects.
Synthese von Mesitylstibanen / Synthesis of Mesitylstibanes
Authors: Ates M. , Breunig H. J. , Soltani-Neshan A. , Tegeler M.
Published: March 2015

Trimesitylstibane (1) reacts with SbCl3 or SbBr3 to form the halostibanes Mes2SbCl (2), MesSbCl3 (3), Mes2SbBr (4). or MesSbBr2 (5) [Mes = 2,4,6-(CH3)3C6H2]. Action of MesMgCl on an excess of SbCl3 or SbBr3 at low temperatures gives Mes3SbCl2 (6) or Mes3SbBr2 (7), resp. Addi­tion of Br2 to 1 gives 7 in 96% yield. The silylstibanes Mes2SbSiMe3 (8) and McsSb(SiMc3)2 (9) are formed by dehalogenation of Me3SiCl and 4 or 5 by Mg filings in tetrahydrofuran. Mes2SbOSiMe3 (10) is obtained by air oxidation of 8. Reduction of 4 with Mg gives Mes2SbSbMes2 (19). Crystals of the composition (MesSb)6·C6H6 (13a) or (MesSb)4·C6H5CH3 (13b) are obtained from Mg and 5 after work-up in benzene or toluene, resp.
Average Structure of Bis(oxamide oximato)nickel(II) X Dimethyl-tetracyanoquinodimethane, a “Charge Transfer” Compound with Mixed Stacks and Variable Paramagnetism
Authors: Endres Helmut , Bongart August , Nöthe Dietrich
Published: March 2015

The average unit cell of the methanol solvate [Ni(C2H5N4O2)2] × C14H8N4 × 2CH3OH, MΓ = 589.22 is triclinic. Ρ1̄, a = 8.539(3). b = 8.937(3). c = 9.418(3) Å, α = 103.39(3). β = 100.12(2), γ = 105.39(2)°, V = 652.2 Å3 Z = 1, dc = 1.50 gem-3, final Rw = 0.050 for 1580 observed independent reflections. Satellite reflections hint at a modulation of the structure in the ac plane. Mixed stacks of alternating and mainly neutral metal complex and Me2tcnq molecules are formed.

Crystals grown with electrochemical reduction show a weak activated paramagnetism, those grown without electrochemical support are diamagnetic.
Synthesis of New Complexons: N-Hydroxy-α,α′-iminodipropionic-and N-Hydroxyiminodiacetic Acid
Authors: Koch E. , Kneifel H. , Bayer E.
Published: March 2015

Reaction conditions for the synthesis of N-hydroxy-α, α′-iminodipropionic acid, the ligand of naturally occurring amavadin. and N-hydroxyiminodiacetic acid, the first member of this class of complexons, have been investigated.
Structural Studies on Vindolinine
Authors: Atta-ur-Rahman  , Malik Sohail , Albert Klaus
Published: March 2015

19-S-Vindolinine has been found to undergo an interesting isomerisation in chloroform to 19-R-vindolinine at room temperature. NOEDS measurements have been carried out on both isomers and a 13C solid state CP-MAS spectrum recorded for 19-S-vindolininc. The structure assigned as 16-epi-19-S-vindolinine to an alkaloid isolated previously from Catharanthus roseus has been revised in the light of corrected 13C NMR values for 19-S- and 19-R-vindolinine.
Notizen: Die Umylidierungsreaktion von Zirkoniumtetrachlorid mit Phosphonium-yliden: Struktur von Methyl-tris(diethylamino)- phosphonium-Hexachlorozirkonat / The Transylidation Reaction of Zirconium tetrachloride with Phosphonium Ylides: Structure of Methyl-tris(diethylamino)- phosphonium Hexachlorozirconate
Authors: Schmidbaur Hubert , Pichl Reinhard , Muller Gerhard
Published: March 2015

The reaction between ZrCl4 and (Et2N)3P=CH2 affords the zirconium-substituted vlide [(Et2N)3PCZrCl2]2 (1). The transylidation by-pro­duct [(Et2N)3PCH3]Cl is trapped by excess ZrCl4 to give the complex salt [(Et2N)3PCH3]2ZrCl6 (2) the structure of which was determined by single crystal X-ray diffraction.
Beiträge zur Chemie perhalogenierter Thiocarbonyle, Selenocarbonyle und Selendiimine / Advances in Perhalogeno Thiocarbonyl, Selenocarbonyl and Selenodiimine Chemistry
Authors: Fockenberg F. , Haas A.
Published: March 2015

Trifluorom ethylselenylthiocarbonyls form with CF3-nClnSCl or CF3SeCl the corresponding disulfanes or selanesulfanes. Oxidation of CF3SeC(S)X , X = CF3Se, CF3S, Cl, or Br, with 3-Cl - C6H4C(O)OOH yields com pounds CF3Se(X )C = S = O . Only decomposition products are obtained from (CF3Se)2CSe and Cl2, CF3SeCl, CF3SCl, or 3-Cl-C6H4C(O)OOH . The preparation o f com pounds RN = Se = NR , R = (CH3)3Si, CF3C(O), or CF3SO2, is described. Physical and spectroscopical data of the new substances are provided
Bildung von Nitridokomplexen durch Ammonolyse von Metallhalogeniden mit NH4
+. Synthese und Struktur von (NH4)3Nb2NBr10, (NH4)3Ta2NI10 und (NH4)3W2NBr10 / Formation of Nitrido Complexes by Ammonolysis of Metal Halides with NH4
+. Synthesis and Structure of (NH4)3Nb2NBr10, (NH4)3Ta2NI10 and (NH4)3W2NBr10
Authors: Hörner Manfredo , Frank Klaus-Peter , Strähle Joachim
Published: March 2015

The reaction of WCl6 or ReCl5 with NH4Cl in a sealed glas ampoule between 350 and 400 °C yields the hexachlorometallates(IV ) (NH4)2MCl6. MoCl5 forms (NH4)2MoC16 at 275 °C, whereas at 420 °C (NH4)3Mo2C19 is obtained. The salts (NH4)2MC16 crystallize in the K2PtCl6 type structure. NbBr5, WBr6 and Tal5 undergo ammonolysis reactions with NH4
+ forming the nitrido complexes M2NX10
3- with a symmetrical nitrido bridge M = N = M . The com plexes have the point symmetry D4h. (NH4)3Nb2NBr10 crystallizes in the tetragonal space group P4/mnc with a = 727.8, c = 1932.9 pm and Z = 2. For (NH4)3Ta2NI10 a partially disordered structure in the tetragonal space group I4/mmm was observed. The lattice constants are a - 162.5, c - 1990.2 pm, Z = 2. (NH4)3W2NBr10 was obtained in the form of an am orphous powder. The vibrational spectra of the nitrido com plexes are assigned and discussed
Nitriles in Heterocyclic Synthesis: Novel Syntheses of Functionally Substituted Isoxazoles, Pyrazoles, Pyrazines and their Condensed Derivatives
Authors: Ghozlan Said Ahmed Soliman , Aal Fatma Abd El Maksoud Abd El , Mohamed Mona Hassan , Elnagdi Mohamed Hilmy
Published: March 2015

Novel syntheses of functionally substituted isoxazoles, pyrazoles and pyrazines have been reported utilizing ethyl tosyloximinoglyoxalate (1) and the pyridinium salt 2 as starting materials. Functionally substituted nitriles are versatile reagents and their utility in heterocyclic synthesis has received considerable recent attention [3 - 7]. In previous work we have reported several new approaches for the synthesis of azoles, azines and azoloazines utilizing simple readily obtainable polyfunctional nitriles as starting materials [8-12]. Although 1 and 2 can be readily prepared from ethyl cyanoacetate, however, their utility in synthesis of heterocycles has received only very little attention [1, 2, 13-16]
Beiträge zur Strukturchemie phosphorhaltiger Ketten und Ringe, XIII [1]. Die Molekül- und Kristallstruktur von 3,4,9,10-Tetraisopropylpentacyclo[ 6.4.0.02,6.05,12.07,11]dodecaphosphan, P12(i-Pr)4 / Structural Chemistry of Phosphorus-Containing Chains and Rings, XIII [1]. The Molecular and Crystal Structure of 3,4,9,10-Tetraisopropylpentacyclo[6.4.0.02,6.05,12.07,11]dodecaphosphane, P12(iPr)4
Authors: Tebbe Karl-Friedrich , Fehér Magda
Published: March 2015

The structure of P12(iPr)4, C12H28P12 , has been determined by single crystal X-ray techniques (Rf = 0.026, wRf = 0.029 for 3549 observed reflections with |Fo| ≥ 4σ(Fo)). The compound crystallizes in the triclinic space group P1 with a = 879.8, b = 1088.5, c = 1414.1 pm, α = 93.01, β - 107.61, γ = 92.92° and Z = 2. The molecule contains a polycyclic P12-unit of nearly C2v symmetry, which represents an essential structural unit of Hittorf’s phosphorus.
S4N4 und seine Derivate: Isolierung und Struktur von S4N4H+[SnCl5(H2O)]– und (S3N2NH2
+)2[SnCl6]2– / S4N4 and its Derivatives: Isolation and Structure of S4N4H+[SnCl5(H2O)]- and (S3N2NH2
+)2[SnCl6]2-
Authors: Holl Konrad , Thewalt Ulf
Published: March 2015

Among the reaction products of S4N4 with SnCl4 in chloroform, that contains acetic acid and small amounts of water, there are two salts S4N4H+[SnCl5(H2O)]- (A) and (S3N2NH2
+)2[SnCl6]2- (B), both containing protonated SnNm units. The crystal and molecular structures of A and B have been determined by X-ray diffraction. A: monoclinic, P21/c, a = 9.084(2), b - 23.758(4), c = 6.587(1) Å , β = 101.86(3)°, Dc = 2.383 g·cm-3 and Z = 4. B: monoclinic, P21/n, a = 9.882(3), b = 12.873(4), c = 6.807(2) Å , β = 93.77(5)°, Dc = 2.352 g·cm-3 and Z = 2. The structures of the cations in both compounds agree well with those found of other salts containing these cations.
Gehinderte Ligandbewegungen in Übergangsmetallkomplexen, XXXI [1]. Synthese und Dynamik von Acetyl-carbonyl-η5-cyclopentadienyl-η4-dien-wolfram-Komplexen / Hindered Ligand Movements in Transition Metal Complexes, XXXI [1]. Syntheses and Dynamics of Acetyl-carbonyl-η5-cyclopentadienyl-η4-diene-tungsten Complexes
Authors: Kreiter Cornelius G. , Nist Kurt , Kögler Joachim
Published: March 2015

Tricarbonyl-η5-cyclopentadienyl-methyl-tungsten (1) reacts upon UV irradiation with conjugated dienes, like 1,3-butadiene (2), E-1,3-pentadiene (3), 2-methyl-1,3-butadiene (4), 2,3-dimethyl-1,3- butadiene (5), 1,3-cyclopentadiene (6) and 1,3-cyclohexadiene (7), to give the corresponding, quasisquare- pyramidal [(η5-C5H5)W(CO)(COCH3)(η4-diene)] complexes (8-13). With the unsymmetrically substituted dienes 3 and 4, only one of the possible diastereotopic complexes are obtained. At 200 to 230 K, 8-12 show two isomers, which are distinguished by the orientations (o or u) of the diene with respect to the other ligands. The interconversion of the o- and u-isomers was studied by dynamic 1H NMR spectroscopy and is explained by an intramolecular ±180° rotation of the diene ligands in the molecular plane. The barriers o f activation ⊿G* 300 are between 57.8 and 61.0 ± 1 kJ/mol.
Die oxidative Spaltung von Pseudobasen 2-α-alkylierter 2,3-Cycloalkenopyridinium-Salze / Oxidative Cleavage of Pseudobases from 2-α-Alkylated 2,3-Cycloalkenopyridinium Salts
Authors: Weber Horst , Lippe Gotelind von der , Matyja Magdalena
Published: March 2015

In contrast to former assumptions pyridinium salts with a tertiary 2-α-C-atom like 2 a and 16 are not oxidized to pyridinium-carbinol intermediates during alkaline hexacyanoferrate(III) oxidation because 10 yields the pyridones 11 and 12, both missing after oxidation of 2a. The title compounds 2 show the same reactivity against alkaline hexacyanoferrate(III). The pseudobases 14 suffer ring fission simultaneously forming the pyridones 6-8. 4 and 5 were characterized as further oxidation products of 2.
Schwefeldioxid als Brückenligand zwischen zwei verschiedenen Metallatomen [1] / Sulfur Dioxide as Bridging Ligand Between Two Different Metal Atoms [1]
Authors: Schenk Wolfdieter A.
Published: March 2015

The compound MoRhCl(μ-dppm)2(CO)2(μ-CO)(M-SO2) (1) is ob­tained from MoRhCl(μ-dppm)2(CO)4 and SO2. 1 is the first hetero-bimetallic complex of sulfur dioxide.
η5-2,3-Dihydro-1,3-diborol-Komplexe des Rhodiums [1] / η5-2,3-Dihydro-1,3-diborole Complexes of Rhodium [1]
Authors: Geilich Klaus , Siebert Walter
Published: March 2015

Reaction between [(C2H4)2RhCl]2 and the 2,3-dihydro-1.3-diborole derivative 1 yields [(l)RhCl]2 (3). In 3 the chloro-bridge can be replaced by the 2,3-dihydro-l,3-diborolyl(1-H) or by the cyclopentadienyl group to give the sandwich complexes 4 and 5, respectively. The complexes 3-5 contain a penta-coordinated carbon atom in the ligand 1. 1H and 11B NMR data are reported.