bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Versatility of Lithium Reagents in Synthetic Organometallic Chemistry: Their differing reactions with [Cp*Mo(NO)(CH2SiMe3)2]
Authors: Legzdins Peter , Sayers Stephen F. 
Published: July 2007

Abstract[Cp*Mo(NO)(CH2SiMe3)2] exhibits three principal types of reaction with the various lithium reagents investigated during this study, namely: regioselective deprotonation, reduction, and addition. Deprotonation of the reactant, achieved by treatment with lithium amide reagents, leads ultimately to the formation of the alkylidene „ate”︁ complex [Cp*Mo(NO)(CH2SiMe3)2(CHSiMe3)]2‐[Li2(thf)3] (1). While LiN(SiMe3)2 effects this conversion directly with no detectable intermediates, reaction with 1 equiv of LDA in THF for 15 min deprotonates the Cp* ligand to form the lithium salt of the „tucked‐in”︁ ate complex [(η5,η1‐C5Me4CH2)Mo(NO)(CH2SiMe3)2]‐[Li(thf)3] (2) in 40% isolated yield. Complex 2 slowly converts to the thermodynamically more stable 1 when left as a THF or C6D6 solution at ambient temperature for 48 h. Reaction of the dialkyl starting material with either tBuLi or PhLi leads to the production of the alkylidene complex 1 in irreproducible yields (10–50% NMR; not isolable). A kinetic analysis of the reaction of [Cp*Mo(NO)(CH2SiMe3)2] with LiN(SiMe3)2 indicated that the reaction was first‐order in both the lithium and molybdenum reagents, and the activation parameters of ΔH* = 7.3∓1.0 kcal mol−1 and ΔS* = − 34∓3 e.u. suggest an associative process. Treatment of the neutral dialkyl with 1 equiv of LiPPh2 in THF results in a one‐electron reduction and production of {[Cp*Mo(NO)(CH2SiMe3)2[Li2(thf)3] (3). If left in solution, the 17e− dialkyl anion 3 is converted to the 18e− alkylidene anion 1 by the Ph2P–PPh2 coproduct, which effects the requisite hydrogen‐atom abstraction. Finally, addition of a sterically undemanding alkyllithium reagent such as MeLi to the 16e− dialkyl reactant leads to the formation of the 18e− trialkyl anionic complex [[Cp*Mo(NO)(CH2SiMe3)2(CHSiMe3)]2‐[Li2(thf)3](Me)][Li(thf)3] (4). Warming of 4 in a C6D6 solution results in loss of methane and production of 1. In most cases, the chemistry exhibited by the Mo system is duplicated by the analogous W congener, [Cp*Mo(NO)(CH2SiMe3)2(CHSiMe3)]2‐[Li2(thf)3]. The solid‐state molecular structures of complexes 1 and 4 have been established by single‐crystal X‐ray crystallographic analyses.
The Comparative Solvatochromism of Arylazo and Heteroarylazo Compounds Based On N,N‐Diethyl‐m‐acetylaminoaniline and N,N‐Diethyl‐m‐toluidine
Authors: Hutchings Michael G. , Gregory Peter , Campbell James S. , Strong Andrew , Zamy Jean‐Paul , Lepre Anne , Mills Andrew 
Published: July 2007

AbstractAzobenzene dyes derived from various anilines and aminothiaheterocycles azo‐coupled with commercially important N,N‐diethyl‐m‐toluidine (T series) and N,N‐diethyl‐m‐acetylaminoani‐line (A series) are positively solva‐tochromic. The visible spectra of 16 pairs of derivatives have been measured in up to 22 solvents, and the transition energies related to Kamlet‐Taft solvent polarity parameters. In general, A‐series dyes are more bathochromic than their T‐series counterparts in nonpolar solvents, consistent with colour chemistry tradition. However, in more dipolar solvents the more bathochromic T‐series representatives unexpectedly become more bathochromic than their A‐series partners. The relative solvatochromic shifts of the A and T series are related to their respective dipole moments. These in turn are distinguished by the effect of the anilide carbonyl group dipole moment, which is antiparallel to, and thus reduces, the dipole moment of the chromogen.
Proof of Inversion of Configuration on Stannylation of a Configurationally Stable, Tertiary Benzyllithium Compound from a Single‐Crystal X‐Ray Structure Analysis
Authors: Hammerschmidt F. , Hanninger A. , Völlenke H. 
Published: July 2007

AbstractConfigurationally stable, dipole‐stabilised benzyllithium compounds (R)‐and (S)‐1 b, prepared by deprotonation of the corresponding esters with sBuLi in toluene/di‐ethyl ether (5:1), reacted with (–)‐menthyldimethyltin bromide to afford the stannanes (–)‐3 and ( + )‐4, respectively. A single‐crystal X‐ray structure analysis of compound (–)‐3 proved that stannylation occurred with inversion of the configuration at the benzylic centre, assuming retention for the deprotonation step. Lithio‐destannylation and deuteration with MeOD follow a retentive course.
The Quest For Extra‐Large Pore, Crystalline Molecular Sieves
Authors: Davis Mark E. 
Published: July 2007

AbstractThe definition and reasons for desiring extralarge pore, crystalline molecular sieves are ennumerated. A historical perspective on the development of these materials is presented with emphasis on critical features important for practical application. Based on the known physiochemical properties of extra‐large pore materials, several avenues for their synthesis are suggested. Finally, a few issues of concern when dealing with this class of materials are presented.
Gold Clusters and Colloids in Alumina Nanotubes
Authors: Hornyak Gabor , Kröll Michael , Pugin Raphael , Sawitowski Thomas , Schmid Günter , Bovin Jan‐Olov , Karsson Gunnel , Hofmeister Herbert , Hopfe Sigrid 
Published: July 2007

AbstractThe fabrication of a supported and insulated quantum wire would be of great interest, especially if electronic information could be accessed to determine charging and conductivity profiles. The feasibility of forming one‐dimensional configurations of ≈ 15 nm gold colloids and 1.4 nm gold clusters via template methods of synthesis has now been demonstrated. The template host material consisted of porous alumina membranes formed by an electrochemical anodic process. The pores of the membrane, and hence the parallel pore channels, were packed in a hexagonal array. Alumina membranes are excellent template materials because of their high degree of order, thermal and chemical stability, and optical clarity. Pore diameter was controlled by regulation of the applied anodic potential (ca. 1.4 nm V‐1). The pore channels were filled by one of three methods: vacuum induction (colloids only), electrophoresis (clusters only), or immersion (clusters, which were then converted into colloids by heating). Rudimentary wires consisting of colloids and clusters were successfully formed. In both cases, the diameter of the pore channel exceeded that of the clusters or colloids. The wires thus formed conformed to the pore channel by forming helical secondary structures. It was not possible to form contiguous wires of clusters by immersion, or of colloids formed from clusters after heating. Composites (consisting of the gold‐alumina system) were a bright scarlet color with an absorption maximum (λmax) at 519.5 nm. This is an unexpected result for spherical and small‐diameter (10 nm) gold colloids, which normally absorb at λmax 525–530 nm, a ruby‐red color. Possible causes of this small but remarkable blue shift are discussed below. A new Au55 cluster ligand system consisting of a silsesquioxane‐derivatized thiol is also described.
Polymeric [(Me3Sn)3Rh(SCN)6]: A Novel “Super‐Prussian‐Blue” Derivative Containing the Nonlinear ‐SCN‐Sn‐NCS‐ Spacer
Authors: Siebel Eric , Fischer R. Dieter 
Published: July 2007

AbstractThe new coordination polymer [(Me3SnIV)3RhIII(SCN)6] = [Rh{μ‐(SCNSnMe3NCS)}3] (5) is readily accessible by straightforward self‐assembly of [Rh(SCN)6]3‐ and (dehydrated) {Me3Sn} ions. The architecture of 5 is strongly reminiscent of “super‐Prussian‐blue” systems reported earlier: there is a three‐dimensional (3‐D) framework involving {Rh8} pseudocubes as the basic building blocks, the Rh3+ ions being held apart by novel, nonlinear {SCN‐SnMe3‐NCS} spacers (d(Rh…︁Rh) = 1.27 nm). The complete lattice consists of two equivalent and independent, ideally interwoven 3‐D frameworks. Three homologues of 5 with slightly modified R3Sn units (R = Et, nPr and nBu) have been prepared as well, but display X‐ray powder diffraction patterns notably different from that of 5.
(CuI)2Cu3SbS3: Copper Iodide as Solid Solvent for Thiometalate ions
Authors: Pfitzner Arno 
Published: July 2007

Abstract(CuI)2Cu3SbS3 was prepared by solid‐state reaction of stoichiometric amounts of CuI, Cu, S, and Sb. The crystal structure was determined from single crystals at room temperature and ‐ 80°C. Red‐orange (CuI)2Cu3SbS3 crystallizes in the orthorhombic system, space group Pnnm (no. 58) with a = 10.488(2), b = 12.619(2), c = 7.316(1) Å, V = 968.2(2) Å3 (20°C), and Z = 4. The distribution of the copper atoms was refined by using a Gram‐Charlier nonharmonic development of their atomic displacement parameters, which indicated an increasing dynamic disorder from ‐80°C to 20°C. Raman spectra of (CuI)2Cu3SbS3 are dominated by strong bands for [SbS3]3‐ units at 362 and 338 cm‐1. The compound melts at 492°C (DTA, onset). Conductivity measurements reveal high ionic conductivity (6.2 × 10‐5ω‐1 cm‐1 at 50°C, 2.9 × 10‐3 ω‐1 cm‐1 at 200°C) with an activation energy of 0.35 eV (40–275°C).
Local presentation of L1 and N‐cadherin in multicomponent, microscale patterns differentially direct neuron function in vitro
Authors: Shi Peng , Shen Keyue , Kam Lance C. 
Published: July 2007

AbstractThe ability to pattern multiple bioactive cues on a surface is valuable for understanding how neurons interact with their complex extracellular environment. In this report, we introduce a set of methods for creating such surfaces, with the goals of understanding how developing neurons integrate multiple biologically relevant signals and as a tool for studying interactions between multiple neurons. Multiple microcontact printing steps are combined on a single surface to produce an array of polylysine nodes, interconnected by lines of proteins based on the extracellular domains of L1 or N‐cadherin. Surprisingly, the N‐cadherin protein could also be directly printed onto surfaces while retaining its biological activity. Rat hippocampal neurons selectively attached to the polylysine nodes, differentially extending axonal and dendritic processes along the patterns of L1 and N‐cadherin, thus demonstrating control over neuron attachment and outgrowth. Combining these three biomolecules on a single surface revealed a highly complex pattern of protein recognition. Dendrites extended exclusively on N‐cadherin patterns, while axons exhibited a very high degree of selectivity on L1 patterns, preferentially at distances greater than 55 μm from the cell body. At shorter distances, axonal processes recognized both L1 and N‐cadherin, revealing a new aspect of neuron polarity and axon specification. This onset of L1 selectivity correlated with the establishment of intracellular L1 polarity, suggesting a functional outcome of the process of neuron polarization that has implications in development of neural tissues and creation of in vitro neuron networks. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007.
Summary of ‘Antibiotics for the prevention of acute and chronic suppurative otitis media in children’
Authors: Milne Andrea 
Published: July 2007

AbstractThis is a summary of a Cochrane review, published in this issue of EBCH, first published as: Leach AJ, Morris PS. Antibiotics for the prevention of acute and chronic suppurative otitis media in children. Cochrane Database of Systematic Reviews 2006, Issue 4. Art. No.: CD004401. DOI: 10.1002/14651858.CD004401.pub2.Further information for this Cochrane review is available in this issue of EBCH in the accompanying Commentary and Characteristics and Key Findings Tables articles. Copyright © 2007 John Wiley & Sons, Ltd.
Summary of ‘Modification of the home environment for the reduction of injuries’
Authors: Milne Andrea 
Published: July 2007

AbstractThis is a summary of a Cochrane review, published in this issue of EBCH, first published as: Lyons RA, John A, Brophy S, Jones SJ, Johansen A, Kemp A, Lannon S, Patterson J, Rolfe B, Sander LV, Weightman A. Modification of the home environment for the reduction of injuries. Cochrane Database of Systematic Reviews 2006, Issue 4. Art. No.: CD003600. DOI: 10.1002/14651858.CD003600.pub2.Further information for this Cochrane review is available in this issue of EBCH in the accompanying Commentary and Characteristics and Key Findings Tables articles. Copyright © 2007 John Wiley & Sons, Ltd.
Summary of ‘Written action plans for asthma in children’
Authors: Milne Andrea 
Published: July 2007

AbstractThis is a summary of a Cochrane review, published in this issue of EBCH, first published as: Bhogal S, Zemek R, Ducharme FM. Written action plans for asthma in children. Cochrane Database of Systematic Reviews 2006, Issue 3. Art. No.: CD005306. DOI: 10.1002/14651858.CD005306.pub2.Further information for this Cochrane review is available in this issue of EBCH in the accompanying Commentary and Characteristics and Key Findings Tables articles. Copyright © 2007 John Wiley & Sons, Ltd.
Commentary on ‘Antibiotics for the prevention of acute and chronic suppurative otitis media in children’, with response from review author
Authors: van Benthem Peter Paul G. 
Published: July 2007

AbstractThis is a commentary on a Cochrane review, published in this issue of EBCH, first published as: Leach AJ, Morris PS. Antibiotics for the prevention of acute and chronic suppurative otitis media in children. Cochrane Database of Systematic Reviews 2006, Issue 4. Art. No.: CD004401. DOI: 10.1002/14651858.CD004401.pub2.Further information for this Cochrane review is available in this issue of EBCH in the accompanying EBCH Summary and Characteristics and Key Findings Tables articles. Copyright © 2007 John Wiley & Sons, Ltd.
Commentary on ‘Nitric oxide for respiratory failure for infants born at or near term’
Authors: Cools Filip 
Published: July 2007

AbstractThis is a commentary on a Cochrane review, published in this issue of EBCH, first published as: Finer NN, Barrington KJ. Nitric oxide for respiratory failure in infants born at or near term. Cochrane Database of Systematic Reviews 2006, Issue 4. Art. No.: CD000399. DOI: 10.1002/14 651 858.CD000399.pub2.Further information for this Cochrane review is available in this issue of EBCH in the accompanying EBCH Summary and Characteristics and Key Findings Tables articles. Copyright © 2007 John Wiley & Sons, Ltd.
Commentary on ‘Systemic antibiotics versus topical treatments for chronically discharging ears with underlying eardrum perforations’
Authors: Schilder Anne G. M. , Sanders Elisabeth A. M. 
Published: July 2007

AbstractThis is a commentary on a Cochrane review, published in this issue of EBCH, first published as: Macfadyen CA, Acuin JM, Gamble C. Systemic antibiotics versus topical treatments for chronically discharging ears with underlying eardrum perforations. Cochrane Database of Systematic Reviews 2006, Issue 1. Art. No.: CD005608. DOI: 10.1002/14 651 858.CD005608.Further information for this Cochrane review is available in this issue of EBCH in the accompanying EBCH Summary and Characteristics and Key Findings Tables articles. Copyright © 2007 John Wiley & Sons, Ltd.
Characteristics and key findings for ‘Written action plans for asthma in children’
Authors: van Dalen Elvira , Offringa Martin , Kremer Leontien 
Published: July 2007

AbstractThese are the characteristics and key findings for a Cochrane review, published in this issue of EBCH, first published as: Bhogal S, Zemek R, Ducharme FM. Written action plans for asthma in children. Cochrane Database of Systematic Reviews 2006, Issue 3. Art. No.: CD005306. DOI: 10.1002/14 651 858.CD005306.pub2.Further information for this Cochrane review is available in this issue of EBCH in the accompanying EBCH Summary and Commentary articles. Copyright © 2007 John Wiley & Sons, Ltd.
Characteristics and key findings for ‘Systemic antibiotics versus topical treatments for chronically discharging ears with underlying eardrum perforations’
Authors: van Dalen Elvira , Offringa Martin , Kremer Leontien 
Published: July 2007

AbstractThese are the characteristics and key findings for a Cochrane review, published in this issue of EBCH, first published as: Macfadyen CA, Acuin JM, Gamble C. Systemic antibiotics versus topical treatments for chronically discharging ears with underlying eardrum perforations. Cochrane Database of Systematic Reviews 2006, Issue 1. Art. No.: CD005608. DOI: 10.1002/14 651 858.CD005608.Further information for this Cochrane review is available in this issue of EBCH in the accompanying EBCH Summary and Commentary articles. Copyright © 2007 John Wiley & Sons, Ltd.
Probabilistic evaluation of global seismic capacity of degrading structures
Authors: Koduru S. D. , Haukaas T. , Elwood K. J. 
Published: July 2007

AbstractThe present study addresses the probabilistic seismic capacity evaluation of the existing non‐ductile reinforced concrete structures that are vulnerable to shear, and thus axial, failures of their columns. The probability of structural collapse at a target lateral displacement imposed by seismic hazard is estimated by reliability analysis. For this purpose, the prevalent nonlinear static procedure is extended with finite element reliability analysis. The global structural model is enhanced by incorporating probabilistic capacity and post‐failure response models of individual columns. The challenges in the detection of collapse and the potential problems and remedies in the reliability analysis due to ‘gradient discontinuities’ are presented. In particular, ‘smoothing’ of the post‐failure response models is implemented to represent realistic member behaviour and to avoid non‐convergence in the reliability analysis. Finally, parameter importance measures are employed to identify the parameters with the highest contribution to the uncertainty in the structural performance. Copyright © 2007 John Wiley & Sons, Ltd.
A quantitative overview of glucose dynamics in the gliovascular unit
Authors: Barros L. F. , Bittner Carla X. , Loaiza Anitsi , Porras Omar H. 
Published: July 2007

AbstractWhile glucose is constantly being “pulled” into the brain by hexokinase, its flux across the blood brain barrier (BBB) is allowed by facilitative carriers of the GLUT family. Starting from the microscopic properties of GLUT carriers, and within the constraints imposed by the available experimental data, chiefly NMR spectroscopy, we have generated a numerical model that reveals several hidden features of glucose transport and metabolism in the brain. The half‐saturation constant of glucose uptake into the brain (Kt) is close to 8 mM. GLUT carriers at the BBB are symmetric, show accelerated‐exchange, and a Km of zero‐trans flux (Kzt) close to 5 mM, determining a ratio of 3.6 between maximum transport rate and net glucose flux (Tmax/CMRglc). In spite of the low transporter occupancy, the model shows that for a stimulated hexokinase to pull more glucose into the brain, the number or activity of GLUT carriers must also increase, particularly at the BBB. The endothelium is therefore predicted to be a key modulated element for the fast control of energy metabolism. In addition, the simulations help to explain why mild hypoglycemia may be asymptomatic and reveal that [glucose]brain (as measured by NMR) should be much more sensitive than glucose flux (as measured by PET) as an indicator of GLUT1 deficiency. In summary, available data from various sources has been integrated in a predictive model based on the microscopic properties of GLUT carriers. © 2007 Wiley‐Liss, Inc.
Kleine Ringe, 86. Versuche zur Darstellung von Alkyltri‐tert‐butyltetrahedranen auf dem Cyclopentadienon‐Weg; photochemisches Verhalten der Cyclopentadienone
Authors: Maier G. , Franz L. H. , Boese Roland 
Published: July 2007

Small Rings, 86. – Attempts to Synthesize Alkyltri‐tert‐butyltetrahedranes by the Cyclopentadienone Route; Photochemical Behavior of the CyclopentadienonesOnly the Tetra‐tert‐butyltetrahedranes 8a–c can be synthesized by photochemical CO extrusion from the corresponding cyclopentadienones 6a–c. This strategy fails with other cyclopentadienones like 6d–f.
Kleine Ringe, 87. Suche nach alternativen Wegen zum Tetra‐tert‐butyltetrahedran; Synthese sterisch überladener Verbindungen
Authors: Maier Günther , Rang Harald , Emrich Rolf 
Published: July 2007

Small Rings, 87. – Search for Alternative Routes to Tetra‐tert‐butyltetrahedrane; Synthesis of Sterically Overcrowded MoleculesKetene 3 can be isomerized to triclopentanone 2 by treatment with silica gel. Thus, the yield of tetrahedrane 5, which is formed upon irradiation of 2, has been improved. On the other hand, diazoketone 10 cannot be used as a precursor for 2. This failure is due to steric hindrance. For the same reason cyclobutadiene 4 is a very poor candidate for Diels‐Alder cycloadditions.
Kleine Ringe, 88. Reaktionen von Tetra‐tert‐butyltetrahedran: Oxidation zum Radikal‐Kation als einleitender Schritt
Authors: Maier Günther , Rang Herald , Emrich Rolf , Gries Stefan , Irngartinger Hermann 
Published: July 2007

Small Rings, 88. – Reactions of Tetra‐tert‐butyltetrahedrane: Oxidation to the Radical Cation as the First StepThe chemistry of tetrahedrane 1 and cyclobutadiene 3 is governed by the initial formation of radical cation 2. In spite of the high steric hindrance 2 cannot be isolated as a radical‐ion pair. Reaction of 3 with O2 generates the oxete 21 which is surprisingly stable (up to 200°C).
Kleine Ringe, 90. Peralkyl‐substituierte Tetrahedrane
Authors: Maier Günther , Fleischer Frank , Kalinowski Hans‐Otto 
Published: July 2007

Small Rings, 90. – Peralkyl‐Substituted TetrahedranesPhotolysis of the diazo compounds 4a, b generates adaman‐tyltri‐tert‐butyltetrahedrane (9a) and tri‐tert‐butylisopropyltetrahedrane (9b), and the corresponding cyclobutadienes 10a, b. In contrast to tetrahedrane 9a, which results from an intramolecular addition in carbene 7a and also from photoisomerization of cyclobutadiene 10a, the only source for tetrahedrane 9b is the cheletropic cycloaddition of the carbenic center to the cyclopropene double bond in the photochemically produced carbene 7b. Tetrahedrane 9b is remarkable in its kinetic and thermal instability, which is caused by the reduced „corset effect”︁ in this compound. An additional access to this tetrahedrane is possible via the diazomethanes 34A and 34B. The pyridazines 17b and 41, which are formed by thermolysis of the diazo compounds 4b, 34A and 34B lead to the azetes 19 and 43. Last but not least 17b and 41 are interesting molecules themselves because of their inherent chirality.
Terpenes and terpene derivatives, XXXIII. Synthesis of rac‐cis‐ and ‐trans‐dracunculifoliol and their 10‐epimers
Authors: Weyerstahl Peter , Marschall Helga , Schneider Kathleen 
Published: July 2007

AbstractThe cis‐aldehyde 9, a key intermediate in the total synthesis of cis‐dracunculifoliol (1) previously isolated from Vassoura oil, was prepared starting from the bicyclic enone 5 via the nitrile 8. Grignard reaction of 9 led exclusively to epi‐1. Oxidation to the ketone 10 followed by reduction gave a separable mixture of the natural isomer 1 and epi‐1. – The synthesis of trans‐dracunculifoliol (2) starts with the 6‐methoxytetralone 14. After some usual steps, the trans‐octalin 17 was obtained. MMPP‐HIO4 oxidation gave compound 19 which was transformed into the iodo ester 26, precursor of the hydrindane ester 27. Analogously to the synthesis of epi‐1 the epi‐trans‐dracunculifoliol (epi‐2) was formed via alcohol 28 and aldehyde 29. Oxidation ( 30) and reduction furnished the natural trans alcohol 2. – Olfactory evaluation of the purified isomers 1, epi‐1, 2, and epi‐2 showed that all of them possess only a weak, woody odor. Therefore, the dracunculifoliols 1 and 2 are not responsible for the typical earthy, leathery, and spicy odor of the Vassoura oil.