bluuebunny/crossref_metadata_2025_split huggingface dataset:
Steric and Electronic Control of Ligand Field Strength in Octahedral Co3+ Spin‐Crossover Complexes
Authors: Eberspach Werner , Murr Nabil El , Kläui Wolfgang 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1943. DOI:10.1002/anie.198219430
Stabilization of the Unstable Tautomers of Phosphino‐ and Arsino‐Substituted Ylides by Coordination to Transition Metals
Authors: Weber Lothar , Boese Roland , Meyer Wolfgang 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 1934. DOI:10.1002/anie.198219340
Kinetic and Thermodynamic Control in the Reaction of (Ph3P)2PtO2 with (E)‐2‐Butenal
Authors: Broadhurst Michael J. , Brown John M. , John Robert A. 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1. DOI:10.1002/anie.198300010
Intermetallic Compounds and the Use of Atomic Radii in Their Description
Authors: Simon Arndt 
Published: December 2003

AbstractMetallic radii, which are obtained from atomic distances in the pure elements, are generally used for the calculation of distances in intermetallic compounds. However, the procedure for using such radii depends on the individual structural type: (a) For high coordination numbers and only slightly differing distances between atoms of the same kind and different atoms, all distances in a structure are proportional to the sum of radii, weighted according to the compositon. Such a “Vegard” relationship for ordered compounds is obeyed by intermetallic compounds with topological close packings, but strictly only if the various kinds of distances are correlated via symmetry relationships. For compounds with low coordination numbers the simple sum of radii holds for atoms participating in the shortest bond (e.g. in ionic crystals).‐(b) The number of neighbors determines the size of each atom. It can be shown that the bond strength‐bond length concept, developed for valence compounds, and often dealt with in the literature over the last ten years, is also applicable for alloys. On this basis a formalism is developed which uniformly describes the size of the atoms as a function of the coordination number for both the limiting cases of multiple bonds in molecules and for close packed atomic arrangements in alloys.
Catalysis by Molecular Metal Clusters
Authors: Muetterties Earl L. , Krause Michael J. 
Published: December 2003

AbstractMolecular metal clusters form a very large and diverse family. They present the opportunity of modeling the intermediates involved in surface mediated catalytic reactions, of providing a source of very reactive mononuclear metal fragments, and of effecting catalytic cycles in which the cluster remains intact. The last mentioned aspect is the subject of this review article. The state‐of‐the‐art of cluster catalysis is critically analyzed. The possibilities offered by molecular metal catalysts of performing catalytic reactions at multimetal atom sites are also discussed.
Chromatographic Resolution of Cyclic Organic Compounds on a Λ‐Tris(1,10‐phenanthroline)ruthenium(II) Montmorillonite Column
Authors: Yamagishi Akihiko , Ohnishi Ryuichiro 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 140. DOI:10.1002/anie.198301400
FT‐FIR Spectroscopy of Ligand‐Free Metal Clusters; Matrix Effects on the Molecular Geometry of Trichromium, Cr3
Authors: Ozin Geoffrey A. , Baker Mark D. , Mitchell Steven A. , McIntosh Douglas F. 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 92. DOI:10.1002/anie.198300920
The Versatile Chemistry of 1,4‐Diazines: Organic, Inorganic and Biochemical Aspects
Authors: Kaim Wolfgang 
Published: December 2003

AbstractIn chemical research attention is increasingly being focussed on composite “complex” systems with special properties and functions. As components of such systems 1,4‐diazines are steadily gaining in popularity. Here, 1,4‐diazines means pyrazine and its derivatives as well as compounds with partial pyrazine structure; examples are quinoxaline, phenazine, pteridine, flavin and their derivatives. All these compounds are characterized by a low lying unoccupied π‐molecular orbital and by the ability to act as bridging ligand. Due to these two properties 1,4‐diazines, and especially their parent compound pyrazine, possess a characteristic reactivity. 1,4‐Diazines may be employed to study inter‐ and intramolecular electron transfer in organic, inorganic and biochemical reactions. In the redox system of 1,4‐diazines the paramagnetic 7π‐electron intermediate exhibits exceptional stability, whereas the 1,4‐dihydro‐1,4‐diazines with 8π‐electrons in a six‐membered ring are not generally accessible due to their potential antiaromaticity and their large excess of π electrons. Its inherent bifunctionality and the low lying unoccupied molecular orbital permit pyrazine to form coordination polymers having unusual electrical and magnetic properties. Finally, the phenomena observed for pyrazines may be used in the interpretation of the reactivity of naturally occurring 1,4‐diazines, such as flavins and bioluminescent natural products.
Symmetry Breaking and Non‐Born‐Oppenheimer Effects in Radical Cations
Authors: Köppel Horst , Cederbaum Lorenz S. , Domcke Wolfgang , Shaik Sason S. 
Published: December 2003

AbstractThe various electronic states in which molecules can exist are often considered to be independent. In this article we turn our attention to the limitations of this assumption, namely the interaction between different electronic states through the nuclear motion. This interaction can have several important consequences, two of which are discussed in some detail. One is a distortion of the molecular framework, leading to a lowering of the symmetry of a molecule in excited or ionic states compared to the neutral ground state. General aspects of this symmetry lowering are outlined and interpreted with the aid of typical examples. The other consequence considered is the ability of the nuclei to “jump” between different molecular potential energy surfaces (non‐Born‐Oppenheimer effects). The nature of this behavior is analyzed and it is argued that the “jumping” can be very fast and efficient, dominating completely the nuclear motion. To exemplify our general ideas we refer to the photoelectron spectra of ethylene and related compounds and demonstrate that they are governed by strong non‐Born‐Oppenheimer effects. It emerges that the Franck‐Condon principle fails in the analysis of their vibronic structure.
Carbonyl Olefinations with Organomolybdenum Compounds
Authors: Kauffmann Thomas , Ennen Beate , Sander Jörg , Wieschollek Raphael 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 222. DOI:10.1002/anie.198302220
Zircona‐ and Hafnacyclobutenes—A New Route to Metallacyclobutanes
Authors: Seetz Johannes W. F. L. , Schat Gerrit , Akkerman Otto S. , Bickelhaupt Friedrich 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 234. DOI:10.1002/anie.198302340
Synthesis and Structure of [AsPh4][Ru6H(μ‐OCNMe2)2(μ‐CO)4‐(CO)14]·Me2CO; A Cyclic Hydrido‐Hexametallic Anion
Authors: Boag Neil M. , Knobler Carolyn B. , Kaesz Herbert D. 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 198. DOI:10.1002/anie.198301980
1,5‐Dimethylverdazyls, Hydrazidinyl Radicals with Pyramidal 1,5‐Nitrogen Atoms
Authors: Neugebauer Franz A. , Siegel Rolf 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 457. DOI:10.1002/anie.198304570
Enantioselective Hydrosilylation of Acetophenone with Rhodium/Thiazolidine Catalysts
Authors: Brunner Henri , Riepl Georg , Weitzer Helgard 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 445. DOI:10.1002/anie.198304450
Homolytic Cyclizations of N‐Chloroalkenylamines
Authors: Stella Lucien 
Published: December 2003

AbstractMany N‐chloroalkylamines with double bond(s) dissociate homolytically to give chlorine atoms and aminyl radicals which undergo intramolecular cyclization reactions. Here, the nature of the aminyl radicals (neutral, protonated, or complexed to metal salts) appears to be important. The reactivity varies strongly from one species to another, and their selectivities can be different towards addition, substitution, abstraction, or dimerization reactions. A good synthetic tool appears to be the “complexed radical”, which is generated under mild conditions. A variety of β‐functionalized, substituted, fused, or bridged azaheterocycles with alkaloid part structures thus become easily accessible in high yields, in a regio‐ and, possibly, stereoselective manner. Many examples are discussed illustrating the synthetic possibilities, limitations, and mechanistic features of this cyclization process.
Stable Carbodications
Authors: Prakash G. K. Surya , Rawdah Tarik N. , Olah George A. 
Published: December 2003

AbstractMethods developed for the generation and study of stable carbomonocations can also be employed for similar investigations on carbodications. Trivalent (classical) as well as hexacoordinate (non‐classical) carbodications studied under long‐lived ion conditions are reviewed with special emphasis on their structural features, and investigated primarily by 1H‐ and 13C‐NMR spectroscopy.
(Z)‐2‐Methoxy‐1,2‐diphenylvinyl Alcohol, A Remarkably Stable Enol
Authors: McGarrity John F. , Cretton Alex , Pinkerton Alan A. , Schwarzenbach Dieter , Flack Howard D. 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 551. DOI:10.1002/anie.198305510
Addition of a Phosphaalkyne to Metal‐Metal Multiple Bonds
Authors: Becker Gerd , Herrmann Wolfgang A. , Kalcher Willibald , Kriechbaum Gangolf W. , Pahl Claudia , Wagner C. Thomas , Ziegler Manfred L. 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 501. DOI:10.1002/anie.198305010
Reactions at the Counter Electrode in Electroreductions under Aprotic Conditions in One‐Compartment Cells
Authors: Engels Rainer , Smit Cornelis J. , van Tilborg Wim J. M. 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 691. DOI:10.1002/anie.198306910
Novel η3, σ‐Sulfur Double‐Ylide Chromium Complexes by endo‐Hydride Addition to Cationic (λ6‐Thiabenzene 1‐Oxide)chromium Complexes
Authors: Weber Lothar , Boese Roland 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 620. DOI:10.1002/anie.198306200
Four‐Membered Ring Peroxides as Excited State Equivalents: A New Dimension in Bioorganic Chemistry
Authors: Adam Waldemar , Cilento Giuseppe 
Published: December 2003

AbstractConsideration of chemiluminescent and bioluminescent processes invariably brings to mind the four‐membered ring peroxides, 1,2‐dioxetanes and α‐peroxylactones. Nevertheless, while chemiluminescence and bioluminescence are well established fields of scientific study, isolable and characterized “high‐energy” molecules such as the 1,2‐dioxetanes and α‐peroxylactones are of relatively recent vintage, about a decade. These intriguing compounds produce electronically excited products which manifest themselves by light emission during their thermal decay; more importantly, these transformations are involved in luminescent as well as dark enzymatic processes. It is not our intention to present a comprehensive overview in this progress report, but rather to focus on those aspects which require further study.
Complex Reducing Agents (CRA's)—Versatile, Novel Ways of Using Sodium Hydride in Organic Synthesis
Authors: Caubère Paul 
Published: December 2003

AbstractWhy do we hardly use the simplest and, at the same time, inexpensive reducing agent sodium hydride in organic chemistry? To this question the answer is invariably: “It is too basic”. In this progress report we describe work we have performed aimed at controlling the basicity of NaH using sodium alcoholates and metal salts. The complex reducing agents (CRA's) developed (symbolized NaH‐RONa‐MXn) allow organic halides, alkenes, alkynes and ketones to be reduced selectively. Highly regioselective 1,4‐ and 1,2‐reductions of α,β‐unsaturated ketones are easily performed using appropriate metal salts. Modified CRA's have proved to be excellent hydrosilylating reagents for carbonyl groups, non‐pyrophoric heterogeneous hydrogenation catalysts, coupling reagents for aryl and vinyl halides, and reagents for the carbonylation of organic halides under very mild conditions. The study of these reactions opened up the field to phase‐transfer‐catalyzed photostimulated carbonylations as well as to SRN1 reactions of metalates.–Thus, starting from the simple sodium hydride a large number of useful reagents have become accessible.
Solution‐Phase Metal Atom Preparation of Catalytically Active Zeolite‐Encapsulated Metal Clusters; Characterization and Application to the Selective Reduction of CO to Butene
Authors: Nazar Linda F. , Ozin Geoffrey A. , Hugues François , Godber John , Rancourt Denis 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 898. DOI:10.1002/anie.198308980
Turgorins, Hormones of the Endogeneous Daily Rhythms of Higher Organized Plants—Detection, Isolation, Structure, Synthesis, and Activity
Authors: Schildknecht Hermann 
Published: December 2003

AbstractProbably the most fascinating biological phenomenon is the movement which is so impressively observed in higher organized plants when, e.g., in a sort of “quick retreat”, the sensitive plant apparently vanishes on touching, or when all the pinnules of an acacia fold together pairwise at dusk, as though the whole tree were going to “sleep”. Such plants and trees do not possess muscles for the movement of their organs; instead of the contraction of a “still primitive” actomyosin system in this movement the hydrostatic internal pressure of the vacuoles—the turgor—in the parenchymal cells of the motile organs is often drastically and unilaterally reduced. After preception of an external stimulus there follows a gradual or sudden change in the semipermeability of the boundry plasma layers, and, mediated by a stimulus conduction, also of all the symplasts of a multicellular plant organism. The phytohormones which form the molecular basis of the physiology of movement discussed here have now been isolated and structurally elucidated. The chemical agonists of phytodynamics, referred to as turgorins, elicit leaf movement; moreover, they very probably also regulate—perhaps together with other phytohormones—the mechanism of change of aperture in stomatal transpiration. Hence, the turgorins facilitate not only a regulation of temperature, but even their own transport in the sap of the whole plant body.
Regiocontrolled Prenylations and Alkylations of Furans: Preparation of Rosefuran and Novel Analogues
Authors: Ismail Zeinhom M. , Hoffmann H. M. R. 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 985. DOI:10.1002/anie.198309850
[Me3Si(py)]⊕X⊖ (X = Br,I): X‐Ray Structural Analysis of the 1:1‐Adducts of Bromo‐ or Iodotrimethylsilane and Pyridine
Authors: Hensen Karl , Zengerly Thomas , Pickel Peter , Klebe Gerhard 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 973. DOI:10.1002/anie.198309730
Derivatization‐Free Enantiomer Resolution of Chiral Alcohols and Ketones by High‐Resolution Complexation Gas Chromatography
Authors: Schurig Volker , Weber Roland 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1130. DOI:10.1002/anie.198311300
Unprecedented Oxidative Addition of the P4S3 Cage Molecule with Phosphorus‐Phosphorus Bond Cleavage; Synthesis and Molecular Structure of [Ir(μ‐P4S3)(PPh3)Cl(CO)]2
Authors: Ghilardi Carlo A. , Midollini Stefano , Orlandini Annabella 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1066. DOI:10.1002/anie.198310660
Novel Catalytic Application of a Transition‐Metal Cluster: Spirocyclization of Alkyl Isocyanates
Authors: Süss‐Fink Georg , Herrmann Gerhard , Thewalt Ulf 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1203. DOI:10.1002/anie.198312030
1,2,4‐Thiadiazole‐3,5‐dicarbonitrile by Reaction of Cyanogen with Sulfur
Authors: Roesky Herbert W. , Keller Klaus , Bats Jan. W. 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1323. DOI:10.1002/anie.198313230
Flip‐Flop Hydrogen Bonds in β‐Cyclodextrin—A Generally Valid Principle in Polysaccharides?
Authors: Saenger Wolfram , Betzel Christian , Hingerty Brian , Brown George M. 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1191. DOI:10.1002/anie.198311910
[Ph4P]2[V2(SC2H4S)4]·4MeOH: The First Polynuclear Vanadium‐Sulfur Complex with Pure Sulfur Coordination
Authors: Szeymies Detlef , Krebs Bernt , Henkel Gerald 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1176. DOI:10.1002/anie.198311760
Radical Products in Single Electron Transfer Reactions of Lithium Triethylhydridoborate Detected by ESR and Multinuclear (1H, 10B, 11B, 14N)‐ENDOR Spectroscopy
Authors: Kaim Wolfgang , Lubitz Wolfgang 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1209. DOI:10.1002/anie.198312090
Phosphorus Ylides in the Coordination Sphere of Transition Metals: An Inventory
Authors: Schmidbaur Hubert 
Published: December 2003

AbstractPhosphorus ylides are not only classical reagents in organic chemistry, but also play an increasingly important role as novel components in organometallic compounds. These metallic “ylide complexes” are either synthesized from “preformed ylides” and coordination compounds by addition or substitution, on the building block principle, or they are formed, in sometimes complicated reactions, from phosphanes, metal complexes, and C1 substrates in the coordination sphere of the metals. The resulting metal‐carbon bonds are greatly modified in their properties by the immediate presence of the phosphonium center and often belong to the most stable of M‐C structural units. The metal can come from any group of the periodic table, including the lanthanoids and actinoids. Numerous preparative and structural studies are gradually enabling us to gain an overall picture of the scope of this area of research.
Conversion of Imidazole into μ‐2,3‐Dihydro‐1H‐imidazole‐1,2,2‐triyl Ligands
Authors: Müller Jörn , Stock Rainer 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1537. DOI:10.1002/anie.198315370
A Novel and General Route to (η5‐Borole) metal Complexes: Compounds of Manganese, Ruthenium, and Rhodium
Authors: Herberich Gerhard E. , Hessner Bernd , Boveleth Wilfried , Lüthe Herbert , Saive Roland , Zelenka Ljerka 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1503. DOI:10.1002/anie.198315030
Metal‐Induced CC Coupling by Reductive Dimerization of Thioaroyl Groups
Authors: Lindner Ekkehard , Butz Ingobert P. , Hiller Wolfgang , Fawzi Raid , Hoehne Sigurd 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1388. DOI:10.1002/anie.198313880
Octalene—Bicyclo[6.2.0]decapentaene Conversion Mediated by Transition‐Metal Complexes
Authors: Kawka Dieter , Mues Peter , Vogel Emanuel 
Published: December 2003

AbstractThe complete manuscript of this communication appears in: Angew. Chem. Suppl. 1983, 1371. DOI:10.1002/anie.198313710
The Cycloaddition of Allyl Cations to 1,3‐Dienes: General Method for the Synthesis of Seven‐Membered Carbocycles. New Synthetic Methods (40)
Authors: Hoffmann H. M. R. 
Published: December 2003

AbstractThe reaction of allyl cations and 1,3‐dienes affords seven‐, five‐, and six ‐membered rings as well as products of electrophilic substitution and linear 1:1‐adducts. In this review article, preparative and mechanistic advances are summarized with special emphasis on the synthesis of seven‐membered carbocycles. For the first time, a comprehensive mechanistic description is presented: Three classes A, B, and C correlate product type and stereochemistry with the nucleophilicity of the diene, the electrophilicity of the allyl cation intermediate, and the donor capacity of the group Y attached to the central carbon of the allylic moiety. The problem “allylic resonance versus nucleophilic participation of Y” is discussed and experimental evidence is adduced for some participation of Y as a function of its nucleophilicity. For cyclopentenyl cations, enhanced charge separation and electrophilicity are postulated, even when Y is a good donor, due to the structurally enforced polarity of the π‐allyl system.
Phospholipids as Functional Constituents of Biomembranes
Authors: Eibl Hansjörg 
Published: December 2003

AbstractThis article describes new methods for the synthesis of biologically active phospholipids. The physical properties of such compounds are directly related to their chemical structure, the position of the substituents esterified with glycerol not only influencing the physical properties but also the biological function of the phospholipids. Phase transitions can be induced by temperature changes and—in biological systems—by changes in the surface charge or the degree of protonation. In model studies, the properties of lipid phases differ sufficiently to influence and control biological membrane processes. Alkyl glycerides can modify the properties of biological membranes quickly and reversibly to increase the permeation of active compounds. An important example is the improved transport of cytostatic drugs across the blood‐brain barrier. Knowledge about the substrate specificity of enzymes that metabolize phospholipids allows the synthesis of tailored cytotoxic phospholipids which selectively accumulate in malignant tissues. Thus, the interplay of chemical synthesis and investigations of physical structure lays a foundation for the understanding of simple membrane processes on a molecular level, and the experience gained with such model systems can, in turn, be used to influence natural membranes, such as those of the blood‐brain barrier or of tumors, in a directed way.