Chemistry - A European Journal

Cover image for Vol. 9 Issue 10

May 23, 2003

Volume 9, Issue 10

Pages 2133–2384

    1. Cover Picture: Structure–Nucleophilicity Relationships for Enamines (Chem. Eur. J. 10/2003) (page 2133)

      Bernhard Kempf, Nathalie Hampel, Armin R. Ofial and Herbert Mayr

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200390220

    2. Supercritical Fluid Synthesis of Metal and Semiconductor Nanomaterials (pages 2144–2150)

      Justin D. Holmes, Daniel M. Lyons and Kirk J. Ziegler

      Version of Record online: 22 APR 2003 | DOI: 10.1002/chem.200204521

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      Physical and economic constraints are expected to limit the continued miniaturisation of electronic and optical devices from current lithographic methods. In response, a number of research groups are developing supercritical fluid methodologies to synthesise “building blocks” of nanomaterials for “bottom-up” assembly techniques. This concepts paper highlights some of the recent advances in the synthesis of nanoparticles and nanowires using supercritical fluids the inclusion of nanowires in mesoporous materials, such as illustrated here.

    3. The First Linear Multiphosphazene Having Five Different Types of Side Groups and Its Use as the Core of a Dendrimeric Species (pages 2151–2159)

      Germinal Magro, Bruno Donnadieu, Anne-Marie Caminade and Jean-Pierre Majoral

      Version of Record online: 22 APR 2003 | DOI: 10.1002/chem.200204630

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      A butterfly? No, two dendrons linked to the first linear tetraphosphazene that contains four different types of functional side groups (see picture). The step-by-step synthesis of this compound is described, as well as a series of small, functionalized oligophosphazenes. A 31P NMR study of this series suggests a partial delocalization of the inorganic polyphosphazene backbone.

    4. Organized Nanostructured Complexes of Inorganic Clusters and Surfactants That Exhibit Thermal Solid-State Transformations (pages 2160–2166)

      Franck Camerel, Markus Antonietti and Charl F. J. Faul

      Version of Record online: 22 APR 2003 | DOI: 10.1002/chem.200204528

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      Nanostructured organic/inorganic hybrid materials with switchable structure were produced by the ionic self-assembly (ISA) route. The schematic representation shows the thermal solid-state transformations for the switchable [Ni3P3S12]3−/DiC12DA complex.

    5. Organic Reactions and Nanoparticle Preparation in CO2-Induced Water/P104/p-Xylene Microemulsions (pages 2167–2172)

      Rui Zhang, Jun Liu, Jun He, Buxing Han, Weize Wu, Tao Jiang, Zhimin Liu and Jimin Du

      Version of Record online: 22 APR 2003 | DOI: 10.1002/chem.200204496

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      CO2-induced microemulsions of (EO)27(PO)61(EO)27/p-xylene/CO2/H2O have been used to synthesize Au nanoparticles by the reduction of HAuCl4 with KBH4. The figure shows the UV-visible spectrum of the microemulsion containing Au nanoparticles. The peak at 525 nm is characteristic of Au particles larger than 3 nm. The recovery of the Au nanoparticles from the microemulsion can be easily accomplished by venting of CO2, while the surfactant remains in the organic phase.

    6. Definitive Ab Initio Studies of Model SN2 Reactions CH3X+F (X=F, Cl, CN, OH, SH, NH2, PH2) (pages 2173–2192)

      Jason M. Gonzales, Chaeho Pak, R. Sidney Cox, Wesley D. Allen, Henry F. Schaefer III, Attila G. Császár and György Tarczay

      Version of Record online: 22 APR 2003 | DOI: 10.1002/chem.200204408

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      The energetic and structural characteristics of SN2 reactions have long been of interest to chemists. It is well known that these reactions exhibit double well potentials (see figure). We present detailed energetic analyses of the stationary points associated with seven of these reactions, computing high-level energetics with the focal point procedure, and decomposing these energies into quasi-physical components using several decomposition schemes. Several interesting trends are manifested, including the lack of backside complexes when acidic hydrogens are present.

    7. The Structure of the Sugar Residue in Glycated Human Serum Albumin and Its Molecular Recognition by Phenylboronate (pages 2193–2199)

      Jan Rohovec, Thomas Maschmeyer, Silvio Aime and Joop A. Peters

      Version of Record online: 22 APR 2003 | DOI: 10.1002/chem.200204632

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      A measure of mid-term blood-sugar concentrations, useful for the management of diabetes, can be derived from quantification of the extent of glycation of human serum albumin (HSA). After Amadori rearrangement, the sugar moieties in glycated HSA occur as an equilibrium of the β-pyranose (59 %), α-furanose (19 %) and β-furanose (24 %) anomers. The open form is not observed. The β-furanose anomer is selectively recognised by phenylboronate, as shown.

    8. Synthesis and Reactions of Terminal Osmium and Ruthenium Complexed Phosphinidenes [(η6-Ar)(L)M[DOUBLE BOND]PMes*] (pages 2200–2208)

      Arjan T. Termaten, Tom Nijbacker, Marius Schakel, Martin Lutz, Anthony L. Spek and Koop Lammertsma

      Version of Record online: 22 APR 2003 | DOI: 10.1002/chem.200204582

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      Novel, highly reactive Ru and Os phosphinidene complexes [(η6-Ar)M[DOUBLE BOND]PMes*], which can be effectively stabilized by appropriate ligands (L = PR3, CO, and RNC), have been prepared by dehydrohalogenation of primary phosphine complexes [(η6-Ar)Cl2M(PH2Mes*)]. The transient Ru species [(η6-C6H6)Ru[DOUBLE BOND]PMes*] exhibits intriguing C[BOND]H bond activation upon dimerization or reaction with but-2-yne.

    9. Structure–Nucleophilicity Relationships for Enamines (pages 2209–2218)

      Bernhard Kempf, Nathalie Hampel, Armin R. Ofial and Herbert Mayr

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200204666

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      Enamines are commonly characterized as “strong nucleophiles”. Kinetic investigations of the reactions of 28 enamines and related compounds with benzhydrylium ions show that their reactivities span over ten orders of magnitude corresponding to relative reactions times of 1 min versus 20 000 years. Their reactivities are compared with those of other carbon nucleophiles.

    10. Low-Temperature IR and NMR Studies of the Interaction of Group 8 Metal Dihydrides with Alcohols (pages 2219–2228)

      Evgenii I. Gutsul, Natalia V. Belkova, Maria S. Sverdlov, Lina M. Epstein, Elena S. Shubina, Vladimir I. Bakhmutov, Tatiana N. Gribanova, Ruslan M. Minyaev, Claudio Bianchini, Maurizio Peruzzini and Fabrizio Zanobini

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200204510

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      The reactions of the octahedral dihydrido complexes [MH2(PP3)] [M = Fe, Ru, Os; PP3=P(CH2CH2PPh2)3] with a variety of weak ROH acids have been studied (see scheme) by IR and NMR spectroscopic methods in either CH2Cl2 or THF. The study has allowed the determination of the spectral and thermodynamic properties associated with the formation of dihydrogen bonds (DHB) between the terminal hydrides and the OH group.

    11. Synthesis and Characterization of Ion-Exchangeable Titanate Nanotubes (pages 2229–2238)

      Xiaoming Sun and Yadong Li

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200204394

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      Titanate nanotubes were synthesized by using a simple hydrothermal method, followed by washing with water and dispersion with alcohol (see picture). Ion substitution with transition-metal ions provided an opportunity to prepare complex transition-metal oxide nanotubes with increased BET surface areas. These nanotubes are ideal materials for heterogeneous catalysis or catalysts support, as well as candidates for host–guest chemistry, ion exchange, and absorbents.

    12. Formation of Two Isomeric closo-[(η5-C5H5)FePC2B8H10] Phosphadicarbaborane Analogues of Ferrocene via Isolable η1-Bonded Complexes of the [7-{(η5-C5H5)Fe(CO)2}-(η1-nido-PC2B8H10)] Type (pages 2239–2244)

      Bohumil Štíbr, Josef Holub, Mario Bakardjiev, Ivan Pavlík, Oleg L. Tok, Ivana Císařová, Bernd Wrackmeyer and Max Herberhold

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200204704

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      The first two phosphadicarbaborane analogues of ferrocene with a closo-[(η5-C5H5)FePC2B8H10] structure (see picture for one isomer) have been isolated by complexation of nido-[7,8,9-PC2B8H11] with [{CpFe(CO)2}2]. The reaction proceeds via two isolable η1-bonded nido intermediates of general constitution [7-{(η5-C5H5)Fe(CO)2}(η1-PC2B8H10)].

    13. Thioformaldehyde S-Methylide and Thioacetone S-Methylide: An Ab Initio MO Study of Structure and Cycloaddition Reactivity (pages 2245–2255)

      Reiner Sustmann, Willi Sicking and Rolf Huisgen

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200204658

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      Competing concerted and biradical pathways occur when thiocarbonyl S-ylides react with thiocarbonyl compounds to form cycloadducts. The mechanism of this reaction and the transition structures (see picture) have been studied by ab initio calculations.

    14. 1,3-Dithiolanes from Cycloadditions of Alicyclic and Aliphatic Thiocarbonyl Ylides with Thiones: Regioselectivity (pages 2256–2263)

      Rolf Huisgen, Grzegorz Mloston, Kurt Polborn and Reiner Sustmann

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200204659

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      A fascinating regioselectivity problem arises in 1,3-cycloadditions between thiocarbonyl ylides A and thiones B. Only 2,4-substituted 1,3-dithiolanes C are produced when R2 and R′2 are alicyclic or aliphatic, whereas systems with aromatic R2 and R′2 exclusively furnish the 4,5-substituted D. TS calculations (preceding paper) showed competition between a concerted and a biradical mechanism. The experience with aliphatic and spirocyclic systems is described here.

    15. Novel Conformationally Locked Inositols: From Aromatics to Annulated Cyclitols (pages 2264–2272)

      Goverdhan Mehta, Ramesh S. Senaiar and Mrinal K. Bera

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200204650

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      A new family of ring-annulated inositols with “locked” conformations (see scheme) has been designed to deliver a range of these biologically important entities in “unnatural conformations” while retaining their “natural configurations”. The simple tool of trans ring fusion has been used to lock the conformation of the annulated inositols. Short, simple syntheses of a range of these novel cyclitols have been achieved from readily available aromatic precursors such as tetralin and indane.

    16. Unusual Coupling Reactions of Aldehydes and Alkynes: A Novel Preparation of Substituted Phthalic Acid Derivatives by Automated Synthesis (pages 2273–2281)

      Axel Jacobi von Wangelin, Helfried Neumann, Dirk Gördes, Stefan Klaus, Haijun Jiao, Anke Spannenberg, Thomas Krüger, Christian Wendler, Kerstin Thurow, Norbert Stoll and Matthias Beller

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200204668

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      A new domino condensation –cycloaddition–elimination sequence for the synthesis of substituted phthalic esters has been developed and subjected to parallelized and automated. The 60-well Syncore reactor used for the synthesis is depicted with the reaction scheme.

    17. meso-Substituted Aromatic 34π Core-Modified Octaphyrins: Syntheses, Characterization and Anion Binding Properties (pages 2282–2290)

      Venkataramanarao G. Anand, Sundararaman Venkatraman, Harapriya Rath, Tavarekere K. Chandrashekar, Weijie Teng and Karin Ruhlandt-Senge

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200204537

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      Syntheses of new modified aromatic 34π planar octaphyrins has been achieved through an acid-catalyzed oxidative coupling reaction of tetrapyrrane. Octaphyrins bind TFA anions in their protonated form through electrostatic N-H-O and non-electrostatic C-H-O interactions such as depicted.

    18. One-Step Preparation, Structural Assignment, and Xray Study of 2,2-Di-n-butyl- and 2,2-Diphenyl-6-aza-1,3-dioxa-2-stannabenzocyclononen-4-ones Derived from Amino Acids (pages 2291–2306)

      Hiram I. Beltrán, Luis S. Zamudio-Rivera, Teresa Mancilla, Rosa Santillan and Norberto Farfán

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200204260

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      Imino acid derivatives with a transannular N[RIGHTWARDS ARROW]Sn bond and a tridentate ligand have been prepared by a one-step reaction. In all cases, the 119Sn NMR chemical shifts, as well as the 1J(119Sn,13C) and 1J(117Sn,13C) coupling constants, are indicative of pentacoordinated tin atoms in solution. The crystal structures of nine compounds reveal a distorted trigonal-bipyramidal (TBP) geometry around the tin atom.

    19. Role of the Coordination of the Azido Bridge in the Magnetic Coupling of Copper(II) Binuclear Complexes (pages 2307–2315)

      Jesús Cabrero, Coen de Graaf, Esther Bordas, Rosa Caballol and Jean-Paul Malrieu

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200204167

      The difference dedicated configuration interaction (DDCI) method is applied to calculate the exchange coupling constant and the spin densities in binuclear CuII azido-bridged complexes with end-to-end and end-on coordination. An analysis of the physical effects that produce antiferromagnetic or ferromagnetic behaviour of these compounds is given.

    20. The Magnetic Properties of Myoglobin as Studied by NMR Spectroscopy (pages 2316–2322)

      Ivano Bertini, Claudio Luchinat, Paola Turano, Giuseppe Battaini and Luigi Casella

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200204562

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      The metal magnetic susceptibility tensor of myoglobin in water at room temperature was determined by NMR methods. The isotropic susceptibility is found to be sizably higher than previously believed, and the principal axes of the tensor are found oriented in an unprecedented way for high-spin iron(II) heme systems. These findings provide new insight on the electronic structure of myoglobin and of other high-spin iron(II) heme proteins like cytochrome c′ (see scheme).

    21. η6-Mesityl,η1-Imidazolinylidene–Carbene–Ruthenium(II) Complexes: Catalytic Activity of their Allenylidene Derivatives in Alkene Metathesis and Cycloisomerisation Reactions (pages 2323–2330)

      Bekir Çetinkaya, Serpil Demir, Ismail Özdemir, Loïc Toupet, David Sémeril, Christian Bruneau and Pierre H. Dixneuf

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200204533

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      Mixed heterocyclic carbene–arene–ruthenium complexes have been made from 1,3-imidazolinium salts with a 2,4,6-trimethylbenzyl N substituent, as per the scheme. They easily give unstable allenylidene–ruthenium species that are active for alkene ring-closing metathesis.

    22. Self-Assembled Monolayers of Novel Surface-Bound Dendrons: Peripheral Structure Determines Surface Organization (pages 2331–2336)

      Bin Dong, Fengwei Huo, Lu Zhang, Xunyu Yang, Zhiqiang Wang, Xi Zhang, Shaoyun Gong and Jinghong Li

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200204483

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      Slight modifications to the structure of a surface-bound dendron have a major influence on the organization of the structures and their behavior. For example, introduction of heptane chains appears to enhance the interaction between the symmetrical backbones, leading to the formation of stripes (see picture), whereas the introduction of oligo(ethylene oxide) chains appears to weaken the interaction resulting in a homogeneous structure.

    23. Molecular Nitrides Containing Group 4 and 5 Metals: Single and Double Azatitanocubanes (pages 2337–2346)

      Angel Abarca, Mikhail V. Galakhov, José Gracia, Avelino Martín, Miguel Mena, Josep-M. Poblet, José P. Sarasa and Carlos Yélamos

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200204593

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      Single and double-cube molecular nitrido complexes can be tailor-made from [{Ti(η5-C5Me5)(μ-NH)}3(μ3-N)] and imido/amido derivatives of Group 4 and 5 metals (see picture). Their structures have been studied by NMR spectroscopy, X-ray diffraction, and density functional theory calculations.

    24. A Non-Radical Mechanism for Methane Hydroxylation at the Diiron Active Site of Soluble Methane Monooxygenase (pages 2347–2358)

      Kazunari Yoshizawa and Takashi Yumura

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200204269

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      A non-radical mechanism for the conversion of methane into methanol by soluble methane monooxygenase (sMMO), the active site of which involves a coordinatively unsaturated diiron active center, is proposed (see scheme). This mechanism is essentially identical to that of the methane—-methanol conversion by the bare FeO+ complex and relevant transition-metal–oxo complexes in the gas phase.

    25. Direct Catalytic Asymmetric Mannich Reactions of Malonates and β-Keto Esters (pages 2359–2367)

      Mauro Marigo, Anne Kjærsgaard, Karsten Juhl, Nicholas Gathergood and Karl Anker Jørgensen

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200204679

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      Highly functionalized optically active compounds can be obtained with an activated α-imino ester in direct Mannich reactions catalyzed by chiral bisoxazoline copper(II) complexes malonates and β-ketoesters such as depicted.

    26. A New Strategy for the Design of Water-Soluble Synthetic Receptors: Specific Recognition of DNA Intercalators and Diamines. (pages 2368–2380)

      Kenji Wada, Tadashi Mizutani, Hideki Matsuoka and Susumu Kitagawa

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200204481

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      Conformational changes induced by hydrophobic and electrostatic interactions result in tight binding of DNA intercalators by water-soluble bisporphyrin receptors, as shown in the scheme.

    27. Preview: Chem. Eur. J. 10/2003 (page 2384)

      Version of Record online: 16 MAY 2003 | DOI: 10.1002/chem.200390222