bluuebunny/crossref_metadata_2025_split huggingface dataset:
Organic Synthesis Using Metal‐Mediated Metathesis Reactions
Authors: Kissling Rebecca M. , Nolan Steven P. 
Published: December 2011

Abstract
Olefin metathesis is an established reaction, yet it is still growing and diversifying at a remarkable rate. Since 2000, there has been notable progress in a number of areas, especially the development of new catalysts, many of which have N‐heterocyclic carbenes modifying ruthenium. These include phosphine‐free ruthenium catalysts that broaden the scope of efficient ruthenium‐catalyzed olefin metathesis, as well as catalysts with N‐heterocyclic carbenes and electron‐poor phosphines having turnover frequencies >100‐fold faster than the original Grubbs catalyst. In concert with this, some excellent mechanistic experiments and theoretical work have better elucidated the structure‐reactivity relationship and subtle but important points about mechanism relative rates of phosphine. Association, dissociation, and formation of the metallacyclobutane of the ruthenium‐catalyzed reactions are leading the way to further improvements in ruthenium catalysts.

Many methodological applications have also been developed, including improvements in the scope of hetereocycle and macrocycle formation. Cross metathesis (CM) has also undergone a transformation to a high yielding and stereoselective reaction that can be performed with predictable outcomes of yield and alkene stereochemistry. Great strides have been made in asymmetric olefin metathesis reactions, especially desymmetrization and kinetic resolution, with the majority of the results reported using molybdenum‐based catalysts with
C
2
‐symmetric chiral bisaryloxy based ligands. In addition, successful ruthenium‐based catalysts with
C
2
‐ and
C
1
‐symmetric ligands have been reported. Numerous reports of Tandem and sequential olefin metathesis reactions have been published, often in one‐pot, and sometimes utilizing the same metal complex for multiple operations, like ring closure/hydrogenation. A number of examples of tandem reactions utilizing a palladium catalyst and ruthenium‐catalyzed olefin metathesis have also been reported as very efficient routes to desirable organic building blocks.

One of the areas that exploited olefin metathesis is natural product synthesis. There are an ever increasing number of reports that cite olefin metathesis as a key, often step saving, reaction in the successful completion of target molecules by ring closing or cross metathesis. The synthetic advantages the olefin metathesis reaction have also been employed by materials and polymer chemists as part of design strategies for constructing well‐defined polymers, substrates for combinatorial chemistry, and metal‐containing rings.
The olefin metathesis catalysts have been attached to a variety of supports for the purpose of recycling. Many groups have examined methods for tethering both molybdenum and ruthenium‐based catalysts through reversibly coordinating ligands, the alkylidene and the backbone of nonlabile ligands, with reports of high efficiency recycling of up to 10 times.
Organic Synthesis Using Metal‐Mediated Coupling Reactions
Authors: Goodson Felix E. , Cichowicz Melissa B. 
Published: December 2011

Abstract
This article provides an overview of the cross‐coupling protocols most commonly used in organic synthesis. Particular emphasis is placed upon topics likely to be of interest to the inorganic chemist, namely, history, catalyst development, and mechanistic studies. While not a comprehensive review, this treatment is intended to provide the reader with a summary of some successful catalyst design strategies, methodological improvements, and mechanistic insights that have been achieved over the past 10 years.
Porous Inorganic Materials
Authors: Wang Xiqing , Bu Xianhui , Feng Pingyun 
Published: December 2011

AbstractPorous inorganic materials cover a range of solids, both oxides and nonoxides, crystalline and amorphous, that have a pore size extending from about 3 Å to over 500 Å. Crystalline microporous materials such as zeolites have been known for over 200 years, and the research in the past decade has extended types of microporous materials from traditional oxides to chalcogenides and metal–organic frameworks. Efforts aimed toward developing new microporous materials that integrate uniform microporosity with other functionality have also led to promising results.Periodically ordered mesoporous materials are a recent addition to the family of ordered inorganic porous materials. They can be made in the presence of organized assemblies of organic molecules (e.g. amines, cationic, anionic, or nonionic surfactants) or polymers (e.g. amphiphilic block copolymers). Micellar solutions, lyotropic liquid crystals, and microemulsions can all serve as structure‐directing agents during the cocondensation of inorganic precursors with organic species. A number of synthetic pathways have been developed for the preparation of mesoporous solids in a variety of chemical compositions including silica, organosilica, transition metal oxides, chalcogenides, and even elemental forms such as carbon and platinum. Much progress has also been made in the control of macroscopic morphologies (e.g. films, fibers, monoliths, and spheres). The pore geometry is closely related to the nature of the organic assemblies and other synthetic parameters and can be controlled to a certain degree to allow the synthesis of mesoporous materials with the desirable architecture and properties.The past decade has also witnessed a rapid development in the synthesis of ordered macroporous materials and porous materials that are ordered at multiple‐length scales. Commonly used templates for the control of the macroscopic ordering include colloidal crystals such as latex or silica spheres and emulsion droplets. With the availability of a variety of inorganic porous materials, numerous applications are awaiting the exploration of materials researchers.
Self‐Assembled Inorganic Architectures
Authors: Bera Jitendra K. , Bacsa John , Dunbar Kim R. 
Published: December 2011

Abstract
The field of inorganic chemistry is witnessing an enormous growth period in the area of molecular self‐assembly. This review highlights key advances in this area with an emphasis on novel structures and the dynamic nature of inorganic self‐assembly reactions. Multidentate N‐heterocylic, cyanide, and carboxylate ligands are discussed in detail with respect to their use in the design of discrete structures, including molecular triangles, squares, pentagon, cubes, as well as polyhedra, oligomers, and polymers. Inorganic structures that employ metal–coordination and hydrogen bonds are also highlighted. The examples described herein illustrate the fact that the available binding sites and the topicity of the ligands along with the coordination requirements of metal ions are the key elements for building desired architectures. The role of intrinsic factors such as geometrical preferences of the metal ion as well as extrinsic factors such as the presence of a template in stabilizing a particular product are discussed. Recent progress in the rational design of functional materials vis‐à‐vis the manipulation of supramolecular chemistry is also covered in brief.
Hydrogen Bonding & Dihydrogen Bonding
Authors: Crabtree Robert H. 
Published: December 2011

AbstractThe review begins with the historical development of the area, notably Pauling's contribution. The current interest is in part related to the rise of supramolecular chemistry and molecular recognition, as well as the significance of hydrogen bonding in biology and biochemistry. Strong and weak cases are distinguished. A relationship with hypervalency is proposed, in which the bridging proton of a FHF anion is considered as hypervalent hydrogen. Dihydrogen bonding is considered the latest hydrogen bond type. Structural and spectroscopic aspects are discussed, together with applications. Hydrogen bonding in metal complexes is covered together with the distinction between hydrogen bonding and sigma complexation.
Carbene Complexes
Authors: Crabtree Robert H. 
Published: December 2011

AbstractThe synthesis, structure, reactions, and applications of carbenes are discussed. Fischer and Schrock carbenes are distinguished. N‐heterocyclic carbenes (NHCs) are considered as a class of Fischer carbenes with promise as spectator ligands in homogeneous catalysis. Nucleophilic attack on carbonyls and alpha elimination are noted as leading pathways leading to Fischer and Schrock carbenes, respectively. Criteria are discussed for characterization of carbenes, notably nuclear magnetic resonance (NMR) spectroscopy. The Grubbs metathesis catalyst and alkene metathesis catalysis are also mentioned. Bridging carbenes and carbynes are briefly considered.
Low Oxidation State Main Group
Authors: Macdonald Charles L. B. , Ellis Bobby D. 
Published: December 2011

AbstractThe synthesis and chemistry of compounds containing groups 13–15 elements in unusually low oxidation states is presented. In general, the oxidation state of an element influences the reactivity of the compounds in which the atom is found. For the main group elements, compounds containing elements in lower than usual oxidation states exhibit significantly different structural features, modes of bonding, and chemistry than is observed for compounds containing the element in a more typical oxidation state. The elements of the s‐block do not form low oxidation state compounds and the elements of groups 16–18 are generally found in the lowest available oxidation state. Thus, this article provides an overview of the following classes of low‐valent main group species: the chemistry of group 13 elements in the +1 and +2 oxidation states, the chemistry of group 14 elements in the 0 oxidation state, and the chemistry of the group 15 elements in oxidation states lower than +3. Numerous exemplary modes of reactivity are presented and the utility of some low oxidation state compounds as catalysts or precursors to materials is acknowledged.
Transition Metal Complexes with Bulky Allyl Ligands
Authors: Hanusa Timothy P. , Carlson Christin N. 
Published: December 2011

AbstractThe allyl anion (C3H5−) is often found in combination with other ligands in organometallic complexes. Its compact size, however, means that compounds in which it is the only or principal type of ligand are frequently coordinatively unsaturated and prone to decomposition. Sterically bulky substituents (e.g. – SiMe3) placed on the allyl group will increase its effective size, dramatically enhancing the thermal, and in some cases oxidative, stability of the associated metal complexes. Solubility in nonpolar solvents such as aromatic hydrocarbons and alkanes is also improved. Electron‐deficient monomeric first row transition metal allyl complexes (e.g. [π‐(SiMe3)2C3H3]2M; M = Cr, Fe, Co) have been synthesized that have no (C3H5)2M counterparts. New varieties of early transition metal and f‐element complexes have been made with bulky allyl ligands, some of which are active polymerization catalysts. Research in this area has markedly expanded the range of metals, structural types, and associated reactions that can be incorporated into metal allyl chemistry.
Subvalent Compounds
Authors: Brothers Penelope J. 
Published: December 2011

Abstract
Subvalent compounds are those in which a main group element occurs in an oxidation state lower than its normal group oxidation state. Traditionally, these have been identified in solid‐state inorganic phases, but more recently there have been major advances in the preparation of stable, molecular compounds containing subvalent main group elements. This has occurred in some cases through the use of specially designed ligands able to stabilize low oxidation state species through electronic stabilization or steric protection using bulky substituents. Ingenious synthetic routes such as the preparation of solutions in organic solvents of metastable aluminum(I) and gallium(I) halides have allowed access to other novel species. Apart from a relatively small number of types of mononuclear complexes, most subvalent molecular compounds involve homoatomic element–element bonds in the form of rings, chains, and clusters. Many of these have unusual structural and electronic properties that challenge established, classical ideas of bonding and electronic structure. This discussion focuses on recent advances in the structure and chemistry of molecular subvalent compounds, with an emphasis on the groups 13 and 14 elements. In addition to mononuclear and simple homonuclear single‐bonded compounds, several classes of cluster compounds are examined, including electron‐precise, electron‐rich, and electron‐deficient clusters. The latter include the Zintl ions. A very new class of aluminum and gallium metalloid clusters containing metal–metal bonds unsupported by ligands represents species on the pathway to formation of the bulk metal. An area in which exciting developments have taken place in the last decade encompasses subvalent compounds that are heavier main group element analogs of alkenes and alkynes, and significant structural features and new bonding models for these are discussed.
Metal Nanoparticles, Synthesis of
Authors: Schmid Günter 
Published: December 2011

Abstract
The successful synthesis of metal nanoparticles decisively depends on sufficient stabilisation by protecting materials. This can be reached either by electrostatic repulsion of charged species or by covering the surface atoms with polymers, surfactants, or especially ligand molecules binding to the particles via covalent bonds. Noble metals are in focus, since their salts or complexes can easily be reduced to the oxidation state 0 and the sensitivity towards oxygen is reduced or even avoided like in the case of gold. Nevertheless, nanoparticles of less noble metals can be prepared. Above all, there is an increasing need to get monodispersed particles, since their properties depend on size and shape. There exist so‐called physical methods to generate metal atoms from bulk metals that are then allowed to coalesce to nanoparticles. High temperatures or laser ablations are examples. Chemically based procedures use in any case stabilizing agencies. Among numerous methods, salt reduction dominates. Thermal decomposition of appropriate precursor complexes and soft ligand removal from organometallics have become known as alternative routes. Photolytic and radiolytic techniques exist, but do not play important roles. The synthesis of magnetic metal nanoparticles is of increasing interest with respect to applications. The syntheses mainly follow recipes known from noble metals. Fe, Co, Ni as well as magnetic bimetallic alloy‐like nanoparticles are available. The magnetic characteristics of nanoparticles again depend decisively on size, structure, and shape, even more than in case of the nonmagnetic species. Therefore, synthetic procedures resulting in uniform particles are of great importance.
Carbon: Nanotubes
Authors: Baskaran Durairaj 
Published: December 2011

Abstract
A brief introduction to carbon nanotubes with basic structural classification, synthesis, properties, and surface modification is presented. The growth process of carbon nanotubes and the role of metals catalyst in the arc‐discharge, the laser‐vaporization, and the chemical vapor deposition (CVD) techniques are discussed. The synthesis of aligned carbon nanotubes in a preferred orientation from various substrates and the formation of branched carbon nanotubes are unique features of the CVD technique. The method of purification of carbon nanotubes is chosen on the basis of the amount of catalyst impurities and amorphous carbon present in them that are dependent on the techniques used to produce carbon nanotubes. Oxidative purification methods and the introduction of carboxylic acid on the surface of carbon nanotubes have been described. Optical, electrical, and mechanical properties of carbon nantubes have been highlighted. An overview of the surface modification of carbon nanotubes with covalent and noncovalent chemistry to enhance the dispersion and dissolution properties of carbon nantotubes and the problem associated with size, length, and the functional groups distribution affecting the solution properties of carbon nanotubes have been discussed.
High‐Energy Electron Diffraction
Authors: Zuo Jian‐Min 
Published: December 2011

AbstractHigh‐energy electrons have very short wavelengths associated with particle waves and electron diffraction is used to probe the atomic structure of both inorganic and organic materials. Electrons have a large scattering cross section and can be focused into small probes by magnetic lenses. This makes electron diffraction very useful for studying “small” crystals, surfaces, or material's microstructure. The principles and the modern aspects of electron diffraction are described here with the intention to provide an introduction that both the novice and the expert will find useful as a guide for electron diffraction. The chapter starts with an introduction to different electron diffraction techniques. This is followed by the background theories which are useful for the interpretation of diffraction patterns. Experimental procedures are described at the end of the technical background. The applications section has a large collection of examples from relatively straightforward tasks to more advanced ones that are under development for their promises. Experimental details are provided when it is appropriate to give some idea of what it takes to do electron diffraction.
High Resolution Electron Energy‐Loss Spectroscopy
Authors: Soriaga Manuel P. , Chen Xiaole , Li Ding , Stickney John L. 
Published: December 2011

AbstractThe determination of the identity and structure of molecular species present in no more than monolayer quantities at solid surfaces is one of the more difficult tasks in interfacial science. In this regard, vibrational spectroscopy is an invaluable technique; in the evaluation of the molecular integrity of surface‐bound compounds, it has few equals. Optical methods such as infrared spectroscopy, while rather uncomplicated for bulk materials, lack the high sensitivity needed for most surface species due to minuscule molecular amounts. A much more responsive alternative is based on the use of low‐energy electrons to interact with the molecular oscillators on the surface. If inelastic interactions occur, the energy of the backscattered electrons will be lower than that of the incident electrons, and the energy loss will correspond to a vibrational‐mode frequency. The present article briefly describes the fundamental principles of and instrumental considerations in high‐resolution electron energy‐loss spectroscopy (HREELS), and cites seminal applications in the study of the adsorption of organic and inorganic molecules at metal and semiconductor surfaces. A limited list of HREELS work published since the turn of the century is added in the last section.
Magnetic Circular Dichroism (
MCD
) Spectroscopy
Authors: Mack John , Stillman Martin J. 
Published: December 2011

Abstract
Magnetic circular dichroism (MCD) spectroscopy provides information about the spin and orbital angular momenta associated with ground and excited electronic states. This can provide the key to understanding the optical spectroscopy of high symmetry ions and complexes, which provides an important insight into the electronic structure. MCD spectra contain the same set of spectral bands as the corresponding electronic absorption spectrum, with significantly different band morphologies due to the effect of the applied magnetic field and the use of a differential absorbance intensity scale.

MCD spectra are recorded by mounting a superconducting magnet (
B
≈ 0–11 T), an electromagnet (
B
≈ 0–1 T), or a permanent magnet into the sample compartment of a CD spectrometer with the field applied parallel to the axis of light propagation. Parallel applied fields are often referred to as the Faraday magnet alignment, since it formed the basis of Faraday's pioneering experiments in which plane polarized beams of light were found to be rotated during transmission through certain substances, due to the differential absorbance of left circularly polarized (lcp) and right circularly polarized (rcp) light. The Faraday 𝒜

1

, ℬ

0

, and 𝒞

0

terms form the basis for the analysis of MCD spectra based on the Zeeman splitting of the absorption bands for lcp and rcp light, the field‐induced mixing of zero‐field states, and the Zeeman splitting‐based ground state population adjustment, respectively.
Mass Spectrometry in Inorganic and Bioinorganic Chemistry
Authors: Becker Johanna Sabine , Becker Julia Susanne 
Published: December 2011

AbstractMass spectrometry (MS) in inorganic and bioinorganic chemistry has been established using sensitive analytical techniques in quite different application fields: the determination of major, minor, and trace element concentrations; for the characterization of surfaces; for precise and accurate isotope ratio measurements; and for the structural analysis of organic and bioorganic compounds. The review gives an overview on different mass spectrometric techniques and their applications
Microwave Rotational Spectroscopy
Authors: Xu Yunjie , Jäger Wolfgang 
Published: December 2011

AbstractSince its inception in 1934, microwave rotational spectroscopy has provided some of the most accurate data for numerous small to medium sized molecules, including structural parameters, force field parameters, and electronic charge distributions. We give a very brief review of the history of microwave spectroscopy, leading up to the most recent developments, that is, instruments that use Fourier transform techniques. Since these Fourier transform microwave spectrometers are not commercially available, a brief discussion about their general design is given. Analyses of the recorded rotational spectra can yield a number of spectroscopic parameters, depending on the molecular symmetry and the various angular momenta present, such as nuclear spins and electronic momenta. The physical significance of the more common spectroscopic parameters, such as rotational constants, centrifugal distortion constants, nuclear quadrupole coupling constants, etc. is given. We also indicate how these parameters can be used to characterize the molecule in terms of, for example, structural parameters, dynamical behavior, and bond character. The remainder of the article is devoted to case studies. These include the discovery of covalent bonds involving the noble gas atom argon, structural characterization of organometallic compounds, such as ferrocenes, bonding in diatomic transition metal‐containing compounds, a description of laboratory studies of molecules which are of atmospheric and astrophysical interest, and studies of weakly bound complexes with relevance to inorganic chemistry.