bluuebunny/crossref_metadata_2025 huggingface dataset:
Electronic Structure of Solids
Authors: Cox P A
Published: November 2023

Modern inorganic chemistry is based firmly on the ideas of electronic structure which are provided by the quantum theory of atoms and molecules. The approach used by most chemists is necessarily very approximate, since although quite accurate quantum-mechanical calculations can now be performed on small molecules, the results of these are expressed in terms which are too sophisticated to extend easily to larger systems. Thus, inorganic and organic chemists tend to use the language of approximate molecular orbital theory, and to think in terms of simple models of the filled and empty orbitals of a molecule in order to interpret its structure and properties. This brief account of the electronic structure of solids follows the chemists' approach, and is rather different from the treatment normally given in textbooks on solids. Such books tend to be written by physicists for students of physics, and depend heavily on the properties of free electrons moving in a crystal. As a result, these accounts are somewhat uncongenial to the average chemist, both because they start from a point of view which is too mathematical, and because they stop short of describing the types of complex solid which are of current chemical interest. In the present treatment, solids are discussed using the same simple models, derived from linear combinations of atomic orbitals, as are used in molecular chemistry.
Space group representations
Authors: Altmann Simon L
Published: November 2023

We have obtained the Bloch functions ψK(r) in Chapter 5 as eigenfunctions of the translations (eqn 5–5.1) but their real importance stems from three properties of the N Bloch functions which correspond to the N internal points in the Brillouin zone (see § 5–5), where N is the number of primitive cells in the crystal. (i) They form bases for representations of the space group G. (ii) These bases are irreducible. (iii) These bases span all the irreducible bases of G. We shall go a long way in this chapter in establishing (i) and (ii) fairly decently, but (iii) is beyond our scope. In Chapter 7, however, we shall work out a simple example in which we shall be able to satisfy ourselves that these properties are all true. The treatment that we shall give in this and the following chapters will mostly be concerned with symmorphic space groups, but its extension for non-symmorphic ones is possible without major changes in the basic concepts which we shall discuss.
Leiden
Authors: Kipnis A Ya , Yavelov B E , Rowlinson J S
Published: November 2023

The first record of the forebears of the great Dutch physicist Johannes Diderik van der Waals is dated 20 April, 1639. On that day the birth of Michiel Bartholomeesz van der Waal from Brielle, then a little fort at the confluence of the Maas and Waal, was registered at Leiden Town Hall. His father Bartholomeus—not yet van der Waal—was born between 1580 and 1590, probably also in Brielle The name van der Waal seems, however, to suggest that the family came originally from the banks of the Waal, the southern arm of the lower Rhine, which flows into the sea close to Brielle.
The HBS teacher
Authors: Kipnis A Ya , Yavelov B E , Rowlinson J S
Published: November 2023

Two points of interest never failed to be mentioned by the nineteenth century guide-books to Deventer, ‘a clean and prosperous town’, as the omniscient Baedeker put it [J, p. 306]. These were, first, the famous Deventer koeken, or honey-cakes, which were sold all over the country and even exported to the East and West Indies and, secondly, the Deventer Athenaeum Jllustre which was founded as early as 1630.
Where porphyrins come from …
Authors: Milgrom Lionel R
Published: November 2023

It is difficult to imagine the earth as a young world devoid of all life. The famous Walt Disney cartoon Fantasia gives as good a picture as any of what our prebiotic planet must have been like. The scientific imagination has managed to add some bones to Hollywood’s speculations, in the form of experiments on mixtures of gases that are thought to have constituted the earth’s primordial atmosphere.
The effect of solvent-surf ace interactions on crystal growth and dissolution
Authors: Shimon L J W , Vaida M , Addadi L , Lahav M , Leiserowitz L
Published: November 2023

The effect of solvent on crystal growth and dissolution studied by two stereochemical strategies is described1. The first approach involved the growth of N-(E-cinnamoyl)-(S)-alanine from acetic acid and of three crystalline hydrates (asparagine-H2O, rhamnose-H2O and S-lysine-HC1-2H2O) in the presence of primary alcohols as 11tailor-made11 solvents. It was demonstrated that stereospecific adsorption of the tailor-made solvent at a particular face inhibits its growth. The second approach, concerned the growth and dissolution of hemihedral faces at the opposite ends of the polar axes of ( R,S)-alanine and (glycine in water, methanol and ethanol, one pole exposing carboxylate groups and the other amino groups. Relatively fast growth and dissolution at the carboxylate end in water was explained in terms of strong solvent binding at a subset of surface sites and solvent repulsion at the remaining sites, so allowing for easy access of solute at the latter unhydrated surface sites followed by expulsion of water at the former. The repetitive succession of these steps results in a 11relay11type mechanism of crystal growth.
Organic crystal chemistry in the 1990’s
Authors: Jones D W
Published: November 2023

In the final session of the Symposium, A. K lman (Hungary) chaired a round-table session in which J. Bernstein (Israel), R. Boese (F.R. Germany), L. Leiserowitz (Israel) and J. Lipkowski (Poland) voiced personal thoughts and predictions about the shape of organic crystal chemistry in the next few years. From these individual contributions, one could discern four ma-in themes, each raised or inferred by more than one speaker: (1) collaborative approaches in structural science; (2) use of accumulated crystallographic data; (3) emerging topics in crystal chemistry; and (4) exploitation of newer techniques.
The CCP4 package program
Authors: Evans P R
Published: November 2023

The CCP4 program suite is a collection of disparate programs covering most of the computations required for macromolecular crystallography. They have been collected and developed under the auspices of the Collaborative Computing Project number 4, in protein crystallography, supported by the UK Science & Engineering Research Council (SERC), and coordinated at the SERC Daresbury Laboratory. More recently, the collaboration on development of the suite has been extended to the whole of Europe under the auspices of the European Science Foundation Network for the European Association for Crystallography of Biological Macromolecules. Unlike many other packages, particularly for small molecule crystallography, the CCP4 suite is a set of separate programs which communicate via standard data files, rather than all operations being integrated into one huge program. This has some disadvantages in that is is less easy for programs to make decisions about what operation to do next (though this is seldom a problem in practice), and that the programs are less consistent with each other (though work is continuing to improve this). The advantage of this loose organization is that it is very easy to add new programs or to modify existing ones without upsetting other parts of the suite. Converting a program to use the standard CCP4 file formats is generally straightforward, and the philosophy of the collection has been to be inclusive, so that several programs may be available to do the same task. The components of the whole system are then a collection of programs using a standard subroutine library to access standard format files, and a set of procedures for the operating system to run each program. These procedures are available for VMS and Unix.
About the integration of direct and Patterson methods
Authors: Giocovazzo C
Published: November 2023

Information contained in a Patterson map can be incorporated with Direct Methods. Different types of information are considered .from the simplest one, i.e. the positional vector and the intensity of a Patterson peak,to more sophisticated kinds of prior information (i.e., the identification of related Patterson vectors,the identification of Harker peaks, etc.).The influence of each type of Patterson information on the statistical model is outlined .It is shown that in some cases restraints to the domains accessible to the primitive random variables are generated; in other cases correlation between the primitive random variables are created.
Maximum entropy as a common statistical basis for all phase determination methods
Authors: Bricogne G
Published: November 2023

A comprehensive Bayesian scheme aimed at integrating all methods of three-dimensional structure determination from diffraction measurements is outlined. It is first shown that all currently used sources of phase information can be represented and combined through a universal expression for the joint probability distribution of structure factors. This result is then used to derive likelihood functions capable of consulting experimental diffraction data originating not only from single crystals but also from powders, fibres and other specimens whose disorder causes intensity overlaps. Likelihood criteria obtained in this way are the key elements in a multisolution phasing strategy of very wide applicability.
Maximum entropy, likelihood, and the phase problem in single crystal and powder diffraction
Authors: Gilmore C J , Bricogne G
Published: November 2023

where p( · ) denotes probability. The three components of this equation are termed the posterior, the prior and the likelihood respectively. In a Bayesian approach to statistics one first defines one’s prior knowledge; likelihood is then used to consult the experimental data, and the two used to produced a posterior probability which reflects modifications to the prior which arise from the data. The posterior thus generated can be used as the new prior and the whole process repeated in a cyclical way.
A protein structure database
Authors: Murray-Rust P
Published: November 2023

As part of the UK SERC Protein Engineering Club, a database project was funded, whose aim was to coordinate the storage and searching of protein sequence and structure (ISIS). This chapter describes the BIPED database, where protein structures from the Brookhaven databank have been organised in relational mode. The database has been developed at Birkbeck College and is available on-line via the SEQNET facility of Daresbury Laboratory. It is expected that academic distribution will begin shortly and there are further plans for commercial distribution and continued support.
Recent developments in synthetic strategies with allylsilanes: from tetracoordinate to pentacoordinate allylsilanes
Authors: Sakurai Hideki
Published: November 2023

Allylsilanes are one of the most versatile reagents in organic synthesis and there are numerous examples of their applications. However, these reagents fall largely into the class of tetracoordinate allylsilanes. Currently, a new field of pentacoordinate allylsilanes is rapidly developing. Pentacoordinate allylsilicates react with aldehydes and ketones to give homoallyl alcohols with exceptionally high regio- and diastereoselectivity. The high reactivity of the allylsilicates is attributed to the significantly high Lewis acidity of the silicon centre to give hexacoordinate silicates (which allows for a six-membered cyclic transition state) as well as to the enhanced nucleophilicity of the -y-carbon of the allylsilicates arising from cr-1r conjugation. The stereochemical outcome of the reaction with pentacoordinate allylsilanes, which is completely different from that with tetracoordinate allylsilanes, should also find widespread use in organic synthesis. Reactions of pentacoordinate allylsilicates, which are remarkably different from those of the well established tetracoordinate allyltri methylsilanes, are described.
Alkoxy and acyloxy derivatives of silicon and tin and their uses as precursors for ceramics
Authors: Mehrotra Ram C
Published: November 2023

In view of the increasing importance of M―0―C derivatives, particularly the alkyl orthoesters, for glasses and ceramics, we present in this paper an account of the preparation of the title compounds, emphasizing the methods of synthesis discovered in the author’s laboratories. A brief account is also given of their physical properties and chemical reactions, and of their application potential, especially of bimetallic alkoxides of tin, as precursors for ceramics synthesized by the Sol-Gel process.
Organotin intermediates for organic synthesis
Authors: Neumann Wilhelm P
Published: November 2023

Progress in the generation and application of two important reactive organotin species for organic synthesis is reported. The first concerns the R Sn stannyl substituent and its use as a superior leaving group in electrophilic aromatic ipso-substitution, thus overriding the directing influences of other substituents; examples of its use are found in the acylation, formylation, sulphination, sulphonation and amidation of aromatics under mild conditions. The second deals with R Sn· radicals, especially new ways of generating these free from R SnH for the efficient free-radical synthesis of complicated target molecules. Two polymer-supported organotin hydrides based on a cross-linked polystyrene system in which the hydridostannyl group is separated from the aromatic ring by two CH units linkage, are also described.
New applications of metal hydrides in the synthesis of organosilanes and -germanes
Authors: Lukevics E , Gevorgyan V
Published: November 2023

New strategies for generating M―H (M=Si, Ge) bonds in high yields have been investigated. These are based on the reduction of M-X (X=Cl, Br, 0, N, C) bonds with Group 1-3 metal hydrides, the reactions being carried out in either one-phase or two-phase systems; the former involves the use of ethereal media in which the metal hydride is completely or partially soluble, while the latter involves the use of non-polar hydrocarbon solvents and appropriate phase-transfer catalysts or ultrasound irradiation. The M―C bond cleavage studies proved to be amenable only with heteroarylsilanes and -germanes. The influences of solvent, catalyst, type of reducing agent and the structure of the silane on the rate and selectivity of these reactions are discussed.
Silica induced cell damage and the protective effect of aluminium complexes
Authors: Kui Wang
Published: November 2023

Silicosis develops when the invading silica particles attack alveolar macrophagocytes, inducing cell damage. The lysosome membrane can be considered as the main target in the first stage of attack. Recently, Japanese and Russian scientists have postulated that the damage is mediated by free radicals which cause lipid peroxidation of the biomembranes and release of lysosomic enzymes. We have demonstrated that living cells respond to an exogenous substance as a multiple target system. Different target molecules are confined to different compartments. Owing to the compartmentalization of reactants, the reactions involved are localized and interrelated, leading to a sequence of events.
Determination of sub-ppm quantities of tin and distribution of tin in biological organisms
Authors: Chiba’’ Momoko , Shinohara Atsuko , Ujiie Chika
Published: November 2023

The determination of tin in biological materials was investigated by using a flameless atomic absorption spectrophotometer. A detection limit of 0.04 ng Sn could be achieved by ashing, reduction of coexisting Fe(III) to Fe(II), MIBK extraction, and AAS. When the organotin compound, tributyltin chloride, was administered to mice, large amounts of tin were found in the brains and only small amounts in the bones. On the other hand, when an identical dose of an inorganic compound such as stannous chloride was administered, large amounts were found in the bones and bone marrow cells and only small amounts in the brains.
Tin(IV) oxide-based materials. Surface chemistry, catalysis, and gas sensing
Authors: Harrison P G
Published: November 2023

Tin(IV) oxide and mixed Sn―M―O oxides have emerged as a very important class of materials with many areas of commercial application. This success has been founded not only upon empirically accrued information but also on fundamental chemical data. This article is intended to give an overview of the present state of the art in this area of tin chemistry from the chemical reactions which occur at the oxide-gas interface to the role of such materials in heterogeneous catalysis and in solid-state gassensing devices.
Theoretical models for ‘unusual’ coordination at silicon
Authors: Korkin Anatoli A
Published: November 2023

In the chemistry of silicon compounds, the labels ‘usual’ and ‘unusual’ that are used to describe the coordination of silicon are sometimes not explicit enough, and when we discuss the structures and properties of these compounds, we compare them, as a rule, with the carbon analogues. The threecoordinate doubly-bonded silicon molecules, for example, are considered ‘unusual’ because they are very reactive compared to ethenes. The violation of the octet rule and the formation of higher-than-four coordinate molecules are also ‘unusual’ in carbon chemistry, whereas it is well known that silicon forms many stable five- and six-coordinate compounds.
Studies on tris(phenyldimethylsilylmethyl)tin derivatives
Authors: Qinglan Xie , Jing Li , Zhiqiang Yang , Diankun, Zhang , Jitao Wang
Published: November 2023

With many drug molecules, the replacement of a carbon atom with a silicon atom is known to lead to a lowering of toxicity and a prolonged manifestation of the physiological effect. ‘Torque’, an acaricide developed by Shell in the 1970s, has the formula [(PhMe CCH)3Sn]2O. This acaricide has been derivatized to the (PhMe ECH)3SnX (X = Cl, ½O; E = C, Si) compounds, whose biological properties show that the silyl analogue of Torque was equally effective. By using [(PhMe SiCH)3Sn]2O (silyl-Torque) and (PhMe SiCH hSnCl as starting reagents, we have synthesized a series of tris(phenyldimethylsilylmethyl)aryloxy- and aklyloxyacetates [eqn (47.1)], arylcarboxylates [eqn (47.2)], and dithiophosphates [eqn (47.3)].
Cleavage of some βarylethyltriethylstannanes by aqueous methanolic perchloric acid
Authors: Attar-Bashi Moayad T
Published: November 2023

The acid catalysed exchange of hydrogen between the proton of trifluoroacetic acid and the methyl hydrogens of toluene and other methylarenes is a well documented reaction. In the acid cleavage studies of (Me SnC)Ar compounds, the trimethylstannylmethyl Me SnCH group behaves somewhat like the methyl group in that it releases Me Sn group with protic acids. For the reaction with benzyltrimethylstannane, the reaction is believed to be favoured by hyperconjugative stabilization of the Wheland intermediate and the delocalization of the positive charge onto the tin atom.
Reactions of sterically hindered organotin compounds
Authors: Brown Paul , Molloy, Kieran C , Mahon Mary F
Published: November 2023

Synthetic routes to sterically hindered organotins are discussed, with emphasis on some of the less expected products formed during reactions of molecules containing either the tristrimethylsilylmethyl or sterically substituted aryl ligands. The synthesis and structures of ring and cage compounds containing both O and S are presented, and the way such combinations can be used to tailor lattice structure are discussed.
The growth of the physical sciences
Authors: Laidler Keith J
Published: November 2023

There is a strong link between modern physical chemistry and the ancient science of mechanics. From the time of the ancient Greeks, who devoted much attention to mechanics, until the middle of the nineteenth century, progress in the physical sciences was to a large extent progress in the understanding of mechanical principles. The scope of mechanics is very wide. It deals with the motions of bodies ranging in size from massive stars to sub microscopic particles. It has application to the biological sciences and to engineering. It forms a basis for the kinetic theory of gases, for thermodynamics, and for molecular statistics. Even when quantum mechanics was introduced it by no means superseded classical mechanics, which still applies satisfactorily to all but sub microscopic particles.
Thermodynamics
Authors: Laidler Keith J
Published: November 2023

The word ‘thermo–dynamic’ was first used in 1849 in a paper presented by William Thomson (1824–1907) to the Royal Society of Edinburgh. Thomson was then a young professor of natural philosophy at the University of Glasgow, where he was to remain for over half a century. Later he was created Baron Kelvin of Largs, and although all his thermodynamic work was clone as Professor William Thomson it seems best to refer to him as Kelvin, if only to avoid confusion with various other Thomsons, Thomsens and Thompsons who worked in similar areas of research. When he wrote his 1849 paper Kelvin had been grappling for a few years with the ideas presented in a remarkable book which had been published in 1824 by Sadi Carnot, and with a paper by Chaperon that had appeared in 1834. Carnot’s book, which can be said to have inspired the whole subject of thermodynamics, was concerned with the performance of heat engines, and Kelvin was one of the first to appreciate its great importance. Carnot had based his treatment on the concept that heat is an ‘imponderable fluid’, but by 1849 Kelvin was just beginning to realize, mainly because of the work of James Prescott Joule, that heat is instead a form of energy. The idea was developing in Kelvin’s mind that in heat engines, such as the steam engines that were being used more and more, there is actually a conversion of heat into another form of energy, mechanical work. His word ‘thermo–dynamic’ was invented by him to refer to processes of this kind, and today we define thermodynamics as the science that deals with the interconversion of heat and work and all its applications.
Kinetic theory and statistical mechanics
Authors: Laidler Keith J
Published: November 2023

The kinetic theory of gases also played an important role in the development of physical chemistry. This theory, which evolved over a period of many decades, is concerned with understanding the behaviour of gases in terms of molecular motions. In its more advanced formulations the theory developed into statistical mechanics, which treats the properties of matter in a comprehensive way. Not match progress could be made with the kinetic theory of gases until the pressure–volume–temperature relationships had become established and until more was known about the nature of atoms. The gas laws were only properly understood by the middle of the nineteenth century, the final stumbling block being the problem of determining relative atomic masses. Kinetic theory and thermodynamics developed at the same time, through the efforts of many of the same investigators, and there was strong mutual support between the two subjects. Before the kinetic theory is discussed it will be useful to give brief accounts of the gas laws and of the development of ideas about the atomic nature of matter.
Chemical spectroscopy
Authors: Laidler Keith J
Published: November 2023

During the nineteenth century it became increasingly clear that spectroscopy has important chemical applications. Substances could often be identified by their spectra, and later in the century spectroscopy played an important role in the discovery of new elements. Spectra also provided valuable information about the nature of atoms and molecules, although sorting out the evidence was unexpectedly difficult–indeed impossible until the quantization of energy had been recognized. Some of the more important contributions to spectroscopy, especially in its chemical aspects, are listed in Table 6.1.
Electrochemistry
Authors: Laidler Keith J
Published: November 2023

Electrochemistry, concerned with the relationship between electricity and chemical properties, is a particularly important branch of physical chemistry, having a special significance for the rise of physical chemistry. The work in electrochemistry that was done in the 1880s by three men who were often known, sometimes derisively, as die loner–theIonists–played an especially important role in causing physical chemistry to become recognized as a separate and important branch of chemistry. The three men, van’t Hoff, Ostwald and Arrhenius, made important contributions also in other aspects of physical chemistry, particularly chemical kinetics, and were actively involved in the launching of the first journal devoted exclusively to physical chemistry, the Zeitschrifi fůr physikalische Chemie.The major achievements in electrochemistry are summarized in Table 7.1.The existence of what came to be called electricity was known to the ancient Greeks. Thales of Miletus (c.636–c.546 BC), statesman, mathematician, philosopher and engineer, made many important contributions to knowledge, and discovered that amber, when rubbed, acquires the property of attracting small pieces of pith or cork. Many centuries later William Gilbert (1540–1603) extended these observations, showing that other substances, such as glass and sulphur, show the same attracting properties when rubbed.
Chemical kinetics
Authors: Laidler Keith J
Published: November 2023

Today the study of the rates of chemical reactions, and of the factors on which they depend, is usually referred to as ‘ chemical kinetics’. The expression ‘ chemical dynamics’ is now applied to an important branch of chemical kinetics that is concerned with the details of the individual chemical events that occur during the course of a chemical reaction. There has been a change of meaning, since in the last century what we now call chemical kinetics was usually called chemical dynamics, which referred also to the study of matter at equilibrium. Ostwald, for example, in his 1904 Faraday Lecture, defined chemical dynamics as ‘ the theory of the progress of chemical reactions and the theory of chemical equilibrium’, and a similar definition was given by van’t Hoff in his Lectures 011 Theoretical and Physical Chemistry(1899–1900).Hardly any quantitative studies of the rates of chemical reactions were made until the latter part of the eighteenth century. In 1777 Karl Friedrich Wenzel (1740–1793), the Director of the foundries at Freiburg, described some measurements of the rates of solution of metals in acids but gave no details, merely saying that the rate increased with increasing concentration of acid. In 1818 the French chemist Louis Jacques The nard (1777–1857) described some studies of the rate of decomposition of hydrogen peroxide, a substance he had just discovered. The nard was a chemist of great distinction but like most other chemists of his time his main interest was in the isolation of new elements and compounds, and to him rate measurements were not of great interest or significance.
Introduction To Dilute Poly Atomic Gases
Authors: Mccourt Frederick R W , Beenakker Jan J M , Köhler Walter E , Kuščer Ivan
Published: November 2023

The present chapter discusses the ways in which gases of rotating molecules differ from monatomic gases and indicates the consequences that such differences have for the formulation of a valid kinetic theory of polyatomic gases and the description of nonequilibrium phenomena. The material presented here is intended to provide a general overview of the subject matter appearing in the following eight chapters, and is meant to place in perspective a number of developments that have taken place in the kinetic theory of dilute polyatomic gases.
Monolayer Physics
Authors: Bruch L W , Cole Milton W , Zaremba Eugene
Published: November 2023

‘In the structure of matter there can be no fundamental distinction between chemical and physical forces: it has been customary to call a force chemical, when it is more familiar to chemists, and to call the same force physical, when the physicist discovers an explanation of it.’ I. Langmuir, Phenomena, Atoms, and Molecules (Philosophical Library, NY, 1950) p.60 ‘ a (chemical] bond does not exist at all: it is a most convenient fiction... both to theoretical and experimental chemists.’ C. Coulson, quoted on p.261 of From Chemical Philosophy to Theoretical Chemistry, Mary Jo Nye (U. California, Berkeley, 1994)
General introduction
Authors: Jones John
Published: November 2023

The proteins are natural polymers which are assembled under nucleic acid control from a menu comprising nineteen L-a-amino acids of general structure 1 and the ‘imino’ acid L-proline (2): see Table 1.1. Amide or ‘peptide’ bonds link the building blocks, giving macromolecules (3) with ‘polypeptide’ backbones and pendant side-chains containing a variety of simple functionalities according to the amino acids selected.
α-Carboxy-protection
Authors: Jones John
Published: November 2023

With respect to acylation, the amino groups of amino acids and peptides are considerably more nucleophilic than their carboxy groups are. It follows that amino acids and peptides with unprotected carboxy groups can be used for peptide bond formation, if separately preactivated carboxy components are employed. Many reactions of this kind have been carried out successfully, but a policy of maximal protection is often adopted even when it is not strictly essential, because of solubility advantages, product isolation, and so forth.
A Utoca Tal Ysis In Well-Stirred Open Systems: The Isothermal Cstr
Authors: Gray Peter , Scott Stephen K
Published: November 2023

The sort of experiment which we have been considering so far involves the classic ‘closed vessel’. The term ‘closed’ is used here in its thermodynamic sense, i.e. there is no exchange of matter and, in particular, no inflow of fresh reactants, rather than implying that the vessel has a lid on it. Thus we may have been talking about a bulb of reacting gas closed by a tap or an ordinary beaker containing various solutions mixed together. Because such experiments are easiest to set up, most of the early work in oscillatory reaction kinetics was done in this way.
One-Dimensional Fourier Spectroscopy
Authors: Ernst Richard R , Bodenhausen Geoffrey , Wokaun Alexander
Published: November 2023

The advantages of Fourier spectroscopy over conventional slow-passage methods are well known. Although sensitivity was the primary objective for the introduction of Fourier techniques in 1965 (4.1,4.2), it is the versatility of time-domain experiments which explains the extraordinary development of modern NMR spectroscopy. On the one hand, Fourier spectroscopy allows the direct study of time-dependent phenomena such as relaxation and exchange processes. On the other hand, pulse experiments can easily be extended to incorporate polarization and coherence transfer. The separation of excitation and detection in distinct time intervals is of importance for many experiments and leads naturally to the segmentation of time in two-dimensional Fourier spectroscopy. In comparison with CW methods, Fourier spectroscopy has the additional advantage of circumventing lineshape distortions associated with fast sweeping and saturation.
The Collisionless Regime
Authors: Mccourt Frederick R W , Beenakker Jan J M , Kohler Walter E , Kuscer Ivan
Published: November 2023

As in Chapters 15 to 18, our attention will be focussed on phenomena related to molecular angular momentum. The behaviour of monatomic gases is well understood and has been described previously in several of the monographs mentioned in the introduction to Chapter 15. The presence of internal energy makes it necessary to take into account the accommodation of internal energy in collisions with the wall, but this introduces no essentially new phenomena in the kinetic theory. A different situation is encountered when molecular angular momentum is considered.
Shift Correlation Spectroscopy
Authors: Goldman Maurice
Published: November 2023

Shift correlation Spectroscopy is one of the most important methods of 2D NMR spectroscopy. Its purpose is to correlate the chemical shifts of spins between which there exists an indirect interaction, that is which belong to the same molecule and are not too far apart. It is usually referred to under the generic name of COSY (for Correlation SpectroscopY). As for J spectroscopy, it exists in two versions: homonuclear and heteronuclear. Although the excitation sequence is remarkably simple, especially in the homonuclear version, the theoretical calculations turn out to be among the most complex of all 2D methods, and they can be carried out only through the density matrix formalism.
Semiclassical Inversion Methods
Authors: Child M S
Published: November 2023

The semiclassical inversion of experimental data exploits the dependence of quantization conditions, expectation values, and various interference effects on phase integrals that contain explicit reference to the underlying potential energy function. Such phase integrals are amenable to an elegant Abelian transformation that allows one to extract the classical turning points at any chosen energy. Hence the resulting energy-dependent turning points may be used to define the required potential function.
Higher order cyanocuprates
Authors: Lipshutz Bruce H
Published: November 2023

Higher order (HO) cyanocuprates, stoichiometrically represented as ‘R2Cu(CN)Li2’, are distinctly different from the analogous lower order (LO) or Gilman cuprates R2CuLi by virtue of two distinguishing features: (1) they are believed to be copper(I) dianionic species, implying that three ligands are bound to a copper(I) centre; and (2) they contain a cyano group, which presumably imparts the required π-acidity to the lower order cyanocuprate RCu(CN)Li such that another equivalent of an organolithium can be accepted by the copper centre to afford [R2Cu(CN)2–2Li+]. Although there are reports on non-cyano-containing higher order cuprates, written according to the general formula ‘R3CuLi2’ relatively few synthetic uses of these have appeared to date. On the other hand, higher order cyanocuprates continue to evolve,1b, displaying unique properties including, as examples: (1) their ability to effect transmetallations with other organometallic species (see later); and (2) their ability to form kinetic reagents at low temperatures which lead via their oxidation to unsymmetrical biaryls with excellent selectivities.
Mechanistic studies of organocopper reactions
Authors: Smith R A J
Published: November 2023

Many different types of organocopper reagents have been used in organic synthetic procedures and the variety of reactions observed is also extensive. This synthetic efficiency has naturally promoted further extension and refinement and has also generated the inevitable questions regarding the mechanisms of these reactions. Mechanistic investigations in this area have therefore been undertaken for some considerable time and are aimed at rationalizing and directing further synthetic developments as well as increasing fundamental knowledge of a set of chemical reaction processes. It should be noted that the chemical behaviour of one type of organocopper reagent is sometimes very different from that of another reagent, and also organocopper reagents often react differently in different solvents. Hence, for practical application to a desired transformation it is often necessary to examine several types of organocopper reagents under different reaction conditions in order to attain the optimum reaction efficiency. The wide variation in the types of organocopper reagents and reaction conditions successfully used in synthesis creates many opportunities for mechanistic investigation. However, in many cases reaction parameters uncovered for one reaction-reagent combination may not be applicable to another, apparently related, system.
Maximum entropy, likelihood ranking and the phase problem in single crystal, powder diffraction and electron microscopy
Authors: Gilmore Christopher
Published: November 2023

Maximum entropy is a tool of Bayesian statistics, and thus is built around Bayes’ Theorem. In its simplest form, this theorem states that given two eventsE andF: where p( . ) denotes probability. The three components of this equation are termed the posterior, the prior and the likelihood respectively. In a Bayesian approach to statistics one first defines one's prior knowledge (How often do you start a scientific experiment with no prior knowledge i.e. a uniform prior?); likelihood is then used to consult the experimental data, and the two used to produce a posterior probability which reflects modifications to the prior which arise from the data.
Challenges in incommensurate and quasi-crystals
Authors: Paciorek W A
Published: November 2023

Quasi-periodic structure analysis is now a reasonably well established branch of crystallography. Indeed, quasi-crystallography can celebrate its 20th anniversary in 1992. Twenty years ago, during the 9th International Crystallography Conference in Kyoto, two contributions of prime importance were presented. In the first, P. M. de Wolff described the incommensurate phase of Na2CO3 using a higher dimensional space group. During the same session, A Janner presented the symmetry analysis of a vibrating crystal, using entirely the same formalism. This was the starting point for this new, rapidly developing field.
Salt-bridge interactions in the crystal structures of some biologically active alkaloid salts
Authors: Oleksyn B J , Kowalik J T , Serda P , Śliwiński J
Published: November 2023

From the moment when scientists became interested in the relationship between structure and activity of biologically important compounds, especially drugs, crystallographers have interpreted molecular shapes and dimensions from the viewpoint of the interactions between these molecules and their more or less known target systems in living organisms.
Disorder in the crystal structures of some ‘superflexible’ silahydrocarbons
Authors: Ovchinnikov Yu. E , Struchkov Yu. T
Published: November 2023

The subject of the present paper is the crystal structure and conformation of macrocyclic silahydrocarbons (MS) built of dicarbosilane units -C-SiR -Clinked by single, double or triple carbon-carbon bonds. The first representative of these MS, namely the 4-0 compound (Fig,1; the first digit is the number of Si atoms in the molecule, the second is the number in the series considered; the zero in this case indicates the structure solved by other authors), was structurally characterized in 1986 (Eliassen e,a. 1986), At the same time the crystal structure of another analogous macrocycle 6-1 with six silicon atoms was determined in our laboratory (Voronkov e.a. 1987).
Whither organic crystallography?
Authors: Jones D W
Published: November 2023

The careful measurement and reporting of crystal data -for example in the early volumes of Z.Krist -predates even the discovery of X-rays, let alone that of X-ray diffraction. Subsequently, crystallography has developed into a much broader discipline of structural science, based primarily on diffraction measurements but interacting significantly with other experimental techniques. If there is a crisis in organic crystallography, then it is arguable that this may have been with us for the last quarter of a century. During this time, the combination of automated data collection, direct structure-solving routines, and high-speed computing has progressively reduced the labour and difficulty of the structure elucidation of many “straightforward” crystals, such that many analyses, adequate for the purpose of structure confirmation, have been carried out by inexperienced or novice crystallographers.
Titanocene and zirconocene η-π complexes
Authors: Whitby Richard J
Published: November 2023

Titanium and zirconium are Group 4 transition metals. Both are compara tively cheap and non-toxic and as a result stoichiometric applications are practical. The +4 oxidation state is most common, with the +2 oxidation state being important in many reactions. Titanium also has an extensive chemistry in the +3 oxidation state. The high oxidation state makes the +4 complexes strong Lewis acids, a property which has been widely used in synthesis.
Classic matrix experiments
Authors: Dunkin Ian R
Published: November 2023

Anyone embarking on matrix-isolation studies will want to get on with their own ideas and experiments as soon as possible. There will be little incentive to spend time repeating the work of others. Nevertheless, it is valuable to gain confidence in new equipment or new techniques with some proven examples; so this chapter brings together a selection of matrix experiments from the literature, which can be carried out as tests or simply for fun. The author has carried out a good proportion of the experiments, but by no means all.
Introduction
Authors: Stone A J
Published: November 2023

The idea that matter is made up of atoms and molecules was known to the Greeks, though the evidence for it did not become persuasive until the eighteenth and nineteenth centuries, when the ideal gas laws, the kinetic theory of gases, Faraday’s laws of electrolysis, the stoichiometry of most chemical reactions, and a variety of other indications combined to decide the matter beyond doubt. In the twentieth century, further techniques such as X-ray diffraction and, more recently, high-resolution microscopy, have provided more evidence.
Molecules In Electrostatic Fields
Authors: Stone A J
Published: November 2023

Of the contributions to the interaction energy listed in Table 1.2, the electrostatic interaction is often the most important, as we shall see in later chapters. However all of the contributions to the interaction energy between molecules, except for the unimportant magnetic terms, derive ultimately from the Coulombic interactions between their particles. In order to develop the theory of all these effects, we need to be able to describe the way in which the charge is distributed in a molecule. For most purposes, this is done most simply and compactly by specifying its multipole moments, and while this description has its limitations it provides an essential part of the language that we use to discuss intermolecular forces.
Oxford and ‘big science’
Authors: Merricks Linda
Published: November 2023

Soddy spent almost the whole of the inter-war period at Oxford. He was appointed the Dr Lee’s Professor of Chemistry at Oxford in 1919, a post he held until he retired in 1936. With some reservations, in marked contrast to his years in Scotland, this could be described as a time of almost complete professional unhappiness. Just as his pre-First-World-War years were highly productive, during the inter-war period his scientific work was almost non-existent. However, it was a period in which political and economic work became more and more important to him. For these reasons the inter-war period may be conveniently, if rather artificially, divided into the more or less scientific and the more clearly political areas. Soddy himself would never have recognised this distinction—he always saw himself as a scientist whose science led him to a consideration of matters affecting the functioning of the wider society. However, for clarity, the areas of interest in his life during these decades will be considered in three chapters, the first looking at science, the second at his work on monetary theory in the 1920s and the third at his political involvement in the 1930s.
New Britain
Authors: Merricks Linda
Published: November 2023

To understand Soddy’s development during the next few years, we need to look at the New Britain Group, later known as the New Europe Group. This organization is now relatively unknown but, during the nineteen thirties, it gained a considerable following proposing reforms based on a tripartite programmer of cultural, economic and parliamentary changes which was developed through the period. The economic changes were closely based on Soddy’ s proposals and he was to become an influential member of the group. However, to understand the group during the thirties it is necessary to go back in time to the foundation of the group in inter-war London. This cultural world was characterized by numerous societies, clubs and associations, almost as many as there were individuals involved. Many of these groups had no formal membership, meeting place or publication, most of them were short-lived, while their agendas and programmers varied from merely eating and drinking to saving the whole world. Those who belonged to this world tended to associate with a range of organizations, passing from one to another according to what now look like whims, fancies and fashion. The favored description for these organizations was ‘ group ’ and this will be adopted as the most suitably loose designation. Most of them were geographically near each other, in London and generally near or in Bloomsbury. Even the original ‘Bloomsberries’, although by the late 1920s having their centers in Sussex and France, maintained close links with this area, and with the other, newer groups. The attraction of this part of London was due in part to historical accident—it had long been associated with an intellectual society, and this had led to or depended on the number of cafes, tearooms, restaurants and pubs where informal meetings and conversations could be held. The nearby houses were also still cheap and large enough to provide suitable premises for lecture rooms and offices.
The darkest days
Authors: Merricks Linda
Published: November 2023

The period of Soddy’s life from 1935 until after the Second World War was cryptically summed up in his obituary in The Times,‘Then after 1936, there was silence ... ‘ While not strictly accurate, this points to a problem in any attempt at a complete biography of Soddy. After 1936 he almost disappeared from the various areas so far discussed—science, monetary theories and New Britain—and, with some minor exceptions, the silence lasted until the late 1940s. Finally, there is almost no evidence for his activities during the whole of the Second World War. Unlike the other chapters of his life, the explanation for this is quite straightforward. The decade from 1935 was the worst of Soddy’s life. It was the period during which his professional life ended, his hopes for peace and prosperity were shattered and his worst fears about the implications of his atomic discoveries were realized. Perhaps worst of all, however, his personal happiness was destroyed when his wife, Winifred, died. She became ill in 1935 and then died on 17 August 1936. This marked the end of a remarkably contented twenty years of marriage. As his friend Sir John Russell wrote in 1956, ‘The death of his wife ... was a blow from which he never fully recovered’.