This book is intended as an easy to read supplement to the often brief descriptions of hydrogen bonding found in most undergraduate chemistry and molecular biology textbooks. It describes and discusses current ideas concerning hydrogen bonds ranging from the very strong to the very weak, with introductions to the experimental and theoretical methods involved.

This book deals with the phenomenological theory of first-order structural phase transitions, with a special emphasis on reconstructive transformations in which a group-subgroup relationship between the symmetries of the phases is absent. It starts with a unified presentation of the current approach to first-order phase transitions, using the more recent results of the Landau theory of phase transitions and of the theory of singularities. A general theory of reconstructive phase transitions is then formulated, in which the structures surrounding a transition are expressed in terms of density-waves, providing a natural definition of the transition order-parameters, and a description of the corresponding phase diagrams and relevant physical properties. The applicability of the theory is illustrated by a large number of concrete examples pertaining to the various classes of reconstructive transitions: allotropic transformations of the elements, displacive and order-disorder transformations in metals, alloys and related structures, crystal-quasicrystal transformations.

Technological and computational advances in the past decade have meant a vast increase in the study of crystalline matter in both organic, inorganic and organometallic molecules. These studies revealed information about the conformation of molecules and their coordination geometry as well as the role of intermolecular interactions in molecular packing especially in the presence of different intermolecular interactions in solids. This resulting knowledge plays a significant role in the design of improved medicinal, mechanical, and electronic properties of single and multi-component solids in their crystalline state. Understanding Intermolecular Interactions in the Solid State explores the different techniques used to investigate the interactions, including hydrogen and halogen bonds, lone pair-pi, and pi-pi interactions, and their role in crystal formation. From experimental to computational approaches, the book covers the latest techniques in crystallography, ranging from high pressure and in situ crystallization to crystal structure prediction and charge density analysis. Thus this book provides a strong introductory platform to those new to this field and an overview for those already working in the area. A useful resource for higher level undergraduates, postgraduates and researchers across crystal engineering, crystallography, physical chemistry, solid-state chemistry, supramolecular chemistry and materials science.

The last ten years have seen a revolution in our understanding of the mechanisms of biological crystal growth. While it had long been assumed that crystallisation would occur by the same classical mechanisms which form the basis for most descriptions of crystallisation processes, it is now becoming apparent that this is not the case. There are a number of key observations which have changed our view of crystallisation mechanisms. While it had long been assumed that crystalline biominerals typically form by ion-by-ion growth, it is now recognised that they often precipitate via amorphous precursor phases. This is well established for calcium carbonate and there is growing evidence that biogenic crystalline calcium phosphate phases may form via an analogous route. Recent re-examination of the structure of many calcium carbonate biominerals is also suggesting that "non-classical" crystallisation pathways, where crystals grow from the assembly of precursor particles, may also be widespread. Significantly, these mechanisms are not unique to the biological world. Possibly partly inspired by the identification of these biogenic mineralisation strategies, there is currently great interest from the general crystal growth community in these new and controversial ideas. A number of studies on crystal nucleation have recently re-examined classical nucleation theory, and the observation of pre-nucleation clusters is a recurrent theme of great interest. This controversial result apparently contradicts classical nucleation theory which leads the subject of crystal nucleation and growth via assembly to demand attention. The Scientific Committee warmly invites you to take part in this thought-provoking Discussion and looks forward to welcoming you to Leeds.

In recent years, there has been increasing activity in the research and design of optical systems based on liquid crystal (LC) science. Bringing together contributions from leading figures in industry and academia, Optical Applications of Liquid Crystals covers the range of existing applications as well as those in development. Unique in its thorough coverage of applications, not just the basic chemistry and physics of liquid crystals, the book begins with the existing applications of liquid crystals, from the ubiquitous LCD through to LC projectors and holography. The remaining chapters discuss more promising technologies in development, including photoaligning, photopatterning, and bistable twisted nematic LCs.

In the past decade, a number of orientational effects have been observed, produced by the passage of charged particles through crystals. These effects have a wide application in solid state physics, nuclear physics and the physics of hyperfine interactions. This book is not a survey but an introduction to this rapidly expanding branch of physics devoted to orientational effects and in particular to particle channelling in crystals. In it the authors discuss the interaction of charged particle beams with crystals and analyze the derivation of the fundamental equations describing this interaction. The channelling effect, the spatial redistribution of the particle flux and in the crystal lattice, and the problem of determining the position of an implanted atom in the lattice cell are also examined in detail. Student and postgraduate researchers as well as scientists and engineers working in experimental nuclear physics on the production of new materials and the physics of orientational effects, ion doping and solid state radiation physics may find this study useful.

The present volume continues the aim of Structure Reports to present critical accounts of all crystallographic structure determinations. Details of the arrange­ ment in the volumes, symbols used etc. are given in previous volumes (e. g. 41B or 42A, pages vi-viü). University of Guelph, G. FERGUSON Guelph, Ontario, Canada 1 May, 1993 STR UCTURE REPORTS for 1985 Volume52B Part2 STRUCTURE REPORTS for 1985 Valurne 52B (Part 2) ORGANIC SECTION General editor G. Ferguson Section editor G. Ferguson Published for the INTERNATIONAL UNION OF CRYSTALLOGRAPHY SPRINGER-SCIENCE+BUSINESS MEDIA, B. V. TABLE OF CONTENTS Introduction, VI Transition-metal Compounds (continued), 1103 Subject Index, 1902 Permuted Subject Index, 1993 Formula Index, 2053 Permuted Formula Index, 2078 Author Index, 2102 STRUCTURE REPORTS SECTIONID ORGANIC COMPOUNDS Edited by G. Ferguson with the assistance of C. H. Morgan D. F. Rendie S. J. Rettig S. N. Scrimgeour T. J. R. Weakley C. C. Wilson D. W. Young 2 ARRANGEMENT To find a particular organic or organometallic compound consult one of the indices (subject, permuted subject, formula or permuted formula) at the end of Part 2 of this volume. The general arrangement follows the classification used in the Cambridge Crystallographic Data Base and is: aliphatic or open chain compounds; open chains with N, S; benzene derivatives; c cyclic hydrocarbons; condensed ring systems; heterocyclic compounds; carbohydrates; amino acids; natural products; molecular complexes; organometallic compounds - B, Si, P, AJJ, Sb, groups lA, IIA, III, IV, VI; transition meta! complexes - . .