This book is about compounds such as the boron hydrides and associated metal hydrides and alkyls which acquired the label 'electron deficient' when they were thought to contain too few valence electrons to hold together. Though they are now recognized as containing the numbers of bonding electrons appropriate for their structures, the term 'electron deficient' is still commonly applied to many substances that contain too few valence electrons to provide a pair for every pair of atoms close enough to be regarded as covalently bonded. The study of such substances has contributed much to chemistry. Techniques for the vacuum manipulation of volatile substances were devised specifically for their study; developments in valence theory resulted from considerations of their bonding; and the reactivity of several (for example, diborane and complex metal hydrides, lithium and aluminium alkyls) has made them valuable reagents. The purpose of this book is to provide an introduction to the chemistry of these fascinating compounds. The experimental and spectroscopic methods by which they can be studied are outlined, the various types of structure they adopt are described and profusely illustrated, and the relative merits of extended valence bond and simple molecular orbital treatments of their bonding are discussed, with as liberal use of diagrams and as limited recourse to the Greek alphabet as possible. A recurring theme is the importance attached to considerations of molecular sym metry. Their reactions are treated in sufficient detail to show whether these reflect any deficiency of electrons.
The second edition of Organometallic Compounds (1960) was used not only by specialists but also as an undergraduate textbook. The third edition, recently published in two volumes, is about three times the length of the second and contains considerably more factual material than is appropriate for a student textbook. Therefore we believe that a shorter treatment would be welcome. In planning this book the authors have emphasized matters more of prin ciple than of detail, and have included in the first two chapters some general discussion of the properties and syntheses of organometallic compounds that is not to be found in the larger work. Some aspects of the organic chemistry of arsenic, and of silicon with particular reference to silicone polymers, are also included. Most university teachers of chemistry are becoming seriously concerned about the relentless increase in the amount and complexity of the material that is squeezed into undergraduate chemistry courses. With this in mind the authors have tried to cut detail to a minimum, but readers will find that the relative amount presented varies considerably between the various topics discussed. In general the treatment is more extensive than usual only if either or both of these conditions are met: (1), the subject has significant bearing on other major branches of chemistry including im portant industrial processes; (2), the topic is commonly misunderstood or found to be confusing.
to thank Messrs J. R. Sanders, W. E. Lindsell and M. G. Swanwick for helping to check the text and references and prepare indexes. Finally, I should like to thank my wife for the very considerable assis tance she has given me in the writing and production of this book. M. L. H. G. Contents Preface to the Third Edition, Volume Two Page v INTRODUCTION TO VOLUME TWO I Oassification I The IS-electron rule 2 (i) The basis of the I8-electron rule p. 4, (ii) Exceptions to the I8-electron rule p. 5 1. TWO-ELECTRON LIGANDS 7 A. Classification 7 B. The preparation of olefin-transition metal complexes 7 (a) Displacement of solvent ligands p. 9, (b) Preparations from metal carbonyls p. 9, (c) Less common preparative routes p. 11, Reductive olefination method p. 12 C. A molecular orbital description of the bonding in orga- metallic complexes 13 (a) General comments p. 13, (b) Symmetry considerations p. 13, (c) Energies of the molecular orbitals p. 14 D. A description of the bonding of 2-electron ligands to transition metals 14 E. General comments of 2-electron ligands 19 (a) Infrared studies p. 20, (b) Effect of olefin substituents p. 21, (c) The rotation of ethylene about the ligand-metal bond p. 22, (d) Chemical properties p. 23 F. Particular complexes of metals with 2-electron ligands 25 (a) Copper, silver and gold p. 25, Complexes with benzene p. 28, (b) Nickel, palladium and platinum p.
PREFACE. THE Author of this very practical treatise on Scotch Loch - Fishing desires clearly that it may be of use to all who had it. He does not pretend to have written anything new, but to have attempted to put what he has to say in as readable a form as possible. Everything in the way of the history and habits of fish has been studiously avoided, and technicalities have been used as sparingly as possible. The writing of this book has afforded him pleasure in his leisure moments, and that pleasure would be much increased if he knew that the perusal of it would create any bond of sympathy between himself and the angling community in general. This section is interleaved with blank shects for the readers notes. The Author need hardly say that any suggestions addressed to the case of the publishers, will meet with consideration in a future edition. We do not pretend to write or enlarge upon a new subject. Much has been said and written-and well said and written too on the art of fishing but loch-fishing has been rather looked upon as a second-rate performance, and to dispel this idea is one of the objects for which this present treatise has been written. Far be it from us to say anything against fishing, lawfully practised in any form but many pent up in our large towns will bear us out when me say that, on the whole, a days loch-fishing is the most convenient. One great matter is, that the loch-fisher is depend- ent on nothing but enough wind to curl the water, -and on a large loch it is very seldom that a dead calm prevails all day, -and can make his arrangements for a day, weeks beforehand whereas the stream- fisher is dependent for a good take on the state of the water and however pleasant and easy it may be for one living near the banks of a good trout stream or river, it is quite another matter to arrange for a days river-fishing, if one is looking forward to a holiday at a date some weeks ahead. Providence may favour the expectant angler with a good day, and the water in order but experience has taught most of us that the good days are in the minority, and that, as is the case with our rapid running streams, -such as many of our northern streams are, -the water is either too large or too small, unless, as previously remarked, you live near at hand, and can catch it at its best. A common belief in regard to loch-fishing is, that the tyro and the experienced angler have nearly the same chance in fishing, -the one from the stern and the other from the bow of the same boat. Of all the absurd beliefs as to loch-fishing, this is one of the most absurd. Try it. Give the tyro either end of the boat he likes give him a cast of ally flies he may fancy, or even a cast similar to those which a crack may be using and if he catches one for every three the other has, he may consider himself very lucky. Of course there are lochs where the fish are not abundant, and a beginner may come across as many as an older fisher but we speak of lochs where there are fish to be caught, and where each has a fair chance. Again, it is said that the boatman has as much to do with catching trout in a loch as the angler. Well, we dont deny that. In an untried loch it is necessary to have the guidance of a good boatman but the same argument holds good as to stream-fishing...
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