ANNUAL REPORTS ON NMR SPECTROSCOPY This Page Intentionally Left Blank ANNUAL REPORTS ON NMR SPECTROSCOPY Edited by G. A. WEBB Department of Chemistry, University of Surrey, Guildford, Surrey, England VOLUME 25 ACADEMIC PRESS Harcourt Brace J ovan0vich. Publishers London 0 San Diego 0 New York Boston 0 Sydney 0 Tokyo 0 Toronto ACADEMIC PRESS LIMITED 24-28 Oval Road, LONDON NWI 7DX US.Edition Published by ACADEMIC PRESS INC. San Diego, CA 92101 This book is printed on acid free paper Copyright 0 1993 ACADEMIC PRESS LIMITED All Rights Reserved No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical including photocopying, recording, or any information storage and retrieval system without permission in writing from the publisher A catalogue record for this book is available from the British Library ISBN 0-12-505325-8 ISSN 0066-4103 Phototypesetting by Alden Multimedia Ltd, Northampton Printed by HattnollsLimited, Bodmin, Cornwall List of Contributors L. Stefaniak, Institute of Organic Chemistry, Polish Academy of Sciences, Warsaw, Poland. G . A. Webb, Department of Chemistry, University of Surrey, Guildford, Surrey GU2 S X H , England. M. Witanowski, Institute of Organic Chemistry, Polish Academy of Sciences, Warsaw, Poland. Preface Annual Reports on NMR Spectroscopy contain several reports in earlier volumes on the very important topic of nitrogen NMR. The present volume consists of an update on these, the most recent of which appeared in Volume 18 published in 1986. The main aim of this account is to provide some coverage of the literature which has appeared since then. Once more I am very pleased to welcome Professors Stefaniak and Witanowski as my coauthors on this review. I would also like to take this opportunity to thank them most sincerely for their kind cooperation during the period of production of the present volume. University of Surrey Guildford, Surrey England G. A. WEBB February 1992 Contents List of Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . v Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi Nitrogen NMR Spectroscopy M . WITANOWSKI. L . STEFANIAK and G. A . WEBB 1. 2. 3. 4. 5. 6. 7. 8. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . Theory of nitrogen NMR parameters . . . . . . . . . . . . . . . Calibration techniques and sign conventions . . . . . . . . . . . . Experimental techniques . . . . . . . . . . . . . . . . . . . . . . General considerations of