Molecular Magnetochemistry

Sergey G. Vulfson

Monsanto Corporation St. Louis, Missouri

Translated from the Russian by Rose P. Arshinova

Gordon and Breach Science Publishers Australia • Canada • China • France • Germany • India Japan • Luxembourg • Malaysia • The Netherlands Russia • Singapore • Switzerland CONTENTS

Preface xi

Illustration Acknowledgments xv

Introduction Magnetic Susceptibility as a Molecular Tensor Property 1

1 Determination of Average Magnetic Susceptibilities 15 1.1 Force Methods 15 1.1.1 The Gouy Method 15 1.1.2 The Quincke and Viscosimeter Methods 20 1.1.3 The Faraday Methods 23 1.2 Induction Methods 25 1.3 NMR Spectroscopy Methods 28 1.3.1 Methods of "Coaxial Ampoule" 29 1.3.2 Methods of "Fiat Ampoule" 38 1.4 Calibrating Standards 40 2 Methods of Determination of Anisotropie Magnetic Susceptibilities of Molecules 43 2.1 Methods Based on the Magnetooptical Phenomena 44 2.1.1 Zeeman Effect on Rotational Levels of Molecules 45 2.1.2 Magnetic Birefringence Effects in Transverse Magnetic Field 72 2.2 Nuclear Magnetic Resonance Spectroscopy 95 2.2.1 Nuclear Magnetic Resonance of Partial Oriented Molecules 95 2.2.2 Method of Pseudocontact (Dipole) Shifts 112 V1U Contents

2.3 Magnetochemistry of Single Crystals 119 2.4 On Correspondence of Results of Different Magnetic Methods 129

3 Relation Between Magnetic and Electric Properties of Molecules 149 3.1 Polarizability Tensor 149 3.1.1 General Presentation 149 3.1.2 Methods of Determining 151 3.1.3 Relation Between Optica] Polarizability and Magnetic Susceptibility 183 3.2 Dipole and Quadrupole Moments 193 3.2.1 The Buckingham Effect (Electric Field Gradient Birefringence) 200

4 Tensor Additivity of Molecular Electron Properties 225 4.1 Average Magnetic Susceptibilities 225 4.1.1 Pascal Systems 225 4.1.2 Diamagnetism of Ions 238 4.2 Additivity of Tensor Properties 246 4.2.1 Susceptibility and Polarizability 246 4.2.2 Determination of Susceptibility Anisotropies of Bonds from Spectral Data 283 4.3 "Atomic Dipoles" Method. Characteristic Properties of Tensor Additive Scheme of Quadrupole Moments 294

5 Magnetic Susceptibilities and Interatomic Interaction Effects 300 5.1 Magnetic Properties and Nature of Chemical Bond 300 5.2 Magnetic Susceptibility as Criterion of Aromaticity 305 5.3 Interactions in Paramagnetic Complexes 332 5.3.1 Mononuclear Metallocomplexes of 3D-Elements and Ligand Field Theory 332 5.3.2 Exchange Coupling in Molecules of Cluster Type 361 Contents ix

6 Determination of Three-Dimensional Structure of Molecules and Complexes 376 6.1 Application of the Cotton-Mouton Effect for Molecular Conformational Study 376 6.1.1 Conformations of Organic Molecules 377 6.1.2 Conformational Analysis of Organic Ions in Polar Media 381 6.1.3 Macromolecules, Bioparticles, and Liquid Crystals 384 6.2 Orientional Effects of Solvation 398 6.3 Paramagnetic Birefringence Effect and Three-Dimensional Structure of Lanthanide Complexes in Solutions 404

References 417

Subject Index 464