Lanthanide and Actinide Chemistry

SIMON COTTON, PHD, is a retired Honorary Senior Lecturer in Chemistry at the University of Birmingham, UK. He has decades of teaching and publishing experience in inorganic chemistry and related fields, and first worked with uranium and the lanthanides over fifty years ago; his ‘Soundbite Molecules’ column regularly appeared In the magazine Education in Chemistry for fifteen years, whilst he has written over 100 ‘Molecules of the Month’ at https://www.chm.bris.ac.uk/motm/motm.htm

About the Author xiii

Preface to the Second Edition xiv

Preface to the First Edition xv

About the Companion Website xvi

1 Introduction to the Lanthanides 1

1.1 Introduction 1

1.2 Characteristics of the Lanthanides 2

1.3 Occurrence and Abundance of the Lanthanides 2

1.4 Lanthanide Ores 3

1.5 Extracting and Separating the Lanthanides 5

1.5.1 Extraction 5

1.5.2 Separating the Lanthanides 5

1.6 The Position of the Lanthanides in the Periodic Table 8

1.7 The Lanthanide Contraction 8

1.8 Recycling Lanthanides 8

1.9 Isotopes 9

2 The Lanthanides – Principles and Energetics 13

2.1 Electron Configurations of the Lanthanides and f Orbitals 13

2.2 What Do f Orbitals Look Like? 14

2.3 How f Orbitals Affect Properties of the Lanthanides 15

2.4 The Lanthanide Contraction 16

2.5 Electron Configurations of the Lanthanide Elements and of Common Ions 16

2.6 Patterns in Ionization Energies 17

2.7 Atomic and Ionic Radii 18

2.8 Patterns in Hydration Energies (Enthalpies) for the Lanthanide Ions 19

2.9 Enthalpy Changes for the Formation of Simple Lanthanide Compounds 20

2.9.1 Stability of Tetrahalides 20

2.9.2 Stability of Dihalides 22

2.9.3 Stability of Aqua Ions 23

2.10 Patterns in Redox Potentials 24

3 The Lanthanide Elements and Simple Binary Compounds 28

3.1 Introduction 28

3.2 The Elements 28

3.2.1 Properties 28

3.2.2 Synthesis 29

3.2.3 Alloys and Uses of the Metals 30

3.3 Binary Compounds 30

3.3.1 Trihalides 30

3.3.2 Tetrahalides 32

3.3.3 Dihalides 32

3.3.4 Oxides 34

3.4 Borides 36

3.5 Carbides 36

3.6 Nitrides 37

3.7 Hydrides 37

3.8 Sulfides 37

4 Coordination Chemistry of the Lanthanides 40

4.1 Introduction 40

4.2 Stability of Complexes 40

4.3 Complexes 42

4.3.1 The Aqua Ions 42

4.3.2 Hydrated Salts 43

4.3.3 Other O-Donors 44

4.3.4 Complexes of β-Diketonates 46

4.3.5 Lewis Base Adducts of β-Diketonate Complexes 47

4.3.6 Nitrate and Carbonate Complexes 47

4.3.7 Crown Ether Complexes 48

4.3.8 Complexes of EDTA and Related Ligands 49

4.3.9 Complexes of N-Donors 50

4.3.10 Complexes of Porphyrins and Related Systems 51

4.3.11 Halide Complexes 52

4.3.12 Complexes of S-Donors 52

4.4 Alkoxides, Alkylamides, and Related Substances 53

4.4.1 Alkylamides 53

4.4.2 Alkoxides 54

4.4.3 Thiolates 56

4.4.4 Borohydrides 57

4.5 Coordination Numbers in Lanthanide Complexes 57

4.5.1 General Principles 57

4.5.2 Examples of the Coordination Numbers 58

4.5.3 The Lanthanide Contraction and Coordination Numbers 60

4.5.4 Formulae and Coordination Numbers 63

4.6 The Coordination Chemistry of the +2 and +4 States 63

4.6.1 The (+2) State 63

4.6.2 The (+4) State 66

4.7 Lanthanides in Living Systems 69

5 Electronic and Magnetic Properties of the Lanthanides 76

5.1 Magnetic and Spectroscopic Properties of the Ln3+ Ions 76

5.2 Magnetic Properties of the Ln3+ Ions 77

5.2.1 Adiabatic Demagnetization 79

5.2.2 Single Molecule Magnets (SMMs) and Single Ion Magnets (SIMs) 80

5.3 Energy-Level Diagrams for the Lanthanide Ions, and Their Electronic Spectra 84

5.3.1 Electronic Spectra 84

5.3.2 Hypersensitive Transitions 86

5.4 Luminescence Spectra 87

5.4.1 Quenching 92

5.4.2 Antenna Effects 92

5.4.3 Lanthanides in Upconversion 93

5.4.4 Applications of Luminescence to Sensory Probes 95

5.4.4.1 Terbium Luminescence to Detect Anthrax 97

5.4.4.2 Fingerprint Detection 97

5.4.5 Fluorescence and TV 98

5.4.6 Lighting Applications 99

5.4.7 Lasers 99

5.4.8 Euro Banknotes 100

5.5 NMR Applications 100

5.5.1 β-Diketonates as NMR Shift Reagents 100

5.5.2 Magnetic Resonance Imaging (MRI) 102

5.5.3 What Makes a Good MRI Agent? 102

5.5.4 Health Issues with MRI Agents 104

5.5.5 Texaphyrins 104

5.6 Electron Paramagnetic Resonance Spectroscopy 105

5.7 Lanthanides as Probes in Biological Systems 105

6 Organometallic Chemistry of the Lanthanides 110

6.1 Introduction 110

6.2 The +3 Oxidation State 110

6.2.1 Alkyls 111

6.2.2 Aryls 112

6.3 Cyclopentadienyls 113

6.3.1 Compounds of the Unsubstituted Cyclopentadienyl Ligand (C5H5 = Cp; C5Me5 =Cp∗) 113

6.3.2 Compounds [LnCp∗3] (Cp∗ = Pentamethylcyclopentadienyl) 116

6.3.3 Bis(cyclopentadienyl) Alkyls and Aryls LnCp2R 117

6.3.4 Bis(pentamethylcyclopentadienyl) Alkyls 118

6.3.5 Hydride Complexes 121

6.4 Cyclooctatetraene Dianion Complexes 121

6.5 The +2 State 122

6.5.1 Alkyls and Aryls 122

6.5.2 Cyclopentadienyls 123

6.5.3 Other Compounds 126

6.6 The +4 State 126

6.7 Metal–Arene Complexes 128

6.8 Carbonyls 129

6.9 Compounds with Lanthanide-Metal Bonds 129

7 The Misfits: Scandium, Yttrium, and Promethium 134

7.1 Introduction 134

7.2 Scandium 134

7.2.1 Binary Compounds of Scandium 135

7.3 Coordination Compounds of Scandium 136

7.3.1 The Aqua Ion and Hydrated Salts 136

7.3.2 Other Complexes 137

7.3.3 Alkoxides and Alkylamides 139

7.3.4 Patterns in Coordination Number 140

7.3.5 Scandium and Yttrium in the (+2) State 144

7.4 Organometallic Compounds of Scandium 145

7.5 Yttrium 148

7.6 Promethium 149

8 Introduction to the Actinides 154

8.1 Introduction and Occurrence of the Actinides 154

8.2 Synthesis 155

8.3 Extraction of Th, Pa, and U 157

8.3.1 Extraction of Thorium 157

8.3.2 Extraction of Protactinium 157

8.3.3 Extraction and Purification of Uranium 157

8.3.4 Uranium Extraction from Seawater 157

8.4 Uranium Isotope Separation 159

8.4.1 Gaseous Diffusion 159

8.4.2 Gas Centrifuge 160

8.4.3 Electromagnetic Separation 160

8.4.4 Laser Separation 160

8.5 Characteristics of the Actinides 160

8.6 Reduction Potentials of the Actinides 162

8.7 Relativistic Effects 163

9 Binary Compounds of the Actinides 165

9.1 Introduction 165

9.2 Halides 165

9.2.1 Syntheses of the Halides 167

9.2.2 Structure Types 168

9.3 Thorium Halides 170

9.4 Uranium Halides 170

9.4.1 Uranium(VI) Compounds 170

9.4.2 Uranium(V) Compounds 172

9.4.3 Uranium(IV) Compounds 172

9.4.4 Uranium(III) Compounds 173

9.4.5 Uranium Hexafluoride and Isotope Separation 173

9.5 Actinide Halides (Ac–Am) Excluding U and Th 175

9.5.1 Actinium 175

9.5.2 Protactinium 175

9.5.3 Neptunium 176

9.5.4 Plutonium 177

9.5.5 Americium 177

9.6 Halides of the Heavier Transactinides 178

9.6.1 Curium(III) Chloride 178

9.6.2 Californium(III) Chloride, Californium(III) Iodide, and Californium(II) Iodide 178

9.6.3 Einsteinium(II) Chloride 179

9.7 Oxides 179

9.7.1 Thorium Oxide 179

9.7.2 Uranium Oxides 180

9.7.3 Plutonium Oxides 180

9.8 Sulfides 180

9.9 Uranium Hydride UH3 181

9.10 Oxyhalides 181

10 Coordination Chemistry of the Actinides 184

10.1 Introduction 184

10.2 General Patterns in the Coordination Chemistry of the Actinides 185

10.3 Coordination Numbers in Actinide Complexes 185

10.4 Types of Complex Formed 187

10.5 Uranium and Thorium Chemistry 187

10.5.1 Uranyl Complexes 187

10.5.2 Coordination Numbers and Geometries in Uranyl Complexes 190

10.5.3 Some Other Complexes 192

10.5.4 Uranyl Nitrate and Its Complexes; Their Role in Processing Nuclear Waste 193

10.5.5 Nuclear Waste Processing 193

10.5.6 Uranium Oxo Complexes 194

10.5.7 Uranium Nitrido Complexes 195

10.5.8 Uranium(V) Complexes 196

10.5.9 Uranium(III) Complexes 197

10.5.10 Uranium(II) Complexes 198

10.6 Complexes of the Actinide(IV) Nitrates and Halides 199

10.6.1 Thorium Nitrate Complexes 199

10.6.2 Uranium(IV) Nitrate Complexes 200

10.6.3 Complexes of the Actinide(IV) Halides 200

10.7 Thiocyanates 202

10.8 Amides, Alkoxides, and Thiolates 203

10.8.1 Amide Chemistry 203

10.8.2 Alkoxides and Aryloxides 207

10.8.3 Borohydrides 209

10.8.4 Uranium Chelate Compounds 209

10.9 Chemistry of Actinium 210

10.10 Chemistry of Protactinium 211

10.11 Chemistry of Neptunium 212

10.11.1 Complexes of Neptunium 213

10.12 Chemistry of Plutonium 214

10.12.1 Aqueous Chemistry 214

10.12.2 Stability of the Oxidation States of Plutonium 215

10.12.3 Coordination Chemistry of Plutonium 216

10.12.4 Plutonium in the Environment 218

10.13 Chemistry of Americium and Subsequent Actinides 220

10.13.1 Potentials 220

10.14 Chemistry of the Later Actinides 222

11 Electronic and Magnetic Properties of the Actinides 228

11.1 Introduction 228

11.2 Absorption Spectra 229

11.2.1 Uranium (VI) – UO22+ – f0 229

11.2.2 Uranium(V) – f1 230

11.2.3 Uranium(IV) – f2 230

11.2.4 Spectra of the Later Actinides 233

11.3 Magnetic Properties 234

11.3.1 Uranium Single Molecule Magnets 236

12 Organometallic Chemistry of the Actinides 238

12.1 Introduction 238

12.2 Simple σ-Bonded Organometallics 238

12.3 Cyclopentadienyls 242

12.3.1 Oxidation State (VI) 242

12.3.2 Oxidation State (V) 242

12.3.3 Oxidation State (IV) 242

12.3.4 Oxidation State (III) 245

12.4 Compounds of the Pentamethylcyclopentadienyl Ligand (C5Me5 =Cp∗) 246

12.4.1 Oxidation State (IV) 246

12.4.2 Cationic Species and Catalysts 247

12.4.3 Hydrides 248

12.4.4 Oxidation State (III) 249

12.4.5 Oxidation State (II) 249

12.4.6 Some Recent Chemistry of Neptunium and Plutonium 251

12.5 Tris(pentamethylcyclopentadienyl) Systems 252

12.6 Other Metallacycles 252

12.7 Cyclooctatetraene Dianion Compounds 253

12.8 Arene Complexes 254

12.8.1 Simple Arene Derivatives 254

12.8.2 Arene-Supported Triazacyclononane Derivatives 254

12.9 Carbonyls 256

12.10 Compounds with Actinide-metal Bonds 257

13 Synthesis of the Transactinides and Their Chemistry 260

13.1 Introduction 260

13.2 Finding New Elements 261

13.3 Synthesis of the Transactinides 261

13.4 Naming the Transactinides 265

13.5 Predicting Electronic Arrangements 266

13.6 Identifying the Elements 266

13.7 Predicting Chemistry of the Transactinides 272

13.8 What Is Known about the Chemistry of the Transactinides 273

13.8.1 Element 104 273

13.8.2 Element 105 273

13.8.3 Element 106 274

13.8.4 Element 107 274

13.8.5 Element 108 274

13.8.6 Elements 112 and 114 276

13.9 And the Future? 276

References 278

Index 310