Title Details

Malcolm Halcrow, Professor of Inorganic Chemistry, University of Leeds, UK
Professor Halcrow's independent research has spanned different areas of synthetic inorganic chemistry, but with particular interests in switchable metal complexes, supramolecular chemistry and crystal engineering. The synthesis and structural chemistry of spin-crossover materials has been his most active research area in the past ten years; since his first paper in the field in 2001, Professor Halcrow has published 34 papers directly related to spin-crossover, including three journal reviews which are widely cited in the spin-crossover literature.

List of Contributors xv

Preface xvii

1 The Development of Spin-Crossover Research 1
Keith S. Murray

1.1 Introduction 1

1.2 Discrete Clusters of SCO Compounds 4

1.3 1D Chains of FeII SCO Materials 22

1.4 1D Chains of FeIII SCO Materials 28

1.5 2D Sheets of FeII SCO Materials 29

1.6 3D Porous SCO Materials 30

1.7 Some Recent Developments in Mononuclear SCO FeII, FeIII and CoII Compounds 33

1.8 Multifunctional/Hybrid SCO Materials 37

1.9 Developments in Instrumental Methods in Spin-Crossover Measurements 40

1.10 Applications of Molecular Spin-Crossover Compounds 41

1.11 Summary 42

2 Novel Mononuclear Spin-Crossover Complexes 55
Birgit Weber

2.1 Introduction and General Considerations 55

2.2 Novel Coordination Numbers (CN), Coordination Geometries and Metal Centres 57

2.3 Iron Complexes with Novel Ligand Donor Atoms and New Ligand Systems 65

2.4 Other Examples 70

2.5 Conclusion and Outlook 72

3 Spin-Crossover in Discrete Polynuclear Complexes 77
Juan Olguin and Sally Brooker

3.1 Introduction 77

3.2 Dinuclear Iron(II) Complexes 79

3.3 Higher Nuclearity Iron(II) Compounds 98

3.4 Iron(III) 104

3.5 Cobalt(II) 109

3.6 Dinuclear Chromium(II) Complex 111

3.7 Concluding Remarks 112

4 Polymeric Spin-Crossover Materials 121
M. Carmen Munoz and Jose Antonio Real

4.1 Introduction 121

4.2 One-Dimensional SCO-CPs 121

4.3 Two-d = Dimensional SCO-CPs 128

4.4 Three-Dimensional SCO-CPs 133

4.5 Conclusion 138

5 Structure:Function Relationships in Molecular Spin-Crossover Materials 147
Malcolm A. Halcrow

5.1 Introduction 147

5.2 Molecular Shape 150

5.3 Crystal Packing 155

5.4 Cooperativity Mediated by Disorder 158

5.5 Compounds Showing Wide Thermal Hysteresis 158

5.6 Other Noteworthy Compounds 162

5.7 Conclusions 164

6 Charge Transfer-Induced Spin-Transitions in Cyanometallate Materials 171
Kim R. Dunbar, Catalina Achim and Michael Shatruk

6.1 Introduction 171

6.2 Characterization of CTIST Compounds 173

6.3 CTIST in Coordination Polymers 174

6.4 CTIST in Nanoscale Materials 189

6.5 CTIST in Polynuclear Transition Metal Complexes 195

6.6 Summary and Outlook 198

7 Valence Tautomeric Transitions in Cobalt-dioxolene Complexes 203
Colette Boskovic

7.1 Introduction 203

7.2 Induction of Valence Tautomeric Transitions 205

7.3 Other Factors that Contribute to the Valence Tautomeric Transition 210

7.4 Polynuclear Valence Tautomeric Complexes 214

7.5 Bifunctional Valence Tautomeric Complexes 218

7.6 Concluding Remarks 220

8 Reversible Spin Pairing in Crystalline Organic Radicals 225
Jeremy M. Rawson and John J. Hayward

8.1 Introduction 225

8.2 Radical Pairs: Solution and Gas Phase Studies 226

8.3 Dimerisation in the Solid State 229

8.4 Summary and Future Perspectives 234

9 Breathing Crystals from Copper Nitroxyl Complexes 239
Victor Ovcharenko and Elena Bagryanskaya

9.1 Introduction 239

9.2 Structural and Magnetic Anomalies 241

9.3 Relationship Between the Chemical Step and the Physical Property 245

9.4 Relationship Between the Thermally Induced Reorientation of Aromatic Solvate Molecules and the Character of the Magnetic Anomaly 251

9.5 EPR Study of Breathing Crystals 255

9.6 Classification of Spin-Transitions in Breathing Crystals and Correlations with Magnetic Susceptibility 261

9.7 The Detailed Magnetic Structure of Breathing Crystals 266

9.8 EPR-detected LIESST on Breathing Crystals 272

9.9 Conclusion 275

10 Spin-State Switching in Solution 281
Matthew P. Shores, Christina M. Klug and Stephanie R. Fiedler

10.1 Introduction and Scope 281

10.2 Spin-Crossover: Solid State Versus Solution 282

10.3 Practical Considerations 283

10.4 Spin-Crossover in Solution 285

10.5 Ligation Changes Driving Spin-State Switching in Solution 288

10.6 Second Coordination Sphere Triggers for Spin-State Switching 291

10.7 Challenges and Opportunities 294

10.8 Conclusions/Outlook 295

11 Multifunctional Materials Combining Spin-Crossover with Conductivity and Magnetic Ordering 303
Osamu Sato, Zhao-Yang Li, Zi-Shuo Yao, Soonchul Kang and Shinji Kanegawa

11.1 Introduction 303

11.2 Spin-Crossover and Conductivity: Spin-Crossover Conductors 303

11.3 Spin-Crossover and Magnetic Interaction: Spin-Crossover Magnets 308

12 Amphiphilic and Liquid Crystalline Spin-Crossover Complexes 321
Shinya Hayami

12.1 Introduction 321

12.2 Unique Magnetic Properties of SCO Cobalt(II) Compounds with Long Alkyl Chains 322

12.3 Liquid Crystalline SCO Compounds 325

12.4 Langmuir–Blodgett Films and Amphiphilic SCO Compounds 331

12.5 Conclusion and Outlook 339

13 Luminescent Spin-Crossover Materials 347
Helena J. Shepherd, Carlos M. Quintero, G´abor Molnar, Lionel Salmon and Azzedine Bousseksou

13.1 General Introduction 347

13.2 Introduction to Luminescent Materials and Luminescence Energy Transfer 348

13.3 Electronic Transitions and Optical Properties of Spin-Crossover Complexes 358

13.4 Materials with Combined Spin-Crossover and Luminescent Functionalities 361

13.5 Concluding Remarks 371

14 Nanoparticles, Thin Films and Surface Patterns from Spin-Crossover Materials and Electrical Spin State Control 375
Paulo Nuno Martinho, Cyril Rajnak and Mario Ruben

14.1 Introduction 375

14.2 Nanoparticles and Nanocrystals 376

14.3 Thin Films 387

14.4 Surface Patterns 393

14.5 Electrical Spin State Control 396

14.6 Conclusion 399

15 Ultrafast Studies of the Light-Induced Spin Change in Fe(II)-Polypyridine Complexes 405
Majed Chergui

15.1 Introduction 405

15.2 Properties of Fe(II) Complexes 406

15.3 From the Singlet to the Quintet State 408

15.4 Ultrafast X-Ray Studies 415

15.5 Summary and Outlook 417

16 Real-Time Observation of Spin-Transitions by Optical Microscopy 425
Francois Varret, Ahmed Slimani, Damien Garrot, Yann Garcia and Anil D. Naik

16.1 Introduction 425

16.2 Experimental Aspects 426

16.3 Selected Investigations 429

16.4 Conclusions and Prospects 439

17 Theoretical Prediction of Spin-Crossover at the Molecular Level 443
Robert J. Deeth, Christopher M. Handley and Benjamin J. Houghton

17.1 Introduction 443

17.2 Beginnings: Valence Bond and Ligand Field Theories 443

17.3 Quantum Chemistry 446

17.4 Empirical Methods 449

17.5 Conclusions 452

18 Theoretical Descriptions of Spin-Transitions in Bulk Lattices 455
Cristian, Enachescu, Masamichi Nishino and Seiji Miyashita

18.1 Introduction 455

18.2 Elastic Interaction Models for Spin-Crossover Systems 457

18.3 Mechano-Elastic Model 463

18.4 Conclusions 471

19 Optimizing the Stability of Trapped Metastable Spin States 475
Jean-Francois Letard, Guillaume Chastanet, Philippe Guionneau and Cedric Desplanches

19.1 Introduction 475

19.2 Light-Induced Excited Spin-State Trapping (LIESST) Effect 476

19.3 The T(LIESST) Approach: The Case of Mononuclear Compounds 479

19.4 The T(LIESST) Approach: An Extension to Polynuclear Iron(II) Complexes 487

19.5 Simulation and Extrapolation of a T(LIESST) Experiment 495

19.6 Conclusions 500

20 Piezo- and Photo-Crystallography Applied to Spin-Crossover Materials 507
Philippe Guionneau and Eric Collet

20.1 Introduction 507

20.2 Spin-Crossover and Piezo-Crystallography 507

20.3 Crystallography of Photoexcited SCO Materials 512

21 Spin-Transitions in Metal Oxides 527
Jean-Pascal RUEFF

21.1 Introduction 527

21.2 RIXS: A Probe of the 3d Electronic Properties 530

21.3 Experimental Results 533

21.4 Conclusions and Perspectives 538

References 540

Index