Spin-Crossover Materials

The phenomenon of spin-crossover has a large impact on the physical properties of a solid material, including its colour, magnetic moment, and electrical resistance. Some materials also show a structural phase change during the transition. Several practical applications of spin-crossover materials have been demonstrated including display and memory devices, electrical and electroluminescent devices, and MRI contrast agents. Switchable liquid crystals, nanoparticles, and thin films of spin-crossover materials have also been achieved.

Spin-Crossover Materials: Properties and Applications presents a comprehensivesurvey of recent developments in spin-crossover research, highlighting the multidisciplinary nature of this rapidly expanding field. Following an introductory chapter which describes the spin-crossover phenomenon and historical development of the field, the book goes on to cover a wide range of topics including

• Spin-crossover in mononuclear, polynuclear and polymeric complexes

• Structure: function relationships in molecular spin-crossover materials

• Charge-transfer-induced spin-transitions

• Reversible spin-pairing in crystalline organic radicals

• Spin-state switching in solution

• Spin-crossover compounds in multifunctional switchable materials and nanotechnology

• Physical and theoretical methods for studying spin-crossover materials

Spin-Crossover Materials: Properties and Applications is a valuable resource for academic researchers working in the field of spin-crossover materials and topics related to crystal engineering, solid state chemistry and physics, and molecular materials. Postgraduate students will also find this book useful as a comprehensive introduction to the field.

Auteur

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.

Contenu
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 B...