Chapter 1 Introduction to Inorganic Rings and Polymers
1.1 Classification ............................................. 1
1.2 Historical Background ...................................... 2
1.3 Industrial Applications .................................... 2
1.4 Scope and Limitations ...................................... 3
1.5 Organisation ............................................... 3
1.6 Nomenclature ............................................... 4
1.7 Bibliography ............................................... 4
References ...................................................... 5
Chapter 2 Synthetic Methods
2.1 Cyclocondensation Reactions ................................ 7
2.2 Reductive Coupling ........................................ 11
2.3 Dehydrocoupling ........................................... 13
2.4 Alkane Elimination Reactions .............................. 15
2.5 Cycloaddition Reactions ................................... 16
References ..................................................... 18
Chapter 3 Characterisation Methods
3.1 X-ray and Electron Diffraction ............................ 21
3.2 Chromatography ............................................ 23
3.3 Mass Spectrometry ......................................... 24
3.4 Nuclear Magnetic Resonance (NMR) Spectroscopy ............. 25
3.4.1 Introduction ....................................... 25
3.4.2 Applications ....................................... 27
3.4.3 Spin System Notation ............................... 30
3.5 Infrared and Raman Spectroscopy ........................... 31
3.6 Electron Paramagnetic Resonance (EPR) Spectroscopy ........ 33
3.7 UV-Visible Spectroscopy ................................... 36
References ..................................................... 37
Chapter 4 Electronic Structure and Bonding
4.1 Derealisation (Aromaticity) in Inorganic Rings ............ 39
4.1.1 Introduction ....................................... 39
4.1.2 π-Electron Derealisation ........................... 40
4.1.3 σ-Electron Derealisation ........................... 45
4.2 Frontier Orbital Considerations ........................... 45
4.2.1 Introduction ....................................... 45
4.2.2 π*-π* Interactions ................................. 46
4.2.3 Formation of Inorganic Ring Systems ................ 48
4.2.4 Reactivity of Inorganic Ring Systems ............... 50
References ..................................................... 50
Chapter 5 Paramagnetic Inorganic Rings
5.1 Neutral Radicals .......................................... 53
5.1.1 Homocyclic Systems ................................. 53
5.1.2 Heterocyclic Systems ............................... 54
5.2 Cation Radicals ........................................... 55
5.2.1 Homocyclic Systems ................................. 55
5.2.2 Heterocyclic Systems ............................... 56
5.3 Anion Radicals ............................................ 56
5.4 Biradicals ................................................ 58
5.4.1 Stable Biradicals .................................. 58
5.4.2 Biradicaloids ...................................... 59
5.4.3 Biradicals as Reaction Intermediates ............... 62
References ..................................................... 64
Chapter 6 Inorganic Macrocycles
6.1 Homocyclic Systems ........................................ 67
6.2 Heterocyclic Systems ...................................... 68
6.2.1 Saturated Rings .................................... 68
6.2.2 Unsaturated Rings .................................. 71
6.3 Host-Guest Chemistry ...................................... 74
6.4 Supramolecular Assemblies ................................. 77
References ..................................................... 80
Chapter 7 Ligand Chemistry
7.1 σ-Complexes ............................................... 82
7.1.1 Homocyclic Ligands ................................. 82
7.1.2 Heterocyclic Ligands ............................... 86
7.1.3 Macrocyclic Ligands ................................ 88
7.2 π-Complexes ............................................... 90
7.2.1 Homocyclic Systems ................................. 91
7.2.2 Heterocyclic Systems ............................... 93
References ..................................................... 94
Chapter 8 Synthesis and Characterisation of Inorganic
Polymers
8.1 Synthesis of Inorganic Polymers ........................... 98
8.1.1 Challenges ......................................... 98
8.1.2 Ring-opening Polymerisation (ROP) ................. 100
8.2 Characterisation of Inorganic Polymeric Materials ........ 102
8.2.1 Structural Characterisation ....................... 102
8.2.2 Molecular Weights and Molecular Weight
Distributions ..................................... 103
8.2.3 Thermal Transitions: Amorphous and Crystalline
Polymers .......................................... 104
8.2.4 Chain Conformations ............................... 107
8.2.5 Thermal Stability: Thermogravimetric Analysis ..... 107
References .................................................... 108
Chapter 9 Group 13: Rings and Polymers
9.1 Homoatomic Systems ....................................... 110
9.1.1 Neutral Rings ..................................... 110
9.1.2 Anionic Rings ..................................... 113
9.2 Boron-Nitrogen Rings ..................................... 116
9.2.1 Borazines ......................................... 116
9.2.2 Other Unsaturated Boron-Nitrogen Rings ............ 120
9.2.3 Saturated Boron-Nitrogen Rings (Cycloborazanes) ........ 124
9.2.4 Applications of Boron-Nitrogen Rings .............. 125
9.2.5 Boron-Nitrogen Polymers ........................... 126
9.3 Boron-Phosphorus Rings ................................... 128
9.3.1 Unsaturated Systems ............................... 128
9.3.2 Cyclic Biradicals ................................. 130
9.3.3 Saturated Systems ................................. 133
9.3.4 Boron-Phosphorus Chains and Polymers .............. 134
9.4 Aluminium-, Gallium- and Indium-Nitrogen Rings ........... 135
9.4.1 Unsaturated Systems ............................... 135
9.4.2 Saturated Systems ................................. 138
9.5 Aluminium-, Gallium- and Indium-Pnictogen Rings .......... 138
9.5.1 Unsaturated Systems ............................... 138
9.5.2 Saturated Systems ................................. 140
9.5.3 Single-source Precursors for III-V
Semiconductors .................................... 142
9.6 Boron-Chalcogen Rings .................................... 143
9.6.1 Boron-Oxygen Rings ................................ 143
9.6.2 Boron-Sulfur and -Selenium Rings .................. 144
9.7 Aluminium-, Gallium- and Indium-Oxygen Rings ............. 147
9.8 Aluminium-, Gallium- and Indium-Chalcogen Rings .......... 148
References .................................................... 150
Chapter 10 Group 14: Rings and Polymers
10.1 Homoatomic Rings and Polymers: Saturated Systems ......... 159
10.1.1 Cyclopolysilanes .................................. 159
10.1.2 Cyclopolygermanes, -stannanes and -plumbanes ...... 162
10.1.3 Cyclic Polyanions of Silicon, Germanium, Tin and
Lead .............................................. 165
10.1.4 Polymers with Backbones of Heavier Group 14
Elements .......................................... 167
10.2 Homoatomic Rings: Unsaturated Systems .................... 170
10.2.1 Three-membered Rings .............................. 170
10.2.2 Four-membered and Larger Rings .................... 174
10.3 Silicon- Germanium- and Tin-Nitrogen Rings ............... 179
10.3.1 Saturated Systems ................................. 179
10.3.2 Unsaturated Systems and Biradicals ................ 181
10.3.3 Silicon-Nitrogen Polymers: Ceramic Precursors ..... 184
10.4 Silicon-, Germanium- and Tin-Phosphorus Rings ............ 184
10.5 Silicon- Germanium- and Tin-Oxygen Rings ................. 187
10.6 Silicon-Oxygen Polymers: Polysiloxanes (Silicones) ....... 193
10.7 Silicon-, Germanium-, Tin- and Lead-Chalcogen Rings ...... 196
10.7.1 (R2ME)n (M=Si, Ge, Sn, Pb; E=S, Se, Те) and
Metal-rich Rings .................................. 196
10.7.2 Chalcogen-rich Rings .............................. 201
References .................................................... 202
Chapter 11 Group 15: Rings and Polymers
11.1 Nitrogen-rich Rings ...................................... 212
11.1.1 Nitrogen Homocycles: Energetic Materials .......... 212
11.1.2 Tetrazoles ........................................ 213
11.2 Cyclic Anions of Phosphorus, Arsenic, Antimony and
Bismuth .................................................. 213
11.3 Homoatomic Rings and Polymers ............................ 217
11.3.1 Cyclophosphines ................................... 217
11.3.2 Cycloarsines, -stibines and -bismuthines .......... 226
11.3.3 Ladder Polymers (RE)n (E = As, Sb) ................ 230
11.4 Phosphorus-Nitrogen Rings and Polymers ................... 231
11.4.1 Cyclophosphazanes ................................. 231
11.4.2 Cyclophosphazenes ................................. 236
11.4.3 Polyphosphazenes .................................. 245
11.5 Arsenic-, Antimony-and Bismuth-Nitrogen Rings ............ 250
11.5.1 Cyclopnictazanes .................................. 250
11.5.2 Cycloarsazenes .................................... 252
11.6 Pnictogen-Oxygen Rings ................................... 252
11.6.1 Phosphorus-Oxygen Rings ........................... 252
11.6.2 Arsenic-, Antimony- and Bismuth-Oxygen Rings ...... 254
11.7 Pnictogen-Chalcogen Rings ................................ 255
11.7.1 Binary Phosphorus-Sulfur and -Selenium Rings ...... 255
11.7.2 Organophosphorus-Sulfur Rings ..................... 256
11.7.3 Organophosphorus-Selenium Rings ................... 258
11.7.4 Organophosphorus-Tellurium Rings .................. 259
11.7.5 Arsenic-, Antimony-and Bismuth-Chalcogen Rings .... 260
References .................................................... 264
Chapter 12 Group 16: Rings and Polymers
12.1 Neutral Sulfur, Selenium and Tellurium Rings ............. 276
12.1.1 Homoatomic Rings .................................. 276
12.1.2 Heteroatomic Rings ................................ 279
12.1.3 Ring Transformations .............................. 280
12.2 Oxidised Chalcogen Homocycles ............................ 282
12.2.1 With Exocyclic Oxygen Substituents ................ 282
12.2.2 With Exocyclic Halogen Substituents ............... 282
12.3 Cationic Chalcogen Rings ................................. 284
12.3.1 Homocyclic Sulfur and Selenium Cations ............ 285
12.3.2 Homocyclic Tellurium Cations ...................... 290
12.3.3 Heteroatomic Chalcogen Cations .................... 293
12.3.1 12.4 Anionic Chalcogen Rings and Chains ........... 294
12.4.1 Catena-Sulfm Anions ............................... 294
12.4.2 Catena- and Spirocyclic Selenium Anions ........... 296
12.4.3 Homoatomic Tellurium Anions ....................... 297
12.4.4 Heteroatomic Selenium-Tellurium Anions ............ 299
12.5 Polymeric Sulfur, Selenium and Tellurium ................. 300
12.6 Sulfur-Nitrogen Heterocycles ............................. 301
12.6.1 Saturated Sulfur-Nitrogen Rings: Cyclic Sulfur
Imides ............................................ 301
12.6.2 Unsaturated Sulfur-Nitrogen Rings ................. 304
12.7 Sulfur-Nitrogen Chains and Polymers ...................... 309
12.7.1 Poly(Sulfur Nitride) .............................. 309
12.7.2 Sulfur-Nitrogen Chains ............................ 311
12.7.3 Sulfanuric Polymers ............................... 311
12.8 Selenium-and Tellurium-Nitrogen Rings .................... 312
12.8.1 Cyclic Selenium and Tellurium Imides .............. 312
12.8.2 Unsaturated Systems ............................... 314
12.9 Sulfur-, Selenium- and Tellurium-Oxygen Rings and
Polymers ................................................. 317
References ............................................... 319
Subject Index ................................................. 328
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