Table of Contents
Foreword vii
Preface ix
1 Symmetry elements and symmetry operations: molecular symmetry 1
1.1 Introduction 1
1.2 Molecular symmetry: in non-mathematical and geometrical sense 1
1.3 Symmetry operations and symmetry elements 2
1.4 Naming systems of notation for symmetry operations/elements 3
1.5 Proper axis of symmetry 4
1.6 Plane of symmetry 9
1.7 Center of symmetry/inversion center 15
1.8 Rotation-reflection axis or axis of improper rotations 17
1.9 Identity 26
Exercises 26
Multiple choice questions 26
Short answer type questions 27
Long answer type questions 27
2 Application of group theory to electronic spectroscopy 29
2.1 Introduction 29
2.2 Electronic spectroscopy 29
2.2.1 Electronic spectra of organic compounds 29
2.2.2 Allowed and forbidden transition: prediction through group theory 30
2.2.3 Vibronic coupling 33
2.2.4 Charge transfer spectra in simple and coordination compounds 45
2.2.5 Electronic spectra of transition metal complexes 49
2.2.5.1 Determination of Ttrms or term symbols 49
2.2.5.2 Assignment of term symbols of different atoms 51
2.2.5.3 Terms for atoms having more than one electron 52
2.2.6 Hund's Rules: determination of ground state terms for many electron atoms/ions 57
2.2.7 Hole formulation: term symbols for pn and p6-n and dn and d10-n configurations 60
2.2.8 Symmetry species of terms 60
2.2.9 Splitting of terms: step to arrive to Orgel diagrams 62
2.2.10 How to decide the ground state in group theoretical terms as Mulliken symbols in cubic field? 62
2.2.10.1 Tetrahedral complexes with d1 and d9 electronic configurations 65
2.2.10.2 Octahedral complexes with d4 and d6 electronic configurations 66
2.2.10.3 Octahedral complexes with d2, d8 and Td complexes with d2 electronic configurations 69
2.2.10.4 Octahedral complexes with d3, d7 and Td complexes with d2, d3, d7, d8 electronic configurations 73
2.2.10.5 Octahedral complexes with d5 electronic configuration 79
2.3 Effect of Jahn-Teller distortion on electronic spectra of complexes 80
2.4 Correlation diagram: ordering of energy states 90
2.5 Correlation diagram and Hole formalism 110
2.5.1 Uses of correlation diagrams 110
2.6 Tanabe-Sugano correlation diagram 111
2.7 Variation in Racah parameter B: nephelauxetic series 117
2.7.1 Evaluation of Dq, B' and β parameters 119
Exercises 139
Multiple choice questions/fill in the blanks 139
Short answer type questions 140
Long answer type questions 141
3 Molecular symmetry and group theory to vibrational spectroscopy 143
3.1 Introduction 143
3.2 Generation of reducible representation 149
3.3 Symmetry selection rules for IR and Raman spectroscopy: identification of IR and Raman active vibrations 202
3.4 Complementary nature of IR and Raman spectra 207
3.5 The mutual exclusion principle/rule 208
3.6 Polarization of Raman lines 210
3.7 Prediction of IR and Raman active modes in some molecules of different point Groups 211
3.8 Complications in IR and Raman spectra and difficulties in assignments 310
3.8.1 Overtones, combination band, hot bands and Fermi resonance 310
3.8.2 Overtones 311
3.8.3 Method for finding overtones for degenerate vibrational modes 312
3.8.4 Combination bands 319
3.8.5 Hot bands 323
3.8.6 Fermi resonance 323
3.9 Ascent-descent or group-subgroup in symmetry: interpretation of spectral data 325
3.10 IR and Raman spectra of linear molecules 331
3.10.1 Inspection method 333
3.10.2 Subgroup method 335
3.10.3 Integration method 346
3.11 Structural diagnosis: application of infrared and Raman spectra 349
3.11.1 Predicting /fitting structure/geometry of molecule 350
3.12 Prediction of coordination sites and linkage isomerism 355
3.13 Denticity assignment for anionic ligands 359
3.14 Geometrical isomers: distinction 366
3.15 Metal carbonyls: structural elucidation 368
Exercises 374
Multiple choice questions/fill in the blank 374
Short answer type questions 375
Long answer type questions 375
4 Chemical reactions: orbital symmetry rules 377
4.1 Introduction 377
4.2 Chemical reactions: symmetry rules 378
4.3 Inorganic/organic reactions: symmetry considerations 381
4.4 Nucleophilic displacement reactions 394
4.5 Berry's pseudorotation: orbital symmetry control 396
4.6 Correlation diagrams: prediction of orbital symmetry allowedness for Berry's pseudorotation 399
4.7 Stable shape of the molecules: symmetry rules 400
4.8 Symmetry controlled pericyclic reactions 403
4.9 Classes of pericyclic reactions 403
4.10 Interpretation of pericyclic reactions: different approaches 406
4.11 Woodward-Hoffmann approach 407
4.11.1 Symmetry allowed and symmetry forbidden reactions in pericyclic reactions 412
4.11.2 Conservation of orbital symmetry 412
4.11.3 Conrotatory and disrotatory ways of movement in pericyclic reaction 413
4.11.4 σ, π and ω orbitals and electrons 415
4.11.5 Components in pericyclic reactions 415
4.12 Mechanistic interpretation of some pericyclic reactions with symmetry property 416
4.13 Frontier molecular orbital approach: interpretation of pericyclic reactions 428
4.14 Woodward and Hoffmann's rules and FMO approach: electrocyclic reactions on the basis of components 433
Excercises 438
Multiple choice questions/fill in the blank 438
Short answer type questions 439
Long answer type questions 439
Appendix I 441
Appendix II 455
Appendix III 457
Bibliography 459
Index 461
