This book provides qualitative molecular orbital and valence-bond descriptions of the electronic structures for electron-rich molecules, with strong emphasis given to the valence-bond approach. Electron-rich molecules form an extremely large class of molecules, and the results of quantum mechanical studies from different laboratories indicate that qualitative valence-bond descriptions for many of these molecules are incomplete in so far as they usually omit "long-bond" Lewis structures from elementary descriptions of bonding. For example, the usual representation for the electronic structure of the ground-state for 03 involves resonance between the (+1 o and Until standard Lewis structures ~ ~ (-I . b:'" ~d· . . . . , recently, any contribution to resonance of the "long-bond" (or spin-paired o / ,. . has been largely ignored. diradica~ Lewis structure However, it :0 . 0. . e-. . . . . ______ " has now been calculated to be a very important structure. For the ground-states of numerous other systems, calculations also indicate that "long-bond" structures are more important than is usually supposed, and therefore they should frequently be included in qualitative valence-bond descriptions of electronic structure. The book describes how this may be done, and some of the resulting consequences for the interpretation of the electronic structure, bond properties and reactivities of various electron-rich molecules. When appropriate, molecular orbital and valence bond descriptions of bonding are compared, and relationships that exist between them are derived.
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ISBN-13
978-3-642-93216-8 (9783642932168)
DOI
10.1007/978-3-642-93216-8
Schweitzer Klassifikation
1 Atomic Orbitals, Electron Spin, Linear Combinations.- 2 Pauling "3-Electron Bonds", 4-Electron 3-Centre Bonding and the Need for an "Increased-Valence" Theory.- 3 Wave-Functions and Valence-Bond Structures for 1-Electron Electron Bonds, Electron-Pair Bonds, Pauling "3-Electron Bonds" and "No Bonds".- 4 Valence-Bond Structures for Some Diatomic Molecules.- 5 Pauling "3-Electron Bonds" and Hypoligated Transition Metal Complexes.- 6 Pauling "3-Electron Bonds", 5-Electron 3-Centre Bonding and Some Tetra-Atomic Radicals.- 7 Some Dimers of Triatomic Radicals with 17 and 19 Valence-Shell Electrons.- 8 Some Cu(II) Binuclear Transition-Metal Cluster Complexes.- 9 Excited States.- 10 Pauling "3-Electron Bonds" and "Increased-Valence" Theory for N2O4.- 11 Pauling "3-Electron Bonds" and "Increased-Valence" Structures.- 12 "Increased-Valence" Structures Constructed from Lewis Structures: Delocalization of Lone-Pair Electrons into Vacant Bonding Orbitals.- 13 "Increased-Valence" Structures for N-Centre Bonding Units.- 14 Delocalization of Lone-Pair Electrons into Anti-Bonding Orbitals: "Increased-Valence" Structures, Molecular Orbital Theory and Atomic Valencies.- 15 Slater Determinants and Wave-Functions for "Increased-Valence" Structures.- 16 Classical Valence Structures and Quinquevalent Nitrogen Atoms.- 17 Some Tetrahedral Molecules and d?-P? Bonding for Some Sulphur Compounds.- 18 Transition Metal Complexes With CO, N2, NO and O2 Ligands.- 19 Some Electron-Excess ?-Bonded Systems.- 20 Intermolecular Donor-Acceptor Complexes.- 21 Base-Displacement Reactions and Electron Conduction in Alkali Metals.- 22 Free-Radical and Spin-Paired Diradical Reactions.- 23 Some Comparisons of Types of Wave-Functions for 4-Electron3-Centre Bonding Units.- 24 A Note on Pauling "3-Electron Bonds" and Covalent-Ionic Resonance.- Appendix Atomic Orbital Overlap and Resonance between Standard and "Long-Bond" Lewis Structures.
