Coulson's. Valence. ROY McWEENY THIRD EDITION OXFORD UNIVERSITY PRESS

Transcription

1 Coulson's Valence ROY McWEENY THIRD EDITION OXFORD UNIVERSITY PRESS

2 Contents 1. THEORIES OFVALENCE Essentialsofany theory of valence Electronic character of valence Importance of the energy Energy diagrams Quantum chemistry WAVEFUNCTIONS: ATOMIC ORBITALS Wavefunctions The charge-cloud Interpretation of ^ The hydrogen atom ground State. Atomic units Atomic orbitals Electronic structureofatoms Approximate SCF orbitals. Screening constants WAVE-MECHANICAL PRINCIPLES The wave equation Stationary states Illustrative examples Some exactly solvable problems Need for an effective approximate method of solving the wave equation The Variation method Variation method for the ground State of the hydrogen atom The method of linear combinations Mutual repulsion of two energy curves: the non-crossing rule Morephysics QUALITATIVE MO THEORY: DIATOMIC MOLECULES Theories of electrons in molecules Molecular orbitals LCAO approximation The hydrogen molecule ion Hj The hydrogen molecule Homonuclear diatomic molecules Heteronuclear diatomic molecules Typesof molecular orbital

3 viii Contents 5. ELECTRON-PAIR WAVEFUNCTIONS 5.1. Two-electron wavefunctions 5.2. Some hydrogen molecule calculations 5.3. The valence bond (VB) method 5.4. Equivalence of MO and VB methods 5.5. The Coulson-Fischer wavefunction 5.6. Singlets and triplets: Pauli's exclusion principle 6. BONDING IN DIATOMIC MOLECULES 6.1. Some numerical calculations 6.2. Hybridization 6.3. Polar bonds 6.4. Electronegativity 6.5. Polar bonds: experimental implications 7. POLYATOMIC MOLECULES: STRUCTURE AND SHAPE 7.1. Localized bonds in polyatomic molecules: bond properties 7.2. Separability of localized bonds 7.3. Non-localized orbitals 7.4. The perfect-pairing approximation. Interaction between bonds 7.5. Inclusion of hybridization: H Principal types of s-p hybridization 7.7. Hybridization involving d Orbitals 7.8. Factors determining molecular shape 7.9. Valence rules Atomic radii, bond lengths, and bond energies 8. CARBON COMPOUNDS 8.1. Nature of the bonds in simple organic molecules 8.2. Heteroatoms, valence states, and molecular geometry 8.3. Conjugated and aromaticmolecules: benzene 8.4. Hückel theory: conjugated chains and rings 8.5. Alternant hydrocarbons. Charges and bond Orders 8.6. Alternant radicals and ions 8.7. Effects of heteroatoms and substituents 8.8. Improvements of the simple theory 8.9. Orbital energies and the total energy 9. TRANSITION-METAL COMPOUNDS 9.1. d-electrons in the transition elements 9.2. Crystal-field, or electrostatic, Splitting 9.3. A simple example: the Square planar complex 9.4. Other symmetries

4 Contents ix 9.5. The spectrochemical series Strong and weakfields: high-and low-spin complexes Ligand-field theory Relation with Pauling's octahedral hybrids Natureofthe7t-bonding Experimental evidence for electron delocalization i-Electron ligands Sandwich molecules. Ferrocene Simple semi-empirical theories CHEMICAL REACTIVITY Basis ofreactivity theories. Substitution reactions Isolated-molecule theory Localization theory Some applications to Substitution reactions Ring closing and opening. Woodward-Hoffmann rules Aromaticity. Evans-Dewar rules THE SOLID STATE The four main types of solid Energy band theory. Metals Brillouin zones Molecular crystals Covalent crystals Ionic crystals WEAK INTERACTIONS AND UNUSUAL BONDS Unusual types of bonding The hydrogen bond Bonds in electron-deficient molecules Phosphonitriles and related ring Systems Bonds in rare-gas Compounds Stereochemical and related interactions SELF-CONSISTENT FIELD THEORY The need for improved theories Ab initio SCF theory Semi-empirical SCF theory Tt-Electron calculations All-valence-electron calculations Comments on applications and future prospects 395

5 x Contents Appendix 1. Probabilities 398 Appendix 2. Angular momentum 403 Appendix 3. Group theory 409 References 417 Subject index 427 Units and periodic table 435