This book explores chemical bonds, their intrinsic energies, and the corresponding dissociation energies which are relevant in reactivity problems. It offers the first book on conceptual quantum chemistry, a key area for understanding chemical principles and predicting chemical properties. It presents NBO mathematical algorithms embedded in a well-tested and widely used computer program (currently, NBO 5.9). While encouraging a "look under the hood" (Appendix A), this book mainly enables students to gain proficiency in using the NBO program to re-express complex wavefunctions in terms of intuitive chemical concepts and orbital imagery.
FRANK WEINHOLD, PhD, is Emeritus Professor of Physical and Theoretical Chemistry at the University of Wisconsin Madison. Professor Weinhold has served on the editorial advisory boards of the International Journal of Quantum Chemistry and Russian Journal of Physical Chemistry. He is the author of more than 170 technical publications and software packages, including the natural bond orbital program. CLARK R. LANDIS, PhD, is Professor of Inorganic Chemistry at the University of Wisconsin Madison. He has received teaching and lectureship awards for his contributions to chemical education. Dr. Landis's research focuses on catalysis in transition metal complexes.
Preface 1 Getting Started 1.1 Talking to your electronic structure system 1.2 Helpful tools 1.3 General $NBO keylist usage 1.4 Producing orbital imagery Problems and Exercises 2 Electrons in Atoms 2.1 Finding the electrons in atomic wavefunctions 2.2 Atomic orbitals and their graphical representation 2.3 Atomic electron configurations 2.4 How to find electronic orbitals and configurations in NBO output 2.5 Natural Atomic Orbitals and the Natural Minimal Basis Problems and Exercises 3 Atoms in Molecules 3.1 Atomic orbitals in molecules 3.2 Atomic configurations and atomic charges in molecules 3.3 Atoms in open-shell molecules Problems and Exercises 4 Hybrids and Bonds in Molecules 4.1 Bonds and lone pairs in molecules 4.2 Atomic hybrids and bonding geometry 4.3 Bond polarity, electronegativity, and Bent's rule 4.4 Electron-deficient 3-center bonds 4.5 Open-shell Lewis structures 4.6 Lewis-like structures in transition metal bonding Problems and Exercises 5 Resonance Delocalization Corrections 5.1 The Natural Lewis Structure perturbative model 5.2 2nd-order perturbative analysis of donor-acceptor interactions 5.3 $DEL energetic analysis 5.4 Delocalization tails of Natural Localized Molecular Orbitals 5.5 How to $CHOOSE alternative Lewis structures 5.6 Natural Resonance Theory Problems and Exercises 6 Steric and Electrostatic Effects 6.1 Nature and evaluation of steric interactions 6.2 Electrostatic and dipolar analysis Problems and Exercises 7 Nuclear and Electronic Spin Effects 7.1 NMR chemical shielding analysis 7.2 NMR J-coupling analysis 7.3 ESR spin-density distribution Problems and Exercises 8 Coordination and Hyperbonding 8.1 Lewis acid-base complexes 8.2 Transition metal coordinate bonding 8.3 Three-center, four-electron hyperbonding Problems and Exercises 9 Intermolecular Interactions 9.1 Hydrogen-bonded complexes 9.2 Other donor-acceptor complexes 9.3 Natural energy decomposition analysis Problems and Exercises 10 Transition State Species and Chemical Reactions 10.1 Ambivalent Lewis structures: the transition-state limit 10.2 Example: bimolecular formation of formaldehyde 10.3 Example: unimolecular isomerization of formaldehyde 10.4 Example: SN2 halide exchange reaction Problems and Exercises 11 Excited State Chemistry 11.1 Getting to the root of the problem 11.2 Illustrative applications to NO excitations 11.3 Finding common ground: state-to-state NBO transferability 11.4 NBO/NRT description of excited state structure and reactivity 11.5 Conical intersections and intersystem crossings Problems and Exercises Appendix A: What's Under the Hood? Appendix B: Orbital Graphics: The NBOView Orbital Plotter Appendix C: Digging at the Details Appendix D: What if Something Goes Wrong? Appendix E: Atomic Units and Conversion Factors