Contents -- Abbreviations -- 1 QUANTUM CHEMICAL FRAMEWORK -- 1.1 Quantum Chemical Techniques -- 1.1.1 Basis Sets -- 1.1.2 Electron Correlation -- 1.1.3 Geometries -- 1.2 Definition of a Hydrogen Bond -- 1.2.1 Geometry -- 1.2.2 Energetics -- 1.2.3 Electronic Redistributions -- 1.2.4 Spectroscopic Observations -- 1.3 Quantum Chemical Characterization of Hydrogen Bonds -- 1.3.1 H-bond Geometries -- 1.3.2 Thermodynamic Quantities -- 1.3.3 Electronic Redistributions -- 1.3.4 Spectroscopic Observations -- 1.4 A Simple Example -- 1.5 Sources of Error -- 1.6 Basis Set Superposition -- 1.6.1 Secondary Superposition -- 1.6.2 Important Properties of Superposition Error -- 1.6.3 Historical Perspective -- 1.7 Energy Decomposition -- 1.7.1 Kitaura-Morokuma Scheme -- 1.7.2 Alternate Schemes -- 1.7.3 Perturbation Schemes -- 2 GEOMETRIES AND ENERGETICS -- 2.1 XH···ZH[sub(3)] -- 2.1.1 BSSE -- 2.1.2 Substituent Effects -- 2.2 XH···YH[sub(2)] -- 2.2.1 Comparative Aspects -- 2.2.2 Angular Features -- 2.2.3 Alternate Complexes and Geometries -- 2.2.4 Energy Components -- 2.3 HYH···ZH[sub(3)] -- 2.3.1 Substituents -- 2.4 XH···XH -- 2.5 HYH···YH[sub(2)] -- 2.5.1 Binding Energy of Water Dimer -- 2.5.2 Complexes Containing H[sub(2)]S -- 2.5.3 Substituent Effects -- 2.6 (ZH[sub(3)])[sub(2)] -- 2.7 Carbonyl Group -- 2.7.1 Substituent Effects -- 2.8 Carboxylic Acid -- 2.8.1 Carboxylic Acid Dimers -- 2.9 Nitrile -- 2.10 Imine -- 2.11 Amide -- 2.11.1 Interaction with Carboxylic Acid and Ester -- 2.12 Nucleic Acid Base Pairs -- 2.13 H-Bonds versus D-Bonds -- 2.13.1 Water Molecules -- 2.14 Summary -- 3 VIBRATIONAL SPECTRA -- 3.1 Method of Calculation -- 3.2 Accuracy Considerations -- 3.3 (HX)[sub(2)] -- 3.4 H[sub(3)]Z···HX -- 3.4.1 Analysis of Intensities -- 3.4.2 Anharmonicity -- 3.4.3 Other Properties -- 3.4.4 Relationship between H-Bond Strength and Spectra.

3.5 H[sub(2)]Y···HX -- 3.5.1 Alkyl Substituents -- 3.5.2 Other Properties -- 3.6 H[sub(2)]Y···HYH -- 3.6.1 Polarizability -- 3.6.2 Comparison between (H[sub(2)]O)[sub(2)] and (H[sub(2)]S)[sub(2)] -- 3.6.3 Effects of Electron Correlation and Matrices -- 3.6.4 Substituent Effects -- 3.6.5 NMR spectra -- 3.7 Expected Accuracies -- 3.7.1 HF Dimer -- 3.7.2 Water Dimer -- 3.8 HYH···NH[sub(3)] -- 3.9 (NH[Sub(3)])[sub(2)] -- 3.10 Carbonyl Oxygen -- 3.10.1 Relationship between ΔE and Δv -- 3.10.2 Formaldehyde + Water -- 3.10.3 Formaldehyde + HX -- 3.11 Imine -- 3.12 Nitrile -- 3.12.1 Correlation and Anharmonicity -- 3.12.2 HCN as Proton Donor -- 3.12.3 HCN Dimer -- 3.13 Amide -- 3.14 Summary -- 4 EXTENDED REGIONS OF POTENTIAL ENERGY SURFACE -- 4.1 Ammonia Dimer -- 4.2 H[sub(2)]O···HX -- 4.3 (HX)[sub(2)] -- 4.3.1 Anisotropies of Energy Components -- 4.3.2 Interconversion Pathways -- 4.3.3 HCl Dimer -- 4.4 Water Dimer -- 4.4.1 Characterization of Possible Minima and Stationary Points -- 4.4.2 Components of the Interaction Energy -- 4.5 Carbonyl Group -- 4.6 Amines -- 4.7 Summary -- 5 COOPERATIVE PHENOMENA -- 5.1 HCN Chains -- 5.1.1 Geometries -- 5.1.2 Energetics -- 5.1.3 Dipole Moments -- 5.1.4 Vibrational Spectra -- 5.1.5 Quadrupole Coupling Constants -- 5.1.6 Cyclic Chains -- 5.2 HCCH Aggregates -- 5.2.1 Trimers -- 5.2.2 Tetramers and Pentramers -- 5.3 Hydrogen Halides -- 5.3.1 Open versus Cyclic Trimers -- 5.3.2 Three-Body Interaction Energies -- 5.3.3 Larger Oligomers -- 5.4 Water -- 5.4.1 Extended Open Chains -- 5.4.2 Branching Clusters -- 5.4.3 Cyclic Oligomers -- 5.4.4 Identification of True Minima -- 5.4.5 Substituent Effects -- 5.5 Mixed Systems -- 5.5.1 Geometries -- 5.5.2 Energetics -- 5.5.3 Vibrational Spectra -- 5.5.4 Effects of Electron Correlation -- 5.5.5 Other Mixed Trimers -- 5.6 Summary -- 6 WEAK INTERACTIONS, IONIC H-BONDS, AND ION PAIRS.

6.1 Weak Acceptors -- 6.1.1 Dihalogens -- 6.1.2 CO -- 6.1.3 CO[sub(2)] -- 6.1.4 NNO -- 6.1.5 SO[sub(2)] -- 6.1.6 CCl[sub(2)] -- 6.2 C-H as Proton Donor -- 6.2.1 Alkynes -- 6.2.2 Alkanes -- 6.2.3 Metal Atoms as Acceptors -- 6.2.4 Hydride as Proton Acceptor -- 6.3 Symmetric Ionic Hydrogen Bonds -- 6.3.1 Hydrogen Bihalides -- 6.3.2 Comparison with Other Anionic H-bonds -- 6.3.3 Cationic H-bonds -- 6.3.4 Comparisons between Cations and Anions -- 6.3.5 Alkyl Substituents -- 6.3.6 Other Considerations -- 6.4 Asymmetric Ionic Systems -- 6.4.1 General Principles -- 6.4.2 Test of Quantitative Relationships -- 6.5 Syn-Anti Competition in Carboxylate -- 6.5.1 Ab Initio Calculations -- 6.5.2 Experimental Findings -- 6.5.3 Carboxylic Group -- 6.5.4 Solvent Effects -- 6.5.5 Resolution of the Question -- 6.6 Neutral versus Ion Pairs -- 6.6.1 Amine-Hydrogen Halide -- 6.6.2 Carboxyl/Carboxylate Equilibrium -- 6.6.3 Experimental Confirmation -- 6.6.4 Long Chains -- 6.7 Summary -- 6.7.1 Low Polarity of Acceptor -- 6.7.2 C-H Donors -- 6.7.3 Ionic H-Bonds -- 6.7.4 Neutral Versus Ion Pairs -- Index of Complexes -- Subject Index -- A -- B -- C -- D -- E -- F -- G -- H -- I -- L -- M -- N -- O -- P -- Q -- R -- S -- T -- V -- W -- Z.