Dihydrogen Bond: Principles, Experiments, and Applications Book

Preface     xi
Introduction: Weak Noncovalent Interactions     1
References     4
Brief Summary of Hydrogen-Bonded Systems: Definitions and General View     6
Conventional Hydrogen Bonds: Theoretical and Experimental Criteria of Hydrogen Bond Formation     6
Energy and Geometry of Conventional Hydrogen Bonds     11
Cooperative and Anticooperative Energy Effects in Systems with Classical Hydrogen Bonds     14
Dynamics of Classical Hydrogen Bonds     15
Nonconventional Hydrogen Bonds as a Part of Hydrogen-Bonded Systems: Definition and Classification     20
Difference Between Hydrogen and Chemical Bonds     24
Concluding Remarks     25
References     26
Concept of Dihydrogen Bonding     28
General View: From an H[subscript 2] Molecule to a Dihydrogen Bond via a Dihydrogen Ligand     29
The Nature of Dihydrogen Bonding: The Topology of Electron Density and Contributions to Total Bonding Energy     36
Scalar Spin-Spin Coupling Through Dihydrogen Bonds as Evidence of Their Partly Covalent Character     44
Field Effects on Dihydrogen Bonding     48
Pressure Effects on Dihydrogen Bonding     51
Difference Between Hydrogen and Dihydrogen Bonds     52
Concluding Remarks     54
References     54
How to Find a Dihydrogen Bond: Experimental Criteria of Dihydrogen Bond Formation     56
Dihydrogen-Bonded Complexes in the Solid State: X-Ray and Neutron Diffraction Evidence     57
Topology of Electron Density in Dihydrogen-Bonded Systems from Diffraction Data     63
Gas-Phase Experiments with Dihydrogen-Bonded Complexes     65
Experiments with Dihydrogen-Bonded Complexes in Solutions     69
IR Spectral Criteria for the Formation of Dihydrogen-Bonded Complexes in Solutions     69
How to Determine the Stoichiometry of Dihydrogen-Bonded Complexes in Solution by IR Spectroscopy     73
Energy Parameters of Dihydrogen-Bonded Complexes from IR Spectra in Solution     73
[superscript 1]H Nuclear Magnetic Resonance Evidence for Dihydrogen Bonding in Solution     75
Energy Parameters of Dihydrogen Bonds in Solution from [superscript 1]H NMR     80
Concluding Remarks     82
References     83
Intramolecular Dihydrogen Bonds: Theory and Experiment     85
Weak Intramolecular Bonding: C-H...H-C in Systems with Slightly Polarized Bonds CH     86
Intramolecular Dihydrogen Bonds in Solid Amino Acids: C-H Bonds as Weak Proton Acceptors     89
Intramolecular Dihydrogen Bonds: C-H...H-B      92
Intramolecular Bonds: N-H...H-B and O-H...H-B     94
Intramolecular Dihydrogen Bonds in Metal Hydride Complexes     98
Intramolecular Dihydrogen Bonds in Metal Hydride Clusters     103
Connection Between Intramolecular Dihydrogen Bonding and Dehydrogenation Reactions     106
Concluding Remarks     110
References     110
Intermolecular Dihydrogen-Bonded Complexes: From Groups 1A-4A to Xenon Dihydrogen-Bonded Complexes     112
Group 1A: Dihydrogen Bonds X-H...H-Li and X-H...H-Na-(X = F, Cl, NH[subscript 3], CN, NC, HO, HS, ClCC, FCC, HCC)     112
Group 2A: Dihydrogen Bonds X-H...H-Mg and X-H...H-Be-(X = F, Cl, Br, NH[subscript 3], NNN, CN, NC, ClCC, FCC, HCC, CH[subscript 3]CC, F[subscript 2]Be, FKr, FAr)     119
Group 3A: Dihydrogen Bonds X-H...H-B, X-H...H-Al, and X-H...H-Ga [X = FCC, HCC, LiCC, CH3OH, Pr[superscript i]OH, CF[subscript 3]OH, CF[subscript 3]CH[subscript 2]OH, CFH[subscript 2]CH[subscript 2]OH, (CF[subscript 3])[subscript 2]CHOH, (CF[subscript 3])[subscript 3]COH, CN, CH[subscript 3], Indole, Imidazole, Pyrrole, FKr, FAr]     128
Hydrides of the Elements in Group 4A Acting as Proton Acceptors and Proton Donors: Very Weak Dihydrogen Bonds     137
Bonds C-H, Si-H, and Ge-H in Dihydrogen Bonding     137
H-H Bonding     143
Xenon Dihydrogen-Bonded Complexes     144
Concluding Remarks      147
References     148
Intermolecular Dihydrogen Bonding in Transition Metal Hydride Complexes     150
Theoretical View of Intermolecular Dihydrogen Bonding in Transition Metal Hydride Complexes     156
Energy and Structural Parameters of Intermolecular Dihydrogen-Bonded Complexes in Solutions of Transition Metal Hydrides     159
Unusual M-H...H-M Bonds     163
Concluding Remarks     165
References     165
Correlation Relationships for Intermolecular Dihydrogen Bonds     167
General Classification of Negatively Polarized Hydrogen Atoms as Proton-Accepting Sites: Basicity Factors     167
Correlation Relationships: Energy of Formation Versus H...H Distance Established for Intermolecular Dihydrogen Bonds     171
Correlation Relationships Between Energetic, Structural, and Electron Density Parameters of Intermolecular Dihydrogen-Bonded Complexes     175
Proton Affinity of Hydridic Hydrogens     178
Concluding Remarks     181
References     181
Perspectives on Dihydrogen Bonding in Supramolecular Chemistry and Crystal Engineering     183
Concluding Remarks     191
References     191
Dihydrogen Bonds as Intermediates in Intermolecular Proton Transfer Reactions     192
Methods Employed in Kinetic Studies of Proton Transfer to Hydridic Hydrogens     193
Electrochemical Experiments     193
Time-Dependent IR Spectra     194
NMR Spectra     194
Stopped-Flow Experiments     196
Theoretical Approaches     197
Proton Transfer to a Hydridic Hydrogen in the Solid State     199
Proton Transfer to a Hydride Ligand in Solutions of Transition Metal Hydride Complexes: Theory and Experiment     202
Kinetic Experiments with Proton Transfer to a Hydride Ligand in Solution     204
Proton-Hydride Exchange as a Measure of Proton Transfer to a Hydride Ligand in Solution     211
Proton Transfer to a Hydride Ligand in Solution: Experimental Observation of Intermediates     214
Energy Profile of Proton Transfer to a Hydride Ligand in Solution     216
Energy, Intermediates, and Transition States in Intermolecular Proton Transfer to Hydridic Hydrogens: Theoretical Studies     219
Proton Transfer to Hydrides of the Group 3A Elements     220
Theory of Proton Transfer to Transition Metal Hydrides     223
Concluding Remarks     227
References     228
General Conclusions     230
How Short or Long Can Dihydrogen Bonds Be?     230
Specific Influence of the Environment on Dihydrogen Bonding     233
References     235
Index     237