Entrance channel complexes of cationic aromatic SN2 reactions: IR spectra of fluorobenzene+–(H2O)n clusters
TL;DR: In this paper, microhydrated fluorobenzene cation clusters were characterized by IR photodissociation spectra in the O-H stretch range and UB3LYP/6-31G* calculations.
About: This article is published in Chemical Physics Letters.The article was published on 2005-05-02. It has received 25 citations till now. The article focuses on the topics: Fluorobenzene.
Citations
More filters
TL;DR: The new and exciting techniques of infrared consequence spectroscopy of gaseous ions are reviewed and this review mainly covers the topics with which the author has been directly involved in research: structures of proton-bound dimers, protonated amino acids and DNA bases, amino acid andDNA bases bound to metal ions and, more recently, solvated ionic complexes.
Abstract: In this article, the new and exciting techniques of infrared consequence spectroscopy (sometimes called action spectroscopy) of gaseous ions are reviewed. These techniques include vibrational predissociation spectroscopy and infrared multiple photon dissociation spectroscopy and they typically complement one another in the systems studied and the information gained. In recent years infrared consequence spectroscopy has provided long-awaited direct evidence into the structures of gaseous ions from organometallic species to strong ionic hydrogen bonded structures to large biomolecules. Much is being learned with respect to the structures of ions without their stabilizing solvent which can be used to better understand the effect of solvent on their structures. This review mainly covers the topics with which the author has been directly involved in research: structures of proton-bound dimers, protonated amino acids and DNA bases, amino acid and DNA bases bound to metal ions and, more recently, solvated ionic complexes. It is hoped that this review reveals the impact that infrared consequence spectroscopy has had on the field of gaseous ion chemistry.
197 citations
TL;DR: In this article, the fundamental importance of non-covalent interactions in nature by illustrating specific examples from chemistry, physics, and the biosciences is discussed, and a review with 270 references is presented.
Abstract: The review focusses on the fundamental importance of non-covalent interactions in nature by illustrating specific examples from chemistry, physics and the biosciences. Laser spectroscopic methods and both ab initio and molecular modelling procedures used for the study of non-covalent interactions in molecular clusters are briefly outlined. The role of structure and geometry, stabilization energy, potential and free energy surfaces for molecular clusters is extensively discussed in the light of the most advanced ab initio computational results for the CCSD(T) method, extrapolated to the CBS limit. The most important types of non-covalent complexes are classified and several small and medium size non-covalent systems, including H-bonded and improper H-bonded complexes, nucleic acid base pairs, and peptides and proteins are discussed with some detail. Finally, we evaluate the interpretation of experimental results in comparison with state of the art theoretical models: this is illustrated for phenol...Ar, the benzene dimer and nucleic acid base pairs. A review with 270 references.
182 citations
TL;DR: This review describes the development and application of a new experimental approach, namely, picosecond time-resolved pump-probe infrared spectroscopy of size- and isomer-selected aromatic clusters, in which for the first time the dynamics of a single individual solvent molecule can be followed in real time.
Abstract: Solvation processes play a crucial role in chemical reactions and biomolecular recognition phenomena. Although solvation dynamics of interfacial or biological water has been studied extensively in aqueous solution, the results are generally averaged over several solvation layers and the motion of individual solvent molecules is difficult to capture. This review describes the development and application of a new experimental approach, namely, picosecond time-resolved pump–probe infrared spectroscopy of size- and isomer-selected aromatic clusters, in which for the first time the dynamics of a single individual solvent molecule can be followed in real time. The intermolecular isomerization reaction is triggered by resonant photoionization (pump), and infrared photodissociation (probe) at variable delay generates the spectroscopic signature of salient properties of the reaction, including rates, yields, pathways, branching ratios of competing reactions, existence of reaction intermediates, occurrence of back ...
78 citations
TL;DR: In this article, the gas phase infrared spectrum (3250-3810 cm−1) of the singly hydrated ammonium ion, NH4+ + H2O, has been recorded by action spectroscopy of mass selected and isolated ions.
Abstract: The gas phase infrared spectrum (3250–3810cm−1) of the singly hydrated ammonium ion, NH4+(H2O), has been recorded by action spectroscopy of mass selected and isolated ions. The four bands obtained are assigned to N–H stretching modes and to O–H stretching modes. The N–H stretching modes observed are blueshifted with respect to the corresponding modes of the free NH4+ ion, whereas a redshift is observed with respect to the modes of the free NH3 molecule. The O–H stretching modes observed are redshifted when compared to the free H2O molecule. The asymmetric stretching modes give rise to rotationally resolved perpendicular transitions. The K-type equidistant rotational spacings of 11.1(2)cm−1 (NH4+) and 29(3)cm−1 (H2O) deviate systematically from the corresponding values of the free molecules, a fact which is rationalized in terms of a symmetric top analysis. The relative band intensities recorded compare favorably with predictions of high level ab initio calculations, except on the ν3(H2O) band for which th...
66 citations
TL;DR: In this paper, the ionisation-induced π→H site switching reaction in clusters of phenol solvated by rare gas ligands is characterized by electron impact infrared (EI-IR) photodissociation as well as nanosecond and picosecond time-resolved UV-UV-IR spectroscopy.
Abstract: The ionisation-induced π → H site switching reaction in clusters of phenol solvated by rare gas ligands, PhOH–Rg n (Rg = Ar and Kr, n = 1–3), is characterised by electron impact infrared (EI–IR) photodissociation as well as nanosecond and picosecond time-resolved UV–UV–IR spectroscopy. The EI–IR spectra of the PhOH+–Rg dimers demonstrate that the H-bound isomer is the most stable structure in the ground electronic state of the cation, in which the Rg atom forms a hydrogen bond to the OH group of PhOH+. The π-bound structure, in which the Rg ligand is attached to the aromatic ring, is also weakly detected as a less stable structure in the EI–IR spectrum. The IR spectra of the PhOH+–Rg dimers change drastically, when the cluster cations are generated by resonance-enhanced multiphoton ionisation (REMPI). The metastable π-bound structure becomes the major species and dominates the population. The picosecond time-resolved REMPI–IR spectra clearly demonstrate the initial population of the π-bound structure by i...
51 citations
References
More filters
Book•
01 Jun 1977
TL;DR: Localized Chemical bonding Delocalized Chemical Bonding Bonding Weaker than Covalent Stereochemistry Carbocations, Carbanions, Free Radicals, Carbenes and Nitrenes Mechanisms and Methods of Determining them Photochemistry Acids and Bases Effects of Structure on Reactivity Aliphatic Nucleophilic Substitution Aromatic Electrophilic Substitutes Aliphatically Electrophilic Substitution Free-Radical Substitution Addition to Carbon-Carbon Multiple Bonds Adding to Carbon Hetero Multiple Bonds Eliminations Rearrangements Ox
Abstract: Localized Chemical bonding Delocalized Chemical Bonding Bonding Weaker than Covalent Stereochemistry Carbocations, Carbanions, Free Radicals, Carbenes and Nitrenes Mechanisms and Methods of Determining Them Photochemistry Acids and Bases Effects of Structure on Reactivity Aliphatic Nucleophilic Substitution Aromatic Electrophilic Substitution Aliphatic Electrophilic Substitution Free-Radical Substitution Addition to Carbon-Carbon Multiple Bonds Addition to Carbon- Hetero Multiple Bonds Eliminations Rearrangements Oxidations and Reductions The Literature of Organic Chemistry Classifications of Reactions by Type of Compound Synthesized.
4,885 citations
TL;DR: In this paper, the available data on gas phase basicities and proton affinities of molecules are compiled and evaluated, and tables giving the molecules ordered according to proton affinity and (2) according to empirical formula, sorted alphabetically are provided.
Abstract: The available data on gas phase basicities and proton affinities of molecules are compiled and evaluated. Tables giving the molecules ordered (1) according to proton affinity and (2) according to empirical formula, sorted alphabetically are provided. The heats of formation of the molecules and the corresponding protonated species are also listed.
1,244 citations
TL;DR: In this paper, a comprehensive tabulation of the standard enthalpy change, ΔH°, entropy change ΔS°, and free energy change ΔG° for the formation of ion clusters from ion-molecule association reactions is given.
Abstract: A comprehensive tabulation of the standard enthalpy change, ΔH°, entropy change, ΔS°, and free energy change, ΔG°, for the formation of ion clusters from ion‐molecule association reactions is given. The experimental methods which are used to derive the data are briefly discussed. For some experiments, dissociation energies of ion clusters are reported and listed under the category of ΔH°. The relationship between ΔH° and dissociation energy is discussed in the text.
515 citations