W. Ronald Fawcett
- Published in print:
- 2004
- Published Online:
- November 2020
- ISBN:
- 9780195094329
- eISBN:
- 9780197560747
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780195094329.003.0009
- Subject:
- Chemistry, Physical Chemistry
Spectroscopy involves the study of the interactions of electromagnetic radiation with matter. In the case of liquids, radiation of a wide range of frequencies, and thus energies, has been used, all ...
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Spectroscopy involves the study of the interactions of electromagnetic radiation with matter. In the case of liquids, radiation of a wide range of frequencies, and thus energies, has been used, all the way from radio-frequency waves to X-rays. Experiments involving neutrons, which are associated with very short wavelengths, are also important. In the spectroscopic experiment the incident radiation may be either absorbed or scattered and the experimental information is obtained by examining the intensity and direction of the radiation after it has passed through the sample. Several spectroscopic techniques will be considered in this chapter. X-ray and neutron diffraction techniques are powerful tools for studying the structure of liquids and have been introduced in chapter 2. They may also be used to study the structure of solutions and determine distribution functions for both the solute and solvent. The feasibility of these experiments depends on the number of different nuclei involved in the system. UV-visible spectroscopy is mainly used to study electronic transitions in polyatomic species. These species are often complex ions formed between the electrolyte and the solvent, or between the cation and one or more anions. Vibrational spectroscopy involves electromagnetic radiation of lower energy, usually in the infrared region. It is used to study intramolecular vibrational modes and how they are altered by the environment in solution. It can also be used to study the bonds formed between solute and solvent in the solvation process. Finally, nuclear magnetic resonance spectroscopy and its application to the study of solvation will be discussed. This is a particularly powerful technique because it provides information about the environment of a given nucleus, and experiments specific to a given nucleus can be carried out provided the nucleus has a non-zero magnetic moment. Several other spectroscopic techniques are commonly used [G1] but those considered here provide a representative picture of what can be learnt from those experiments. One should remember that the atoms and molecules in liquids are not motionless but in a state of flux determined by the intermolecular interactions and temperature. From the study of microwave spectroscopy discussed in chapter 4, it was found that rotational diffusion processes in liquids are characterized by relaxation times the order of a few picoseconds.
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Spectroscopy involves the study of the interactions of electromagnetic radiation with matter. In the case of liquids, radiation of a wide range of frequencies, and thus energies, has been used, all the way from radio-frequency waves to X-rays. Experiments involving neutrons, which are associated with very short wavelengths, are also important. In the spectroscopic experiment the incident radiation may be either absorbed or scattered and the experimental information is obtained by examining the intensity and direction of the radiation after it has passed through the sample. Several spectroscopic techniques will be considered in this chapter. X-ray and neutron diffraction techniques are powerful tools for studying the structure of liquids and have been introduced in chapter 2. They may also be used to study the structure of solutions and determine distribution functions for both the solute and solvent. The feasibility of these experiments depends on the number of different nuclei involved in the system. UV-visible spectroscopy is mainly used to study electronic transitions in polyatomic species. These species are often complex ions formed between the electrolyte and the solvent, or between the cation and one or more anions. Vibrational spectroscopy involves electromagnetic radiation of lower energy, usually in the infrared region. It is used to study intramolecular vibrational modes and how they are altered by the environment in solution. It can also be used to study the bonds formed between solute and solvent in the solvation process. Finally, nuclear magnetic resonance spectroscopy and its application to the study of solvation will be discussed. This is a particularly powerful technique because it provides information about the environment of a given nucleus, and experiments specific to a given nucleus can be carried out provided the nucleus has a non-zero magnetic moment. Several other spectroscopic techniques are commonly used [G1] but those considered here provide a representative picture of what can be learnt from those experiments. One should remember that the atoms and molecules in liquids are not motionless but in a state of flux determined by the intermolecular interactions and temperature. From the study of microwave spectroscopy discussed in chapter 4, it was found that rotational diffusion processes in liquids are characterized by relaxation times the order of a few picoseconds.
GAUTAM R. DESIRAJU and THOMAS STEINER
- Published in print:
- 2001
- Published Online:
- January 2010
- ISBN:
- 9780198509707
- eISBN:
- 9780191708206
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198509707.003.0001
- Subject:
- Physics, Crystallography: Physics
The hydrogen bond is a unique phenomenon in both structural chemistry and structural biology. Its fundamental importance lies in its role in molecular association. Its functional importance stems ...
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The hydrogen bond is a unique phenomenon in both structural chemistry and structural biology. Its fundamental importance lies in its role in molecular association. Its functional importance stems from both thermodynamic and kinetic reasons. In supramolecular chemistry, the hydrogen bond is able to control and direct the structures of molecular assemblies because it is sufficiently strong and sufficiently directional. In this introductory chapter, a historical background of the hydrogen bond is presented. The geometrical parameters and definitions of a hydrogen bond are then discussed, along with energetic parameters and definitions, the weak or non-conventional hydrogen bond, classification of hydrogen bonds, the nature of the hydrogen bond interaction and its limits, differences between strong and weak hydrogen bonds, and methods of studying weak hydrogen bonds including crystal structure analysis, vibrational spectroscopy, gas-phase rotational spectroscopy, and computation.Less
The hydrogen bond is a unique phenomenon in both structural chemistry and structural biology. Its fundamental importance lies in its role in molecular association. Its functional importance stems from both thermodynamic and kinetic reasons. In supramolecular chemistry, the hydrogen bond is able to control and direct the structures of molecular assemblies because it is sufficiently strong and sufficiently directional. In this introductory chapter, a historical background of the hydrogen bond is presented. The geometrical parameters and definitions of a hydrogen bond are then discussed, along with energetic parameters and definitions, the weak or non-conventional hydrogen bond, classification of hydrogen bonds, the nature of the hydrogen bond interaction and its limits, differences between strong and weak hydrogen bonds, and methods of studying weak hydrogen bonds including crystal structure analysis, vibrational spectroscopy, gas-phase rotational spectroscopy, and computation.
GAUTAM R. DESIRAJU and THOMAS STEINER
- Published in print:
- 2001
- Published Online:
- January 2010
- ISBN:
- 9780198509707
- eISBN:
- 9780191708206
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198509707.003.0002
- Subject:
- Physics, Crystallography: Physics
Many, if not all, attributes of the classical hydrogen bond, X-H···A, would seem to derive from the fact that X and A are electronegative elements and from the unique electronic configuration of the ...
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Many, if not all, attributes of the classical hydrogen bond, X-H···A, would seem to derive from the fact that X and A are electronegative elements and from the unique electronic configuration of the H atom that permits close approaches of the X and A atoms. Indeed, it is only this combination of circumstances that makes this type of association possible, thus rendering the term ‘hydrogen bond’ so appropriate. The difference between strong and weak hydrogen bonding lies in the fact that in the latter situation, one or both of the atoms X and A are of moderate electronegativity only. This chapter looks at archetypes of the weak hydrogen bond -C-H···O and C-H···N interactions in organic and organometallic systems, along with the general properties of the weak hydrogen bond, vibrational spectroscopy of the weak hydrogen bond, reduction of thermal vibrations, computatioaal studies and hydrogen bond energies, cooperativity, hardness and softness, and weak hydrogen bonds in liquids and solution.Less
Many, if not all, attributes of the classical hydrogen bond, X-H···A, would seem to derive from the fact that X and A are electronegative elements and from the unique electronic configuration of the H atom that permits close approaches of the X and A atoms. Indeed, it is only this combination of circumstances that makes this type of association possible, thus rendering the term ‘hydrogen bond’ so appropriate. The difference between strong and weak hydrogen bonding lies in the fact that in the latter situation, one or both of the atoms X and A are of moderate electronegativity only. This chapter looks at archetypes of the weak hydrogen bond -C-H···O and C-H···N interactions in organic and organometallic systems, along with the general properties of the weak hydrogen bond, vibrational spectroscopy of the weak hydrogen bond, reduction of thermal vibrations, computatioaal studies and hydrogen bond energies, cooperativity, hardness and softness, and weak hydrogen bonds in liquids and solution.
Wai-Kee Li, Yu-San Cheung, Kendrew Kin Wah Mak, and Thomas Chung Wai Mak
- Published in print:
- 2012
- Published Online:
- December 2013
- ISBN:
- 9780199658497
- eISBN:
- 9780191775055
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199658497.003.0008
- Subject:
- Physics, Crystallography: Physics, Condensed Matter Physics / Materials
This chapter presents twenty-one problems covering the subject of vibrational spectroscopy, along with the corresponding solutions.
This chapter presents twenty-one problems covering the subject of vibrational spectroscopy, along with the corresponding solutions.
Wai-Kee Li, Yu-San Cheung, Kendrew Kin Wah Mak, and Thomas Chung Wai Mak
- Published in print:
- 2012
- Published Online:
- December 2013
- ISBN:
- 9780199658497
- eISBN:
- 9780191775055
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199658497.001.0001
- Subject:
- Physics, Crystallography: Physics, Condensed Matter Physics / Materials
This book consists of over 300 problems (and their solutions) in structural inorganic chemistry. The topics covered are: atomic and molecular electronic states, atomic orbitals, hybrid orbitals, ...
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This book consists of over 300 problems (and their solutions) in structural inorganic chemistry. The topics covered are: atomic and molecular electronic states, atomic orbitals, hybrid orbitals, molecular symmetry, molecular geometry and bonding, crystal field theory, molecular orbital theory, vibrational spectroscopy, and crystal structure. The central theme running through these topics is symmetry, molecular or crystalline. The problems collected in this volume originate in examination papers and take-home assignments that have been part of the teaching of the book's two senior authors at The Chinese University of Hong Kong over the past four decades.Less
This book consists of over 300 problems (and their solutions) in structural inorganic chemistry. The topics covered are: atomic and molecular electronic states, atomic orbitals, hybrid orbitals, molecular symmetry, molecular geometry and bonding, crystal field theory, molecular orbital theory, vibrational spectroscopy, and crystal structure. The central theme running through these topics is symmetry, molecular or crystalline. The problems collected in this volume originate in examination papers and take-home assignments that have been part of the teaching of the book's two senior authors at The Chinese University of Hong Kong over the past four decades.
Wai-Kee Li, Hung Kay Lee, Dennis Kee Pui Ng, Yu-San Cheung, Kendrew Kin Wah Mak, and Thomas Chung Wai Mak
- Published in print:
- 2018
- Published Online:
- January 2019
- ISBN:
- 9780198823902
- eISBN:
- 9780191862724
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198823902.001.0001
- Subject:
- Physics, Crystallography: Physics, Condensed Matter Physics / Materials
The First Edition of this book, which appeared in 2013, serves as a problem text for Part I (Fundamentals of Chemical Bonding) and Part II (Symmetry in Chemistry) of the book Advanced Structural ...
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The First Edition of this book, which appeared in 2013, serves as a problem text for Part I (Fundamentals of Chemical Bonding) and Part II (Symmetry in Chemistry) of the book Advanced Structural Inorganic Chemistry published by Oxford University Press in 2008. A Chinese edition was published by Peking University Press in August in the same year. Since then the authors have received much feedback from users and reviewers, which prompted them to prepare a Second Edition for students ranging from freshmen to senior undergraduates who aspire to attend graduate school after finishing their first degree in Chemistry. Four new chapters are added to this expanded Second Edition, which now contains over 400 problems and their solutions. The topics covered in 13 chapters follow the sequence: electronic states and configurations of atoms and molecules, introductory quantum chemistry, atomic orbitals, hybrid orbitals, molecular symmetry, molecular geometry and bonding, crystal field theory, molecular orbital theory, vibrational spectroscopy, crystal structure, transition metal chemistry, metal clusters: bonding and reactivity, and bioinorganic chemistry. The problems collected in this volume originate from examination papers and take-home assignments that have been part of the teaching program conducted by senior authors at The Chinese University of Hong Kong over nearly a half-century. Whenever appropriate, source references in the chemical literature are given for readers who wish to delve deeper into the subject. Eight Appendices and a Bibliography listing 157 reference books are provided to students and teachers who wish to look up comprehensive presentations of specific topics.Less
The First Edition of this book, which appeared in 2013, serves as a problem text for Part I (Fundamentals of Chemical Bonding) and Part II (Symmetry in Chemistry) of the book Advanced Structural Inorganic Chemistry published by Oxford University Press in 2008. A Chinese edition was published by Peking University Press in August in the same year. Since then the authors have received much feedback from users and reviewers, which prompted them to prepare a Second Edition for students ranging from freshmen to senior undergraduates who aspire to attend graduate school after finishing their first degree in Chemistry. Four new chapters are added to this expanded Second Edition, which now contains over 400 problems and their solutions. The topics covered in 13 chapters follow the sequence: electronic states and configurations of atoms and molecules, introductory quantum chemistry, atomic orbitals, hybrid orbitals, molecular symmetry, molecular geometry and bonding, crystal field theory, molecular orbital theory, vibrational spectroscopy, crystal structure, transition metal chemistry, metal clusters: bonding and reactivity, and bioinorganic chemistry. The problems collected in this volume originate from examination papers and take-home assignments that have been part of the teaching program conducted by senior authors at The Chinese University of Hong Kong over nearly a half-century. Whenever appropriate, source references in the chemical literature are given for readers who wish to delve deeper into the subject. Eight Appendices and a Bibliography listing 157 reference books are provided to students and teachers who wish to look up comprehensive presentations of specific topics.
Bruce C. Bunker and William H. Casey
- Published in print:
- 2016
- Published Online:
- November 2020
- ISBN:
- 9780199384259
- eISBN:
- 9780197562987
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780199384259.003.0008
- Subject:
- Chemistry, Inorganic Chemistry
Water is one of the most complex fluids on Earth. Even after intense study, there are many aspects regarding the structure, properties, and chemistry of water that are not well understood. In this ...
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Water is one of the most complex fluids on Earth. Even after intense study, there are many aspects regarding the structure, properties, and chemistry of water that are not well understood. In this chapter, we highlight the attributes of water that dictate many of the reactions that take place between water and oxides. We start with a single water molecule and progress to water clusters, then finally to extended liquid and solid phases. This chapter provides a baseline for evaluating what happens when water encounters simple ions, soluble oxide complexes called hydrolysis products, and extended oxide phases. The primary phenomenon highlighted in this chapter is hydrogen bonding. Hydrogen bonding dominates the structure and properties of water and influences many water–oxide interactions. A single water molecule has eight valence electrons around a central oxygen anion. These electrons are contained in four sp3-hybridized molecular orbitals arranged as lobes that extend from the oxygen in a tetrahedral geometry. Each orbital is occupied by two electrons. Two of the lobes are bonded to protons; the other two lobes are referred to as lone pairs of electrons. The H–O–H bond angle of 104.5° is close to the tetrahedral angle of 109.5°. The O–H bond length in a single water molecule is 0.96 ?. It is important to recognize that this bond length is really a measure of the electron density associated with the oxygen lone pair bonded to the proton. This is because a proton is so incredibly small (with an ionic radius of only 1.3.10–5 ?) that it makes no contribution to the net bond length. The entire water molecule has a hard sphere diameter of 2.9 ?, which is fairly typical for an oxygen anion. This means the unoccupied lone pairs are distended relative to the protonated lone pairs, extending out to roughly 1.9 ?. The unequal distribution of charges introduces a dipole within the water molecule that facilitates electrostatic interactions with other molecules.
Less
Water is one of the most complex fluids on Earth. Even after intense study, there are many aspects regarding the structure, properties, and chemistry of water that are not well understood. In this chapter, we highlight the attributes of water that dictate many of the reactions that take place between water and oxides. We start with a single water molecule and progress to water clusters, then finally to extended liquid and solid phases. This chapter provides a baseline for evaluating what happens when water encounters simple ions, soluble oxide complexes called hydrolysis products, and extended oxide phases. The primary phenomenon highlighted in this chapter is hydrogen bonding. Hydrogen bonding dominates the structure and properties of water and influences many water–oxide interactions. A single water molecule has eight valence electrons around a central oxygen anion. These electrons are contained in four sp3-hybridized molecular orbitals arranged as lobes that extend from the oxygen in a tetrahedral geometry. Each orbital is occupied by two electrons. Two of the lobes are bonded to protons; the other two lobes are referred to as lone pairs of electrons. The H–O–H bond angle of 104.5° is close to the tetrahedral angle of 109.5°. The O–H bond length in a single water molecule is 0.96 ?. It is important to recognize that this bond length is really a measure of the electron density associated with the oxygen lone pair bonded to the proton. This is because a proton is so incredibly small (with an ionic radius of only 1.3.10–5 ?) that it makes no contribution to the net bond length. The entire water molecule has a hard sphere diameter of 2.9 ?, which is fairly typical for an oxygen anion. This means the unoccupied lone pairs are distended relative to the protonated lone pairs, extending out to roughly 1.9 ?. The unequal distribution of charges introduces a dipole within the water molecule that facilitates electrostatic interactions with other molecules.
