A- and B-type hydrogen bond modifications of potassium hydrogen tartronate
ACCORDING to Speakman1 two types of intermolecular hydrogen bonds between carboxyl groups can be discerned in the crystal structures of acid salts of carboxylic acids. The first, type B, occurs when two carboxyl groups are not symmetry related, and have structural differences sufficient to characterise them, separately, as unionised (−CO2H) and ionised (−CO2−). Thus, any hydrogen bond between these groups must be asymmetric. The second, type A, occurs when two carboxyl groups are related by a symmetry element of the crystal, so that they are effectively equivalent. Thus any hydrogen bond between the groups must be, at least formally, symmetrical.
Infrared spectra of strongly hydrogen-bonded systems
In the early spectroscopic work on hydrogen bonding the attention of the investigators was mainly directed to the shifts of the stretching bands. lnterest was later extended to the intensity increase and broadening. With stronger hydrogen bonds and better resolution coming into the field the problern of the irregular band shapes and extra peaks arose. Whereas the band shifts and in tensi ty changes. are explained by curren t theories of hydrogen bonding there are still controversies about the breadth and the exact origin of the structure of bands due to the stretching vibration of
Beings of nature and reason: mythological masculinities in early 18th-century French art and visual culture
Statement of Originality Acknowledgments List of Illustrations Introduction 11 Chapter One Of Myth and Men 27 Chapter Two In the Likeness of Bacchus 62 Chapter Three Venus and a Satyr 97 Chapter Four Pan and Syrinx 141 Chapter Five Marsyas Flayed by the Order of Apollo 175 Conclusion 212 Catalogue of Images 227 Bibliography 300