The 13 C cross-polarization magic angle spinning NMR spectra of N-( ) indicate a keto-hydroxy tautomerism of 1 but not of 2. This was confirmed by a single-crystal x-ray diffraction study of 1, which revealed that the two distinct molecules in the unit cell are linked by intermolecular hydrogen bon
The Hydrogen Bond in the Solid State
β Scribed by Thomas Steiner
- Publisher
- John Wiley and Sons
- Year
- 2002
- Tongue
- English
- Weight
- 497 KB
- Volume
- 41
- Category
- Article
- ISSN
- 0044-8249
No coin nor oath required. For personal study only.
β¦ Synopsis
The hydrogen bond is the most important of all directional intermolecular interactions. It is operative in determining molecular conformation, molecular aggregation, and the function of a vast number of chemical systems ranging from inorganic to biological. Research into hydrogen bonds experienced a stagnant period in the 1980s, but re-opened around 1990, and has been in rapid development since then. In terms of modern concepts, the hydrogen bond is understood as a very broad phenomenon, and it is accepted that there are open borders to other effects. There are dozens of different types of X-H.A hydrogen bonds that occur commonly in the condensed phases, and in addition there are innumerable less common ones. Dissociation energies span more than two orders of magnitude (about 0.2-40 kcal mol(-1)). Within this range, the nature of the interaction is not constant, but its electrostatic, covalent, and dispersion contributions vary in their relative weights. The hydrogen bond has broad transition regions that merge continuously with the covalent bond, the van der Waals interaction, the ionic interaction, and also the cation-pi interaction. All hydrogen bonds can be considered as incipient proton transfer reactions, and for strong hydrogen bonds, this reaction can be in a very advanced state. In this review, a coherent survey is given on all these matters.
π SIMILAR VOLUMES
The inΓuence of hydrogen bonding (HB) on the 13C chemical shift tensors in four solid amino acids was studied by the ab initio gauge-included atomic orbital (GIAO) approach. The results of the present calculations were compared with those predicted previously and with the experimentally observed shi