Extensive calculations on hydrogen bonded systems were carried out using the improved MM3 directional hydrogen bond potential. The resulting total function was reoptimized. Comparisons of the hydrogen bonding potential ลฝ UU . ลฝ . function from ab initio calculations MP2r6-31G ; the original MM3 89 ;
Hydrogen bonding in MM2
โ Scribed by Norman L. Allinger; Randall A. Kok; Mita R. Imam
- Publisher
- John Wiley and Sons
- Year
- 1988
- Tongue
- English
- Weight
- 496 KB
- Volume
- 9
- Category
- Article
- ISSN
- 0192-8651
No coin nor oath required. For personal study only.
โฆ Synopsis
Hydrogen bonding is qualitatively accounted for in the early versions of the MM2 program, but not quantitatively. Experimentally, the hydrogen bonds are somewhat shorter and stronger than calculated by MM2. This has been corrected now in MM2(87), by reducing the van der Waals radius of the hydrogen involved in hydrogen bonding for that interaction only, and by increasing the van der Waals' attraction between the hydrogen and the various electronegative atoms to which it can hydrogen bond by about 1-3 kcal/mol, depending on the particular atoms involved. It is now possible to reproduce reasonably well ab initio calculations on simple amides and the methanol dimer, and experimental data on compounds in which a hydroxyl hydrogen is hydrogen bonded to an alcohol, an alkyl chloride, or to a carbon-carbon double bond.
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The hydrogen-bond connectivity in 39 sulfonamide crystal structures has been deciphered and described using graph set notation. The hydrogen-bond connectivity observed is used to gain information on hydrogen-bond preferences of speciยฎc donor and acceptor atoms of related sulfonamide molecules. The a