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Acid Dimer (acid + dimer)
Selected AbstractsStructure of the Boronic Acid Dimer and the Relative Stabilities of Its ConformersCHEMINFORM, Issue 48 2006Joseph D. Larkin Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Hydrogen bonds assisted by ,-electron delocalization , the influence of external intermolecular interactions on dimer of formic acidJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 7-8 2008awomir J. Grabowski Abstract MP2 and DFT calculations with the use of 6-311++G(d,p) basis set were carried out to study formic acid dimer as well as this species interacting with additional Lewis acids such as HF, Li+ and Na+. These Lewis acids were positioned near carbonyl or hydroxyl oxygen atoms and their influence on geometrical and other parameters of formic acid dimer was analysed. Additionally the ,quantum theory of atoms in molecules' (QTAIM) was applied as well as the ,natural bond orbitals' (NBO) method. Numerous correlations between geometrical, QTAIM and energetic parameters were found. It was found that ,-electron delocalization is not always connected with the enhancement of H-bond strength. Copyright © 2008 John Wiley & Sons, Ltd. [source] Structure and hydrogen bonding in 2,4-dihydroxybenzoic acid at 90, 100, 110 and 150,K; a theoretical and single-crystal X-ray diffraction studyACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2007Andrew Parkin A new polymorph of 2,4-dihydroxybenzoic acid is reported. The structure was characterized by multiple-temperature X-ray diffraction and solid-state DFT computations. The material shows a geometric pattern of hydrogen bonding consistent with cooperativity between the intermolecular carboxylic acid dimer and intramolecular hydrogen bonds. The presence of proton disorder within this hydrogen-bond system, which would support such a cooperative model, was not fully ruled out by the initial X-ray studies. However, solid-state calculations on the three possible end-point tautomers indicate that the dominant crystallographically observed configuration is substantially lower in energy than the other tautomers (by at least 9,kJ,mol,1), indicating that no disorder should be expected. It is therefore concluded that no disorder is observed either in the intra- or intermolecular hydrogen bonds of the title compound and that the cooperativity between the hydrogen bonds is not present within the temperature range studied. [source] 6-(2-Chloroacetamido)hexanoic acidACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2006Carolina Gastone Crystals of the title compound, C8H14ClNO3, belong to the space group Cc and are characterized by an asymmetric unit containing two molecules, both with a twisted conformation. The molecular packing is stabilized by N,H,O=C hydrogen bonds between the amide groups of molecules with the same conformation. In addition, hydrogen-bonded cyclic carboxylic acid dimers are established between molecules with a different conformation. The ClCH2,CONH bond has a cis conformation in order to favour an intramolecular Cl,HN electrostatic interaction. Weak intra- and intermolecular CH2,O=C interactions are also present. [source] | ||||||||||