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14-September-2008 18:38:49 - bond In chemistry, a dihydrogen bond is a kind of hydrogen bond, an interaction between a metal hydride bond and an OH or NH group or another proton donor. The first example of this phenomenon is cred to Brown and Heseltine.1 They observed intense absorption bands in the IR bands at 3300 and 3210 cm-1 for a solution of CH32NHBH3. The higher energy band is assigned to a normal N-H vibration whereas the lower energy band is assigned to the same bond, which is interacting with the B-H. Upon dilution of the solution, the 3300 cm-1 band increased in intensity and the 3210 cm-1 band decreased, indicative of intermolecular association. Interest in dihydrogen bonding was reignited upon the crystallographic characterization of the molecule H3NBH3. In this molecule, like the one studied by Brown and Hazeltine, the hydrogen atoms on nitrogen have a partial positive charge, denoted Hδ+, and the hydrogen atoms on boron have a partial negative charge, often denoted Hδ-.2 In other words, the amine is protic acid and the borane end is hydridic. The resulting B-H...H-N attractions stabilize the molecule as a solid. In contrast, the related substance ethane, H3CCH3, is a gas with a boiling point 285 °C lower. Because two hydrogen atoms are involved, this is termed a dihydrogen bond. Formation of a dihydrogen bond is assumed to precede formation of H2 from the reaction of a hydride and a protic acid. A very short dihydrogen bond is observed in NaBH4.2H2O with H---H contacts of 1.79, 1.86, and 1.94 Å. 3 This kind of H---H interaction is distinct from the H---H bonding interaction in transition metal complexes having dihydrogen bound to a metal.4 Another so-called hydrogen hydrogen bond is postulated to exist in certain compounds between two neutral non-bonding hydrogen atoms. References ^ Brown, M. P.; Heseltine, R. W. Co-ordinated BH3 as a proton acceptor group in hydrogen bonding Chemical Communications 1968, page 1551-2. DOI: 10.1039/C19680001551 ^ A New Intermolecular Interaction: Unconventional Hydrogen Bonds with Element-Hydride Bonds as Proton Acceptor Crabtree, R. H.; Siegbahn, P. E. M.; Eisenstein, O.; Rheingold, A. L.; Koetzle, T. F. Acc. Chem. Res. 1996, 297, 348 - 354. ^ Custelcean, R.; Jackson, J. E. Dihydrogen Bonding: Structures, Energetics, and Dynamics Chemical Reviews 2001, volume 101, page 1963-1980. ^ Kubas, G. J., Metal Dihydrogen and σ-Bond Complexes, Kluwer Academic/Plenum Publishers: New York, 2001. v d e Chemical bonds Strong Covalent bonds Antibonding Sigma bonds: 3c-2e bent bond · 3c-4e Hydrogen bond, Dihydrogen bond, Agostic interaction · 4c-2e Pi bonds: π backbonding · Conjugation · Hyperconjugation · Aromaticity · Metal aromaticity Delta bond: Quadruple bond · Quintuple bond · Sextuple bond Coordinate covalent bond · Hapticity Ionic bonds Cation-pi interaction · Salt bridge Metallic bonds Metal aromaticity Weak Hydrogen bond Dihydrogen bond · Dihydrogen complex · Low-barrier hydrogen bond · Symmetric hydrogen bond · Hydrophile Other noncovalent van der Waals force · Mechanical bond · Halogen bond · Aurophilicity · Intercalation · Stacking · Entropic force · Chemical polarity other Disulfide bond · Peptide bond · Phosphodiester bond Note: the weakest strong bonds are not necessarily stronger than the strongest weak bonds Retrieved from http://en..org/wiki/Dihydrogen_bond Categories: Chemical bonding Views Article Discussion this page History Personal tools Log in / create account Navigation Main page Contents Featured content Current events Random article Search Go Search Interaction Community portal Recent changes Contact Donate to Help Toolbox What links here Related changes Upload file Special pages Printable version Permanent link Cite this page Languages العربية Français 한국어 日本語 中文 This page was last modified on 7 August 2008, at 17:00
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So many of us do not eat a balanced diet, get enough sleep, have too much stress, or are impacted with toxins and pollutants. Drinking 2 ounces of MonaVie twice a day will help your body detoxify as well as build your immune system. Its the smartest thing you can do for yourself, so start today. Buying MonaVie through our company guarantees you support 7 days a week and, if you would like to share MonaVie with your family and friends we will guide you from start to finish.
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