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Bifurcated H-bond systems are common in alpha-helical transmembrane proteins between the backbone amide C=O of residue i as the H-bond acceptor and two H-bond donors from residue i + 4: the backbone amide N−H and a side-chain hydroxyl or thiol H +. The energy preference of the bifurcated H-bond hydroxyl or thiol system is -3.4 kcal/mol or -2. ...
A coordinate covalent bond is a covalent bond in which the two shared bonding electrons are from the same one of the atoms involved in the bond. For example, boron trifluoride (BF 3) and ammonia (NH 3) form an adduct or coordination complex F 3 B←NH 3 with a B–N bond in which a lone pair of electrons on N is shared with an empty atomic ...
A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. [1] When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an energy change as new products are generated.
As one might expect, the stronger the non-covalent interactions present for a substance, the higher its boiling point. For example, consider three compounds of similar chemical composition: sodium n-butoxide (C 4 H 9 ONa), diethyl ether (C 4 H 10 O), and n-butanol (C 4 H 9 OH). Figure 8. Boiling points of 4-carbon compounds
Chemical compounds have a unique and defined chemical structure held together in a defined spatial arrangement by chemical bonds. Chemical compounds can be molecular compounds held together by covalent bonds, salts held together by ionic bonds, intermetallic compounds held together by metallic bonds, or the subset of chemical complexes that are ...
The [W(PR 3) 2 (CO) 3 (H 2)] complex was the first well characterized example of both a non-classical dihydride and sigma-bond complex in general. [ 16 ] [ 17 ] X-ray diffraction is generally insufficient to locate hydrides in crystal structures and thus their location must be assumed.
By some definitions, "organic" compounds are only required to contain carbon. However, most of them also contain hydrogen, and because it is the carbon-hydrogen bond that gives this class of compounds most of its particular chemical characteristics, carbon-hydrogen bonds are required in some definitions of the word "organic" in chemistry. [12]
One common form of polar interaction is the hydrogen bond, which is also known as the H-bond. For example, water forms H-bonds and has a molar mass M = 18 and a boiling point of +100 °C, compared to nonpolar methane with M = 16 and a boiling point of –161 °C.