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Clar's rule states that for a benzenoid polycyclic aromatic hydrocarbon (i.e. one with only hexagonal rings), the resonance structure with the largest number of disjoint aromatic π-sextets is the most important to characterize its chemical and physical properties. Such a resonance structure is called a Clar structure. In other words, a ...
Contributing structures of the carbonate ion. In chemistry, resonance, also called mesomerism, is a way of describing bonding in certain molecules or polyatomic ions by the combination of several contributing structures (or forms, [1] also variously known as resonance structures or canonical structures) into a resonance hybrid (or hybrid structure) in valence bond theory.
This type of probing assay uses the structure dependent cleavage of RNA; single stranded regions are more flexible and unstable and will degrade over time. [38] The process of in-line probing is often used to determine changes in structure due to ligand binding. Binding of a ligand can result in different cleavage patterns.
(2) The PARENT and CHOOSE operations determine the optimal set of NBOs corresponding to a specific resonance structure. Additionally, CHOOSE is able to eliminate identical resonance structures. (3) A user may then call SELECT to select the structure that best matches to the true molecular structure.
Expressing resonance when drawing Lewis structures may be done either by drawing each of the possible resonance forms and placing double-headed arrows between them or by using dashed lines to represent the partial bonds (although the latter is a good representation of the resonance hybrid which is not, formally speaking, a Lewis structure ...
Nuclear magnetic resonance structure determination generates an ensemble of structures. The structures will converge only if the data is sufficient to dictate a specific fold. In these structures, it is the case for only a part of the structure. From PDB entry 1SSU.
The thick lines denote coincident electron pairs. (b) The traditional valence bond theory structure for the B 2 H 6 molecule. The thin curved lines stretching across the boron-hydrogen-boron moiety indicate that the two bonding electrons are delocalised across these three centres. (c) The resonance structures for the B 2 H 6 molecule.
The methods by which one can determine the structure of a molecule is called structural elucidation.These methods include: concerning only connectivity of the atoms: spectroscopies such as nuclear magnetic resonance (proton and carbon-13 NMR), various methods of mass spectrometry (to give overall molecular mass, as well as fragment masses).Techniques such as absorption spectroscopy and the ...