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In chemistry, molecular orbital theory (MO theory or MOT) is a method for describing the electronic structure of molecules using quantum mechanics. It was proposed early in the 20th century. The MOT explains the paramagnetic nature of O 2, which valence bond theory cannot explain.
A number of applications of FMO to biochemical problems has been published, for instance, to Drug design, quantitative structure-activity relationship as well as the studies of excited states and chemical reactions of biological systems. The adaptive frozen orbital (AFO) treatment of the detached bonds was developed for FMO, making it possible ...
The 1b 1 MO is a lone pair, while the 3a 1, 1b 2 and 2a 1 MO's can be localized to give two O−H bonds and an in-plane lone pair. [30] This MO treatment of water does not have two equivalent rabbit ear lone pairs. [31] Hydrogen sulfide (H 2 S) too has a C 2v symmetry with 8 valence electrons but the bending angle is only 92°.
Compounds that obey the 18-electron rule are typically "exchange inert". Examples include [Co(NH 3) 6]Cl 3, Mo(CO) 6, and [Fe(CN) 6] 4−. In such cases, in general ligand exchange occurs via dissociative substitution mechanisms, wherein the rate of reaction is determined by the rate of dissociation of a ligand. On the other hand, 18-electron ...
The Hückel method or Hückel molecular orbital theory, proposed by Erich Hückel in 1930, is a simple method for calculating molecular orbitals as linear combinations of atomic orbitals. The theory predicts the molecular orbitals for π-electrons in π-delocalized molecules , such as ethylene , benzene , butadiene , and pyridine .
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To use FMO theory, the reaction should be considered as two separate ideas: (1) whether or not the reaction is allowed, and (2) which mechanism the reaction proceeds through. In the case of a [1,5] shift on pentadiene, the HOMO of the sigma bond (i.e., a constructive bond) and the LUMO of butadiene on the remaining 4 carbons is observed.
Missouri saw more than 2,000 overdose deaths between November 2022 and November 2023, according to the most recent data available from the CDC. Kansas recorded about 650 for the same time period.