Chemistry: A Panoply of Arrows

Álvarez, Santiago

doi:10.1002/anie.201101767

Cited by 31 publications

(14 citation statements)

References 46 publications

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“…The discussion of the reactivity of a chemical system is generally based on reaction schemes in which arrows highlight the movement of electrons accompanying the rearrangements of atoms. 44 As we have shown in the previous section, the centroids of the localised orbitals provide a representation of bonds and lone pairs, and it would be tempting to associate the displacement of the centroids to the arrows drawn in reaction schemes. Indeed, this approach had been pursued in the past to describe organic reactions, 45,46 and we applied it here to a series of organometallic complexes capable of C-H bond activation.…”

Section: Reaction Mechanisms: Arrowsmentioning

confidence: 99%

The use of localised orbitals for the bonding and mechanistic analysis of organometallic compounds

Vidossich

Lledós

2014

Dalton Trans.

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Through a series of examples we show how, upon orbital localisation, the outcome of an electronic structure calculation reveals features, such as bonding and oxidation states, which are controversial to grasp by alternative methods. The approach can also be applied to the analysis of reaction mechanisms. Because of the insight it provides in a limited execution time, we believe that this approach, known since the early developments of computational quantum chemistry, could find wider applications in the organometallic community than it actually has and facilitate communication between computational and experimental chemists.

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Section: Reaction Mechanisms: Arrowsmentioning

confidence: 99%

The use of localised orbitals for the bonding and mechanistic analysis of organometallic compounds

Vidossich

Lledós

2014

Dalton Trans.

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“…Chemists saw (and still see) mostly with VB eyes, even drawing benzene with Kekulé formula which detracts from MO eyes. Using curly arrows to depict reaction mechanisms is also essentially a VB approach [179–183] . Chemists needed to understand molecular orbital theory, especially frontier molecular orbital theory, to solve the pericyclic no‐mechanism problem or to understand the solutions proposed by others.…”

Section: Orbitals With and Without Phases (And Nodes)mentioning

confidence: 99%

History of the Woodward‐Hoffmann Rules. The No‐Mechanism Puzzle**

Seeman

2022

The Chemical Record

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This is Paper 2 in the 27‐paper series on the history of the development of the Woodward‐Hoffmann rules. Paper 2 takes the reader back to the 1950s and early 1960s, before the publication of the first Woodward‐Hoffmann paper in January 1965. The scope of the pericyclic no‐mechanism problem is described along with many of the key “hints” or “clues” to orbital symmetry control that were available in the literature prior to 1965. A chronology of reactions with alternating stereospecificities is provided. A second chronology of alternating theoretical hints is provided, e. g., 4n+2 versus 4n. Another chronology is provided, that of the development of frontier molecular orbital theory, with and without phases and nodes. A tabulation is provided of 36 instances in which the MOs of 1,3‐butadiene were reported in the literature. A knowledge of the MOs of 1,3‐butadiene, plus a knowledge of some of the alternating stereospecific reactions, could have led many chemists to the solution of the pericyclic no‐mechanism problem before Woodward and Hoffmann.

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“…Alvarez [29] presented an overview on the historical use of arrows in chemistry, providing the variety of meanings that a simple symbol such as an arrow may have: the alchemical symbols representing elements or compounds; in chemical equations to show the reversibility of a given chemical process; double-headed arrow to represent resonance structures or even tautomerism associated with the interconversion of two isomers through a simultaneous shift of a double bond and a proton; in orbital energy diagrams; in the Jablonski diagrams indicating radiative (straightarrows) and nonradiative (wavy arrows) transitions; in the stimulated emission of radiation that takes place in lasers; and up-and down-pointing arrows to depict the positive and negative spin of an electron.…”

Section: Reaction Mechanismmentioning

confidence: 99%

Unraveling reaction mechanisms by means of Quantum Chemical Topology Analysis

Andrés

González-Navarrete

Safont

2014

Int J of Quantum Chemistry

100

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A chemical reaction can be understood in terms of geometrical changes of the molecular structures and reordering of the electronic densities involved in the process; therefore, identifying structural and electronic density changes taking place along the reaction coordinate renders valuable information on reaction mechanism. Understanding the atomic rearrangements that occur during chemical reactions is of great importance, and this perspective aims to highlight the major developments in quantum chemical topology analysis, based on the combination of electron localization function and catastrophe theory as useful tools in elucidating the bonding and reactivity patterns of molecules. It reveals all the expected, but still ambiguous, elements of electronic structure extensively used by chemists. The chemical bonds determine chemical reactivity, and this technique offers the possibility of their visualization, allowing chemists to understand how atoms bond, how and where bonds are broken/ formed along a given reaction pathway at a most fundamental level, and so, better following and understanding the changes in the bond pattern. Their results clearly herald a new era, in which the atomic imaging of chemical bonds will constitute a new method for examining chemical structures and reaction mechanisms. The important feature of this procedure is that in practice the scope of its values is systemindependent. In addition, from a practical point of view, it is cheap to calculate and implement because wave functions are the required input, which are easily available from standard calculations. To capture these results two reaction mechanisms: isomerization of C(BH) 2 carbene and the thermal cycloheptatriene-norcaradiene isomerizations have been selected, indicating both the generality and utility of this type of analysis.

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Chemistry: A Panoply of Arrows

Cited by 31 publications

References 46 publications

The use of localised orbitals for the bonding and mechanistic analysis of organometallic compounds

The use of localised orbitals for the bonding and mechanistic analysis of organometallic compounds

History of the Woodward‐Hoffmann Rules. The No‐Mechanism Puzzle**

Unraveling reaction mechanisms by means of Quantum Chemical Topology Analysis

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