The nature of bonding in pericyclic and pseudopericyclic transition states: Thermal chelotropic decarbonylations

Abstract

An ab initio potential energy surface and vibrational states of MgH 2 (1 1 A ′ ) Two functions of the density matrix and their relation to the chemical bondThe electron localization function ͑ELF͒, a local measure of the Pauli repulsion, is shown like a useful descriptor of bonding at pericyclic and pseudopericyclic transition states. The main differences between these two relevant topologies have been investigated in detail through the examination of well-characterized typical allowed-symmetry thermal decarbonylations. It is shown that results based on the electron fluctuation between the ELF basin populations at the reaction center, provides a consistent description of bonding which complements the traditional Woodward-Hoffmann symmetry-orbital based analysis.

Borazine: to be or not to be aromatic

“…The higher the separation value, the higher is the expected degree of localization of electron pairing between these domains [47][48][49]. Such a bifurcation analysis is a useful tool to rationalize the nature of chemical bonding of aromatic substitution and reactive sites [51,52], pericyclic reactions [53][54][55], radical systems (e.g., through the analysis of the a-b spin components) [56], and the definition of an aromaticity scale for organic molecules and clusters via the analysis of r and p contributions to density [26,57].…”

Fluorine effect on pericyclic and pseudopericyclic processes: Evidences and ab initio theory

“…This method has been chosen as it has been found reliable in earlier reports 22,34 and especially for thermolysis reactions. 34 Stationary points have been characterized by computing vibrational frequencies; reactants, products have all real frequencies and TSs have one imaginary frequency.…”

“…Lopez and de Lera et al 20 showed that pseudopericyclic reactions do not show a maximum in ellipticity of the forming bond along the reaction coordinate. Recently ELF, BCP [21][22][23][24][25][26] analyses have also been used to differentiate pericyclic reactions from pseudopericyclic reactions.…”

A Density Functional Theory Study on the Electrocyclization of 1,2,4,6‐Heptatetraene Analogues: Converting a Pericyclic to a Pseudopericyclic Reaction

“…Hence, pseudopericyclic reactions cannot be orbital symmetry forbidden. Recently, Birney et al [2][3][4][5][6][7][8][9][10] and others [11][12][13][14][15][16][17][18][19][20] showed that a number of organic syntheses involve this type of process. Although Lemals definition is seemingly quite clear, there is some ambiguity as the orbital description is not unique; thus, any unit transformation of canonical molecular orbitals can be used to reproduce molecular properties.…”