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Dynamic Molecular Graphs: “Hopping” Structures
Author(s) -
CortésGuzmán Fernando,
RochaRinza Tomas,
GuevaraVela José Manuel,
Cuevas Gabriel,
Gómez Rosa María
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201303287
Subject(s) - molecular dynamics , chemical physics , molecule , atom (system on chip) , chemistry , density functional theory , molecular orbital , electron localization function , molecular graph , trimethylenemethane , fragment molecular orbital , computational chemistry , topology (electrical circuits) , crystallography , electron , physics , graph , quantum mechanics , cycloaddition , computer science , mathematics , combinatorics , biochemistry , catalysis , embedded system
This work aims to contribute to the discussion about the suitability of bond paths and bond‐critical points as indicators of chemical bonding defined within the theoretical framework of the quantum theory of atoms in molecules. For this purpose, we consider the temporal evolution of the molecular structure of [Fe{C(CH 2 ) 3 }(CO) 3 ] throughout Born–Oppenheimer molecular dynamics (BOMD), which illustrates the changing behaviour of the molecular graph (MG) of an electronic system. Several MGs with significant lifespans are observed across the BOMD simulations. The bond paths between the trimethylenemethane and the metallic core are uninterruptedly formed and broken. This situation is reminiscent of a “hopping” ligand over the iron atom. The molecular graph wherein the bonding between trimethylenemethane and the iron atom takes place only by means of the tertiary carbon atom has the longest lifespan of all the considered structures, which is consistent with the MG found by X‐ray diffraction experiments and quantum chemical calculations. In contrast, the η 4 complex predicted by molecular‐orbital theory has an extremely brief lifetime. The lifespan of different molecular structures is related to bond descriptors on the basis of the topology of the electron density such as the ellipticities at the FeCH 2 bond‐critical points and electron delocalisation indices. This work also proposes the concept of a dynamic molecular graph composed of the different structures found throughout the BOMD trajectories in analogy to a resonance hybrid of Lewis structures. It is our hope that the notion of dynamic molecular graphs will prove useful in the discussion of electronic systems, in particular for those in which analysis on the basis of static structures leads to controversial conclusions.