Please use this identifier to cite or link to this item: http://hdl.handle.net/2445/154509
Title: Formation of long, multicenter pi-[TCNE](2)(2-) dimers in solution: solvation and stability assessed through molecular dynamics simulations
Author: Capdevila-Cortada, Marcal
Ribas Ariño, Jordi
Chaumont, Alain
Wipff, Georges
Novoa Vide, Juan J.
Keywords: Dinàmica molecular
Simulació per ordinador
Molecular dynamics
Computer simulation
Issue Date: 1-Nov-2016
Publisher: Wiley-VCH
Abstract: Purely organic radical ions dimerize in solution at low temperature, forming long, multicenter bonds, despite the metastability of the isolated dimers. Here, we present the first computational study of these pi-dimers in solution, with explicit consideration of solvent molecules and finite temperature effects. By means of force-field and ab initio molecular dynamics and free energy simulations, the structure and stability of pi-[TCNE](2)(2-) (TCNE = tetracyanoethylene) dimers in dichloromethane have been evaluated. Although the dimers dissociate at room temperature, they are stable at 175 K and their structure is similar to the one in the solid state, with a cofacial arrangement of the radicals at an inter-planar separation of approximately 3.0 angstrom. The pi-[TCNE](2)(2-) dimers form dissociated ion pairs with the NBu4+ counterions, and their first solvation shell comprises approximately 20 CH2Cl2 molecules. Among them, the eight molecules distributed along the equatorial plane of the dimer play a key role in stabilizing the dimer through bridging C-H center dot center dot center dot N contacts. The calculated free energy of dimerization of TCNE center dot- in solution at 175 K is -5.5 kcal mol(-1). These results provide the first quantitative model describing the pairing of radical ions in solution, and demonstrate the key role of solvation forces on the dimerization process.
Note: Versió postprint del document publicat a: https://doi.org/10.1002/chem.201603537
It is part of: Chemistry-A European Journal, 2016, vol. 22, num. 47, p. 17035-17044
URI: http://hdl.handle.net/2445/154509
Related resource: https://doi.org/10.1002/chem.201603537
ISSN: 0947-6539
Appears in Collections:Articles publicats en revistes (Ciència dels Materials i Química Física)

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