Dissemin is shutting down on January 1st, 2025

Published in

Springer Verlag, Theoretical Chemistry Accounts: Theory, Computation, and Modeling, 2(134)

DOI: 10.1007/s00214-015-1619-5

9th Congress on Electronic Structure: Principles and Applications (ESPA 2014), p. 15-24

DOI: 10.1007/978-3-662-49221-5_3

Links

Tools

Export citation

Search in Google Scholar

Triplet–singlet gap in structurally flexible organic diradicals

This paper is available in a repository.
This paper is available in a repository.

Full text: Download

Green circle
Preprint: archiving allowed
Green circle
Postprint: archiving allowed
Red circle
Published version: archiving forbidden
Data provided by SHERPA/RoMEO

Abstract

A key factor in the search of high-spin ground state purely organic molecules concerns the effect of the inherent non-rigid structures on the magnetic and optical properties. This structural feature has not been properly addressed in previous theoretical works. Here, based on the experimentally characterized high-spin ground state of dendritic and star-branched polyradicals, we study four alternant hydrocarbon biradicals that intend to model these effects and, at the same time, provide a first step toward understanding more extended experimental structures. A series of density functional theory (DFT) and of wave function-based methods have been used to explore the richness of structural minima in the corresponding potential energy surfaces and to discuss its effect on the triplet-singlet gap of the proposed model systems. For a given model, the DFT-based B3LYP, M06-2X and MN-12SX methods provide a consistent description. Likewise, a multiconfigurational quasi-degenerate perturbation theory approach with the minimal π space as CASSCF reference is found to provide unbiased results. Despite the conformational richness found for these systems, they all can be described by a reduced set of values referred to only two structural parameters, being those the dihedral angles between the phenyl rings. For a given model, there is no significant change in the triplet-singlet gap depending on the chosen local minima.