title: Quantitative prediction and interpretation of spin energy gaps in polyradicals: the virtual magnetic balance.
abstract: Open-shell organic molecules possessing more than two unpaired electrons and sufficient stability even at room temperature are very unusual, but few were recently synthesized that promise a number of fascinating applications. Unfortunately, reliable structural information is not available and only lower limits can be estimated for energy splittings between the different spin states. On these grounds, we introduce here an effective 'virtual magnetic balance', a robust and user-friendly tool purposely tailored for polyradicals and devised to be used in parallel with experimental studies. The main objective of this tool is to provide reliable structures and quantitative splittings of spin states of large, complex molecules. We achieved this objective with reasonable computation times and in a theoretical framework that allows disentanglement of different stereo-electronic effects contributing to the overall experimental result. A recently synthesized tetraradical with remarkable chemical stability was used as a case study.
authors.affiliation: Scuola Normale Superiore, piazza dei Cavalieri, I-56126 Pisa, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Barone
authors.affiliation: Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 13, I-56124, Pisa, Italy. ivo.cacelli@unipi.it and Istituto di Chimica dei Composti OrganoMetallici (ICCOM-CNR), Area della Ricerca, via G. Moruzzi 1, I-56124 Pisa, Italy.
authors.forename: Ivo
authors.identifier: http://orcid.org/0000-0001-9941-1800
authors.initials: I
authors.lastname: Cacelli
authors.affiliation: Istituto di Chimica dei Composti OrganoMetallici (ICCOM-CNR), Area della Ricerca, via G. Moruzzi 1, I-56124 Pisa, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Ferretti
authors.affiliation: Istituto di Chimica dei Composti OrganoMetallici (ICCOM-CNR), Area della Ricerca, via G. Moruzzi 1, I-56124 Pisa, Italy.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Prampolini